Android Basic Tutorial

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ANDROID
Android is open source device independent Mobile operating system
Developed by Andy Rubbin in the Year 2005, Present Android Manager at Google Picheai
Google Introduced OHA (Open Handset Alliances) combination of Different Platform companies
Android Categories 4 and 17 Versions up to 2012
1X – Only for Mobile Phones
2X– Only for Mobile Phones
3X– Only for Tablet PCs
4X – For both Mobile and Tablet PCs
Software Requirements for Android
Android SDK, Core Java, Android XML, Eclipse IDE
Android Architecture
Android Operating System
Android Application
Android Application Framework (Android API Google API and Java API)
Native Libraries Execution Area (DVM)
Linux Kernel
Application Development Components
Resources (Images, Audio/Video files, Text files …etc.): Before design any android application it is highly
recommended to add the resources like audio/video files, text files…Etc.
Layout Files: Layout are the GUI screens in Android Applications, which will gives Provisioning to the end
user either to provide input values or to check the output.
Activity Classes: java code to perform the operation (Business Logic)
Manifest File: This is the Starting Executable file by the DVM, in this all the activity files should registered
and it decides the First Executable file.
Android Project Directory Structure
src: Contains the Java packages the developer writes or imports for the application. Each package can
have multiple .java files representing different classes.
res/ layout: Contains XML files that contains the layout of each screen.
res/values: Contains XML Files used as reference by other files (strings, dimensions, colors…etc.)
res/raw: Contains Audio/Video files
res/menu: Contain Menu items
res/drawable-hdpi/mdpi…: Contains density wise pixel images which are used for application.
assets: Contains Additional non media files the application uses
gen: Contains auto generated code, including the generated class R.java.
Android Mainfest.xml: Specifies the project to the Android OS.

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Execution Flow of Android Application Tools Files
Android assets
Packaging tools
(AAPT) will
compress the
Manifest,
Resource
Resources,
Layout files into
common
DX Tool will convert
the all .class files in to
.dex files (Dalvik
Executable Files)
Java Compiler
Converts .java Files
into .class files
Used to
Compress the
AAPT package
and .dex files
.apk compressed Android
application file (Executable file in
Dalvik Virtual Machine)
Manifest
File ………………………etc.Audio/Video Images Text Files
Layout
Files
Act1.
java
Act2.
java
Act3.
java
R.java
JVM
Act1.
class
Act2.
class
Act3.
class
R.Class
DX
Tool
.dex
File
s
APK
Builder
.apk
Files
Android OS
and DVM
(Emulator of
Mobile)
API
Android
JAVA
Google
AAP
Tool
Auto Generated .Java
file for resource
registration

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SYNTAXES
1. Activity Class:
Class <class name> extends Activity
{
@Override
public void onCreate(Bundle saveInstantState)
{
Super.onCreate(saveInstantState);
setContentView(R.Layout.XMLFileName);
:::::::
::::::: //Business Logic
:::::::
:::::::
:::::::
::::::: //Business Logic perform some operation
:::::::
:::::::
}
* saveInstantState or any objref
2. Programmatically Registrations
EditText e1 =(EditText)findViewById(R.id.EditText1);
String s1=e1.getTest().toString();
Button b1 = (Button)findViewById(R.id.Button1);
b1.onClickListener(this);
ImageView v1=(ImageView)findViewById(R.id.image);
v1.setImageResource(r.drawable.myimage);
3. Normal Switching
Intent objref=new Intent(SourceActivity context, DestinationActivityclassname.class);
startActivity(objref);
Example
Intent i=new Intent(this,Act2.class);
startActivity(i);
4. Switching with data
Act1.java
{
:::::::
}

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public void onClick(View v)
{
Intent i= new Intent(this, Act2.class);
i.putExtra(“key1”,vol1);
:::::::
:::::::
startActivity(i);
}
Act2.java
{
:::::::
:::::::
:::::::
Bundle b=get Intent().getExtras();
String s1=b.getString(“key1”);
:::::::
:::::::
::::::: //Business Logic operation
:::::::
:::::::
}
*putExtra(): add input values (“key”,value)
*getIntent(): source objref(i)
*getExtras():getting source data
*getString()-String format
*getInt():Integer format
*getFloat(): Float format …etc.
5. Switching with Result Data
Act1.java
Public static final int REQ_CODE =4;
{
:::::::
}
public void onClick(View v){
Intent i= new Intent(this, Act2.class);

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:::::::
startActivityforResult(i);
}
public void onActivityResult(Req code, Res Code, Intent obj)
{
If (REQ_CODE=Req code){
Bundle b1=obj.getExtras();
String s=b1.getString(“Keyres”);
:::::::
} }
Act2.java
Public static final int RESULT_OK =2;
{
:::::::
Bundle b=get Intent().getExtras();
:::::::
:::::::
}
public void finish(){
Intent obj =new Intent(this,Act1.class);
obj.putExtra(“keyres”,Volue);
::::::
setResult(I,RESULT_OK);
super.finish();
}
6 .Implicit Switching
a) Contact Intent
Intent i=new Intent();
i.setAction(android:Content.Intent.ACTION_VIEW);
i.setData(ContactContract.Contacts.CONTENT_URI);
startActivity(i);
(or)
Intent i=new Intent(Intent.ACTION_VIEW,ContactsContract.Contacts.CONTENT_URI);
startActivity(i);
Manifest permission: READ_CONTACTS

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b) Browser Intent
Intent i=new Intent();
i.setAction(android:Content.Intent.ACTION_VIEW);
i.setData(Uri.parse(“httpwww.yahoo.com”));
startActivity(i);
(or)
Intent i=new Intent(Intent.ACTION_VIEW,Uri.parse(“httpwww.google.com”));
startActivity(i);
Manifest permission: INTERNET
c) Search Intent
Intent i=new Intent(Intent.ACTION_WEB_SEARCH);
i.putExtra(SearchManger.QUERY,"androidbboks”);
startActivity(i);
d) Map Intent
Intent i= new Intent(Intent.ACTION_VIEW,Uri.parse(“geo:0,0?q=Hyderabad”);
startActivity(i);
Manifest permission: INTERNET and ACCESS_FINE_LOCATION
e) Call Intent
Intent i= new Intent(Intent.ACTION_CALL,Uri.parse(“tel:9876543210”));
startActivity(i);
Manifest permission: CALL_PHONE
7. Menu Design
a) Options Menu
I) Options Menu (with text items)
{
:::::::
}
public boolean onCreateOptionsMenu(Menu m)
{
m.add(group Id, item Id, order, “Item Name”);
:::::::
return(true); }
@Override
public boolean onOptionsItemSelected(MenuItem mi)
{
switch(mi.getId()){

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case : {:::::}
case : {:::::}
return(true)}
II) Options Menu (with Images)
*create menu.xml files in (app/res/values/menu/menu.xml)
@Override Methods
1) onCreateOptionsMenu(Menu m)
2) onOptionsItemSelected(MenuItem mi)
{
:::::::
}
public boolean onCreateOptionsMenu(Menu m)
{
MenuInflater mf=this.getMenuInflater();
mf.Inflate(R.menu.menu,m);
return(true);
}
public boolean onOptionsItemSelected(MenuItem mi)
{
switch(mi.getId()){
case : {:::::}
return(true)
}
b) Context Menu
Create String_array.xml in resource folder
@Override
1) onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo Menuinfo)
2) onContextItemSelcted(MenuItem mi)
public class ContextMenu extends Activity
{
ListView lv; String countries[];
public void onCreate(Bundle b)
{
super.onCreate(b);
setContentView(R.Layout.main);
lv=this.getListView();
countries=getResources().getStringArray(R.arrya.countries);
ArrayAdapter<String> adp=new ArrayAdapter<String>(this,android.R.layout.Smiple_List_Item_1,
countries);
lv.setAdapter(adp);
registerForContextMenu(lv);

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}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo Menuinfo)
AdapterContextMenuInfo acm=(AdapterContextMenuInfo)Menuinfo;
menu.setHeaderTiltle(Countries(acm.position));
menu.add(menu.NONE,1,meu.NONE,”Edit”);
menu.add(menu.NONE,1,meu.NONE,”Map”);
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Super.onCreateContextMenu(menu,v,menuinfo);
}
@Override
Public void Boolean onCreateItemSelected(MenuItem mi)
{
switch(mi.getId()){
case: {:::::}
case: {:::::}
}
Return super.onContextItemSelected(mi);
}
}
8. Dialogs
a) Toast Message
b) Alert Dialog
c) Input Dialog
d) Date Picker Dialog
e) Time Picket Dialog
f) Progress Dialog
a) Toast Message
Toast objref=Toast.makeText(context,”Messgae”,duration);
objref.show();
*context: current class object (this)
*duration: Toast.LENGTH_LONG, Toast.LENGTH_SHORT.
b) Alert Dialog
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setIcon(R.drawable.image);
builder.setTitle("Title......");
builder.setMessage("Message......");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Title…….
.
Message
O

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:::::::
::::::: //Defining action for OK Button
:::::::
}
});
builder.show();
}
}
c) Input Dialog
AlertDialog.Builder id = new AlertDialog.Builder(this);
id.setTitle("Title......");
final EditText et=new EditText(this);
id.setView(et);
dsetPositiveButton("OK", new DialogInterface.OnClickListener() {
:::::::
:::::::
}
});
id.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
::::::
:::::::
}
});
Id.show();
}
d) Time Picker Dialog
TimePickerDilog tp=new TimePickerDilog(this, null, hours,Minuts,true);
tp.show();
e) Date Picker Dialog
DatePickerDilog dp=new DatePickerDilog(this, null, year,month,date);
dp.show();
f) Progress Dialog
final ProgressDialog pd=new ProgressDialog(this);
pd.setProgress(10);
pd.setTitle("Progress Dialog");
pd.setMessage("Progress is going on..");
pd.show();
::::::
::::::: //Logic
}
Title…….
.
Text Box
Ca
nc
O
K

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new Thread(){
public void run(){
try{
Thread.sleep(2000);
}catch(Exception e){
}
pd.dismiss();
}
}.start();
}
9. Activity Life Cycle Methods
public void onCreate(){super.onCreate();::::::::::::::::::::::::::::}
public void onStart(){super.onStart();::::::::::::::::::::::::::::}
public void onResume(){super.onResume();::::::::::::::::::::::::::::}
public void onRestart(){super.onRestart();::::::::::::::::::::::::::::}
public void onPause(){super.onPause();::::::::::::::::::::::::::::}
public void onStop(){super.onStop();::::::::::::::::::::::::::::}
public void onDestroy(){super.onDestroy();::::::::::::::::::::::::::::}
10. Multimedia
Manifest permission: RECORD_AUDIO //for recording audio
Manifest permission: WRITE_EXTERNA_STORAGE////for recording audio
<uses-feature android:name=”android.Hardware.Camera”/>
a) Working with Images
b) Working with Audio Files
c) Working with Video Files
d) Working with Animations
a) Working with Images
i) Resources Image
ImageView iv=(ImageView) findViewById(R.id.iv1);
iv.setImageResources(R.drawable.image1);
ii) Capture Images
Intent camIntent=new Intent(android.provider.Mediastore.ACTION_IMAGE_CAPTURE);
startActivityForResult(camIntent, req id);
Public void onActivityForResult(req id, res id, Intent data){
Bitmap thumbnail=(Bitmap)data.getExtras().get(“data”);
ImageView iv=(ImageView) findViewById(R.id.iv1);
iv.setImageBitmap(thumbnail);

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b) Working with Audio Files
i) Playing Resource Songs
MediaPlayer mp=new MediaPlayer.create(this,R.raw.song1);
mp.start();
public void onDestroy()
{
mp.release();
}}
iii) Playing Local Songs
Uri myuri=”Myfiles/downloads/song3”
MediaPlayer mp=new MediaPlayer();
Mp.setAudioStreamType(AudioManger,STREAM_MUSIC);
Mp.setDataSource(this,myuri);
Mp.prepare();
Mp.start();
iv) Playing Remote Songs
Uri myuri=”http://www.songs.com”
MediaPlayer mp=new MediaPlayer();
Mp.setAudioStreamType(AudioManger,STREAM_MUSIC);
Mp.setDataSource(this,myuri);
Mp.prepare();
Mp.start();
v) Recording Voice (Capture Audio)
MediaRecorder mr=new MediaRecorder();
mr.setAudioSource(mr.AudioSource.MIC);
mr.setOutputFormat(mr.OutputFormat.THREE_GPP);
mr.setAudioEncoder(mr.AudioEncoder.AMR_NB);
mr.setOutputFile(“sdcard/abc.3gp);
mr.prepare();
mr.start();
mr.stop();
mr.release();

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c) Working with Video Files
i) Playing Video
VideoView vv=(VideoView)findViewById(r.id.SurfaceView);
vv.setVideoURI(Uri.parse(“android:resource://”+getPackagename()+”/”+R.raw.filename);
vv.setMediaControler(new MediaControler(this));
vv.requestFocus();
ii) Capturing Video
Intent videoIntent=new Intent(android.provider.Mediastore.ACTION_VIDEO_CAPTURE);
startActivityForResult(videoIntent, req id);
vv.setVideoURI(uri);
vv.start();
VideoFile uri=data.getData();
d) Working with Animations
i) AlphaAnimation – Controls transparency changes
ii) RotateAnimation – Controls rotations
iii) ScaleAnimation – Controls growing or shrinking
iv) TranslateAnimation – Controls position changes
The four animation classes can be used for transitions between activities, layouts, views and so on. All
these can be defined in the layout XML file as <alpha>, <rotate>, <scale>, and <translate>. They all to be
contained within an AnimationSet <set>:
res/anim/animated.xml
<alpha> attributes:
android:fromAlpha=”0.0” android:toAlpha=”0” android:duration=”3000”
<rotate> attributes:
android:fromDegrees=”0”, android:toDegrees=”180”
android:pivotX=”50%”, android:pivotY=”50%”
android:duration=”3000”
<scale> attributes:
android:fromXScale=”0.0”, android:toXScale=”1.4”
android:fromYScale=”0.0”,, android:toYScale=”1.4”
android:pivotX=”50%”, android:pivotY=”50%”
<translate> attributes:
android:fromXDelta=”100%p”, android:toXDelta=”0”
android:fromYDelta=”100%p”,, android:toYDelta=”0”
android:duration=”3000”

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final ImageView im=(ImageView)findViewById(r.id.myimage);
final Animation an=AnimationUtils.loadAnimation(this,R.anim.Animated);
im.setVisibility(view.VISIBLE);
im.setVisibility(view.INVISIBLE);
im.startAnimation(an)
11. Services
Manifest : <Service android:name=”.ServiceClassName”/> //for user defined services
Services Life Cycle
Service is executing background of the android application
1) Predefined Services
2) User defined Services
Predefined Services:
ServiceClassName objref=(ServiceClassName)this.getSystemService(Service type);
(or)
ServiceClassName objref=(ServiceClassName)this.getSystemService(context.Service type);
a) Vibrator
Vibrator vb=(Vibrator)getSystemService(VIBRATOR_SERVICE);
vb.vibrate(duration);
Service is
started by
onCreate()
onStart()
Service is
running
The service is
stopped (no
onDestroy()
Service is
shut down
Service is
started by
onCreate()
onBind()
Clint interacts with
the service
onUnbind()
onDestroy()
Service is
shut down
onRebind()

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b) AlarmManager
AlarmManger am=(AlarmManager)getSystemService(ALARAM_SERVICE);
c) Location Manager
GPS Applications
d) Notification Manager
Notification window to display Notification messages like Missed calls, alarm information, reminders etc.
NotificationManager nm=(NotificationMangaer)getSystemService(NOTIFICATION_SERVICE);
To display notification on Title bar android API supports Notification()
Notification n=new Notification(Icon, “Messgae”, Duration);
Ex: n=new Notification(R.drawable.icon, “Reminder: Messages”, system.cuurentTimeMillis()+6000);
Syntax to Display Notification Message in Notification Window
n.setLatestEventInfo(this, Title, Message, Pending Intent);
e) Wi-Fi Manager
Wi-Fi Applications
f) Bluetooth Adapter
g) SMS Manager……etc.
SMSManager sms=(SMSManager)getSystemService(SMS_SERVICE);
Sm.setTextMessage(“destination”, “msgcenter”, ”Message”, PendingIntent SentIntent, PendingIntent
DeliverIntent);
*String destination=”9876543210”
*String Message=”Hi world”
*PendingIntent: Intent class used to achieve the switching between two activities after waiting some
time.
Manifest permission: SEND_SMS
User Defined Services
public void ServiceClassName extends Service
{
public IBinder onBind(Intent is){
return(null)
}
public void onCreate()
{
::::::::
}
public void onStart(Intent I, int StartId)
{
:::::::::
}
public void onSestroy()
{
::::::::::
}}

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Call service into Activity class
Intent is=new Intent(this, ServiceClassName.class);
startService(is);
stopService(is);
12. Text to Speech Conversion
TextToSpeech tts=new TextToSpeech(context,TextToSpeech.onInitListener objref);
* TextToSpeech.onInitListener objref = Default TTS Engine supports by the android device (this)
Methods of TextToSpeech Class
a) getDefaultEngine()
Used to get the package name of the default speech synthesis engine, returns String value
b) getEngines()
This will gives the all the list of Installed TTS engines returns List (interface)
c) getLanguage()
Get the Language currently associated with the TTS engine
d) isSpeaking()
If returns TRUE TTS Engine was busy with speaking otherwise returns FALSE
e) setLanguage(Local loc)
It will set the TTS Language
f) setPitch()
To set speech pitch normal (=1)/low (>1.0)/high (<1.0)
g) setSeechRate(float SpeechRate)
To set speech rate normal (=1)/slower (>1.0)/faster (<1.0)
h) stop()
Used to stop the current TTS Message temporarily
i) shutdown()
Used to stop the current TTS Message permanently
j) onInit(Int Status)
@Overridden Method
public void onInit(int Status){
::::::::::
::::::::::
}
*If Status=0 Activation of TTS Engine was done SUCCESSFULLY
k) speak(String text, int QUEUMODE, HashMap<String , String>prams)
* QUEUMODE: QUEUE_ADD: This will add the new entry at the end of the play back.
QUEUE_FLUSH: This will add the new entry at the end of the play back.
public class TextToSpeechActivity extends Activity implements TextToSpeech.onInitListener
{
TextToSpeech tts;
super.onCreate(b);
setContentView(R.layout.xmlfile);
:::::::::::
:::::::::::
tts=new TextToSpeech(this,this);

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}
public void onDestroy()
{
If(tts!=null){
Tts.stop();
Tts.shutdown();
}
Super.onDestroy();
}
Public void onInit(int Status);
{
If(Status=TextToSpeech.SUCCESS){
Tts.setLanguage(Locale.us);
Tts.setPitch(1.0);
Tts.setSpeeakRate(1.0);
//speakOut() /*user defined method.
}
public void speeakOut()
{
String text=text // whatever you want to speak out
Tts.Speak(text,TextToSpeech.QUEUE_FLUSH,null);
}
}
13. Data Storage Methods (Internal and External Storage)
1) Phone Memory (Internal Storage).
2) SD Card or External Storage.
3) SQLite Database.
We can store any type of data in the form of files either in Internal (or) External Memory.
Android was introduced Local Database to store the data permanently and securely, this is the
part of Internal Memory (SQLite Data Base).
Android API Supports predefined classes to work with Internal and External Memory, SQLite
Database that means we can able to design
Our own Android Application to store the data in any of the above locations.
Internal and External Memory always supports storing of data in the form of files like Text files,
Image Files, Audio and Video Files...etc.,
SQLite Database is used to store the data in the form of TABLES.
1) Working With Phone Memory (or) Internal Memory
It is a default memory comes along with every real device. It supports very less memory space
compared to SD Card.
In Internal Memory mainly we can perform two types of operations
1) Storing the data in the form of files.
2) Retrieving data in the form of files.
Predefined Methods for Internal Memory

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a) getFilesDir()
It can be used to get the root path of the system directly where the internal files are saving by default.
b) getDir()
This method can be used to get the current working directory path in the internal storage?
c) deleteFile()
Used to delete files, which is available in the internal memory.
Storing the data in the form of files
d) OpenFileOutput()
It is a predefined method of Activity class used to open the given file from the internal memory and set
writing mode. If the given file is not available which will create a new file in internal memory with the
same file, this method returns FileOutputStream class Object
Syntax:
FileOutputStream objref=OpenFileOutput (Path of the file, Mode of Access);
*path of the file = which represents location of the file.
*Mode of Access = which represent Accessibility of file.
Accessibility can be
(a) MODE_PRIVATE (Only current activity allows working with the file).
(b) MODE_PUBLIC (Any activity of same application allows working with the file).
Example:
FileOutputStream fos=OpenFileOutput (getFilesDir () +”/abc.txt”, MODE_PRIVATE);
Retrieving the data in the form of files
e) OpenFileInput()
It is a predefined method of Activity class used to open the given file from the internal memory and in
read mode this method returns FileInputStream class Object.
Syntax:
FileInputStream objref=OpenFileInput (Path of the file);
Example:
FileInputStream fis=OpenFileInput (getFilesDir () +”/abc.txt”);
Working with Text Files
In Internal Memory any text file not only can store and retrieve but also any data can be writing
or reading operations can be done.
Write Data in to file:Data can be written into any file by using OutputStream Classes (DataOutputStream,
OutputStreamWriter, ByteArrayOutputStream, BufferedOutputStream, and ObjectOutputStream).
Syntax:
String s=”Hello Friends”;
FileOutputStream fos=OpenFileOutput (getFilesDir () +”/sample.txt”, MODE_PRIVATE);
DataOutputStream dos=DataOutputStream(fos);
dos.writeBytes(s);
(or)
OutputStreamWriter sw=new OutputStreamWriter (fos);
sw.write(s);
fos.close();

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Storing the files in our own directories:
File f=new File (getFilesDir () +”/Sathya/Mydata/../..”);
f.mkDir(); // Create new directory in default root directory.
FileOutputStream fos=OpenFileOutput (getFilesDir () +” Sathya/Mydata /sample.txt”,
MODE_PRIVATE);
OutputStreamWriter sw=new OutputStreamWriter (fos);
sw.write(..);
fos.close();
Reading Data from the text file:
Data can be written into any file by using InputStream Classes (DataInputStream, ByteArrayInputStream,
BufferedInputStream, and ObjectInputStream).
Syntax:
FileInputStream fis=OpenFileInput (getFilesDir () +”/sample.txt”);
DataInputStream dis=DataInputStream(fis);
String s=dis.readLine();
(or)
InputStreamReader sr=new InputStreamReader (fis);
Sr.readLine();
Retrieving date from our own directories:
Syntax:
FileInputStream fisd=OpenFileInput (getFilesDir () +”Sathya/Mydata/sample.txt”);
DataInputStream dis=new DataInputStream (fisd);
String s=dis.readLine();
2) Working with external memory or SD Card
External memory is optional and expandable memory, which can be used to store more data in
file format compared to internal memory.
Android API supports Environment Class to work with SD Card.
Methods for External Memory
a) getExternalStorageState()
Used to get the state of the external storage device, this method returns the following states in
the form of string format.
i) MEDIA_MOUNTED: If Media (SD Card) is present and Mounted (activation) with read and write
access.
ii) MEDIA_MOUNTED_READ_ONLY: Which represents media is present with read only access.
iii) MEDIA_UNMOUNTED: Which represents media is present but no accessibility id given for reading
(or) writing.
iv) MEDIA_BAD_REMOVAL: It will be return if the media was removed before it was un mounted.
v) MEDIA_CHECKING: It will be return if the media is present and being disk checked state.
vi) MEDIA_REMOVED: This will be return if the media is not present.

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b) getExternalStorageDirectory()
Used to get the android external storage directory
c) getExternalStoragePublicDirectory(String type)
Used to get top level public external storage directory files of particular type, Ex: Downloads, Ringtones,
Videos…etc.
i) DIRECTORY_DOWNLODS
ii) DIRECTORY_MOVIES
iii) DIRECTORY_MUSIC
iv) DIRECTORY_PICTURES
Example:
Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES)//This will return
path of the pictures gallery in android device.
d) getRootDirectory()
It returns root directory of Android device (Myfiles/android…).
e) isExternalStorageRemovable()
Returns “TRUE” if the SD Card is removable otherwise returns “FALSE”.
Working with external memory Syntax:
String s= Environment,getExternalStorageState();
if(s.equals(Environment.MEDIA_MOUNTED)//Checking media status
File f= new File (Environment.getExternalStorageDirectory() +”/sample.txt”);
(or)
File f= new File
(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_NOTIFICATIONS)
+”/sample.txt”);
FileOutputStream fos=new FileOutputStream(f);
OutputStreamWriter osw=new OutputStreamWriter (fos);
sw.write(..);
Working with Audio and Video Files
In general any Audio and Video files can be stored in either in internal or external memory in n-
number of ways.
a) Storing Audio/Video files in External Memory
b) Storing Audio/Video files in Internal Memory
c) Retrieving Audio/Video files from Internal Memory
d) Retrieving Audio/Video files from External Memory
a) Storing Audio/Video files in External Memory
Syntax:
FileOutputStream fos= new FileOutputStream (Environment.getExternalStorageDirectory ()
+”/Folder1/Folder2/…..+/FileName.extention).
Example:
FileOutputStream fos= new FileOutputStream (Environment.getExternalStorageDirectory ()
+”/Sathya/MyMusic/Mysongs/Abc.MP3).

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b) Storing Audio/Video files in Internal Memory
Syntax:
FileOutputStream fos= OpenFileOutput (getFilesDir ()
Example:
FileOutputStream fos= OpenFileOutput (getFilesDir () +”/Sathya/MyMusic/ Abc.MP3).
c) Retrieving Audio/Video files from Internal Memory
Syntax:
FileInputStream fis= OpenFileInput (getFilesDir () ”/Folder1/Folder2/…..+/FileName.extention).
Example:
FileInputStream fos= OpenFileInput (getFilesDir () +”/Sathya/MyMusic//Abc.MP4).
d) Retrieving Audio/Video files from External Memory
Syntax:
FileInputStream fis= new FileInputStream (Environment.getExternalStorageDirectory ()
Example:
FileInputStream fis= new FileInputStream (Environment.getExternalStorageDirectory ()
+”/Sathya/MyMusic/Mysongs/Abc.MP3).
Working with Images
Images can be set to Image View or Storing in the SD Card/Internal memory with the following six
ways.
1) Getting image from drawable folder and set it in Image View.
2) Capturing image from camera and set it to Image View.
3) Getting image from External Memory and set to Image View.
4) Getting image from Internal Memory and set to Image View.
5) Getting image from External Memory and store it in to Internal Memory.
6) Getting image from Internal Memory and store it in to External Memory.
1) Getting image from drawable folder and set it in ImageView.
ImageView iv=(ImageView)findViewById(R.id.iv1);
iv.setImageResouce(r.drawable.myImage);
2) Capturing image from camera and set it to ImageView.
public void onClick(View v)
{
Intent i=new Intent(android.provider.medeastore.ACTION_IMAGE_CAPTURE);
startActivityforResul(i,REQ_CODE);
}
public void onactivityforResult(int req, int res, Intent io)
{
If(req=REQ_CODE){

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Bitmap bm=(Bitmap)io.getExtras().get(“data”);
ImageView iv=( ImageView)findViewById(R.id.image);
iv.setImageBitmap(bm);
}
}
3) Getting image from External Memory and set to ImageView.
Bitmap bm=BitmapFactory.decodefile (Environment.getExternalStorageDirectory ()
+”Sathya/MyPictures/image1.png”);
4) Getting image from Internal Memory and set to ImageView.
Bitmap bm=BitmapFactory.decodefile getFilesDir () +” MyPictures/image1.png”);
5) Getting image from External Memory and store it in to Internal Memory.
//Reading Image for External Memory
FileInputStream fis=new
FileInputStream(Environment.getExternalStorageDirectory()+”Sathya/Myimages/abc.png”);
int size=fis.available();
byte[] buffer=new byte[size];
fis.read(buffer);
//Writing Image in to Internal Memory
File F=new File(getFilesDir()+”MyImages/pictures”);
f.mkDir();
FileOutputStream fis= new FileOutputStream(getFilesDir()+”Sathya/Myimages/abc.png”);
Fos.write(buffer);
6) Getting image from Internal Memory and store it in to External Memory.
//Reading Image for Internal Memory
FileInputStream fis=new FileInputStream(getFilesDir()+”Sathya/Myimages/abc.png”);
int size=fis.available();
byte[] buffer=new byte[size];
fis.read(buffer);
//Writing Image in to External Memory
File F=new File(Environment.getExternalStorageDirectory()+”MyImages/Images”);
f.mkDir();
FileOutputStream fis= new FileOutputStream(Environment.getExternalStorageDirectory
getFilesDir()+”Sathya/Myimages/abc.png”);
Fos.write(buffer);

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3) SQLite Database
SQLite Database is the collection of data used to store permanently and securely, every android
device by default supports SQLite Database. Instead of calling Java I/O routines to access this file from
your program, you run Structured Query Language (SQL) statements. Through its helper classes and
convenience methods, Android hides some of the syntax from you, but you still need to know a bit of SQL
to use it.
SQLite Database supports various SQL commands to perform DML operations
DDL Statements
A database file can have any number of tables. A table consists of rows, and each row has a certain
number of columns. Each column of the table has a name and a data type (text string, number, and so
forth). You define these tables and column names by first running Data Definition Language (DDL)
statements. Here’s a statement that creates a table with three columns:
a) Create Table
Syntax: Create Table <Table_Name> (col1 name, data type, constraint, col2 name, data type,
constraint…etc.);
create table mytable (
_id integer primary key autoincrement, name text, phone text);
One of the columns is designated as the PRIMARY KEY, a number that uniquely identifies the row.
AUTOINCREMENT means that the database will add 1 to the key for every record to make sure it’s
unique. By convention, the first column is always called _id. The _id column isn’t strictly required for
SQLite, but later when we want to use an Android ContentProvider, we’ll need it.
public void onCreate(SQLiteDatabase db) {
createDatabase(db);
}
private void createDatabase(SQLiteDatabase db) {
db.execSQL("create table " + TABLE_NAME + "(" +
ID + “integer primary key autoincrement not null,” +
NAME + “text”
+ ");"
);
}
b) Insert Record
DML Syntax:
Insert into <TableName> (Col1, col2…etc.) Values (vol1, vol2…etc.);
insert into mytable values(null, 'Steven King' , '555-1212' );
insert into mytable values(null, 'John Smith' , '555-2345' );

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insert into mytable values(null, 'Fred Smitheizen' , '555-4321' );
The values are specified in the same order you used in the CREATE TABLE statement. We specify NULL for
_id because SQLite will figure that value out for us.
c) Update Record
Syntax: update <TableName> set col1=vol1, col2=vol2….colN=volN [where condition];
Example: Insert Student set Name=’PQR’, Marks=90.09 where Roll No=200;
d) Delete Record
Syntax: Delete from <Table_Name> [where condition];
Example: Delete from Student where Roll No=200;
e) Drop Table
Syntax: Drop <TableName>
Example: Drop Student
f) Select or Retrieve Data
Syntax: Select col1, col2…colN from <TableName> [where condition];
select * from mytable where(_id=3);
select name, phone from mytable where(name like "%smith%" );
In order to iterate over items in a database, we require an object of the Cursor class. To query the
database, we use the query method along with appropriate arguments, most importantly: the table
name, the column names for which we are extracting values.
SQLite Database Operations Mainly Depends on following predefined classes and Methods
1) SQLiteOpenHelper () – class used to create Schema and table/communication between android
application and SQLite Database.
(The constructor for the SQLiteOpenHelper class takes in a few arguments: context, database name,
CursorFactory object, version number.)
public class SqlOpenHelper extends SQLiteOpenHelper
{
public static final String DBNAME = "tasksdb.sqlite";
public static final int VERSION =1;
public static final String TABLE_NAME = "tasks";
public static final String ID= "id";
public static final String NAME="name";
public SqlOpenHelper(Context context)
{
super(context, DBNAME, null, VERSION);
}
@Override
public void onCreate(SQLiteDatabase db){

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db.execSQL(“Create Table cmd);
}
@Override
public void onUpgrade(SQLiteDatabase db){
db.execSQL(“drop table if exists TableName);
db.execSQL(“Create Table cmd);
}
Methods in SQLiteOpenHelper() class
a) getDatabaseName()
Returns the name of the SQLiteDatabase being open as given to constructor
b) getWritableDatabase()
Crete and/or open a database that will be write mode or read mode
To get a handle on the SQL database you created, instantiate the class inheriting SQLiteOpenHelper:
SqlOpenHelper helper = new SqlOpenHelper(this);
SQLiteDatabase database= helper.getWritableDatabase();
Now, the SQLiteDatabase database can be used to load elements stored in the database, update and
insert elements to it.
c) getReadableDatabase()
Database opens only for read mode
d) onCreate(SQLiteDatabase)
Called when the database is created first time
e) onUpgrade(SQLiteDatabase, int oldVersion, int newVersion)
Called when the database is need to upgrade
f) onDowngrade(SQLiteDatabase, int oldVersion, int newVersion)
Called when the database is need to downgrade
g) close()
Close any opened database object
2) SQLiteDatabase() – class used to perform DML Operations
Methods in SQLiteDatabase() class
h) Insert()
Used to insert record into Database return type Long (returns row id)
Syntax:
Using insert () method and passing an object of ContentValues class. ContentValues provides
something like a key-value pair,
*String table = TABLE_NAME
* nullColumnHack = null values will added in the columns
* ContentValues = Container holds the list of columns and values
ContentValues cv=new ContentValues();
cv.put(col1,vol1);
cv.put(col2,vol2);
SQLiteDatabase db=getWritableDatabase();
db.insert (“MyTable” null, cv);

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i) update()
Used to update one or more records into database table return type +int
update(String table, ContentValues, String Where Clause , String[]Where args);
ContentValues cv=new ContentValues();
cv.put(_id,vol1);
cv.put(col2,vol2);
cv.put(col3,vol3);
String args [] = {1,2,3}
db.update(“MyTable”, cv, “_id=?” args);
or
db.update(“MyTable”,cv,null,null) all records will be updated
j) delete()
Used to delete one or more records from database table
delete(String table, String Where Clause , String[]Where args);
String args [] = {1,3}
db.delete(“MyTable”,”_id=?”, args); //1,3 records deleted
k) query() – return Cursor
Used to select one or more records from database table,
queryString table, String Columns, String Selection, String[]Selection args, String Having, String
Orderby, String groupby));
String columns[]={col1, col2};
String args [] = {1,2};
Cursor c=SQLiteDatabase.query(“MyTable”, columns[], ”_id=?”, args, null, null, null );
return c;
//1,2 records col1,col2 retrieved
l) rawQuery() – return Cursor
Used to select records from the table similar to query() but it allows direct SQL Commands
rawquery(“String SQL cmds, String[] selection args);
String args [] = {1,2};
Cursor c=SQLiteDatabase.rawquery(“select *from MyTable” where “_id=?”, args);
return c;
3) execSQL(String sql)
Used to execute a single SQL statement other than SELECT statement
execSQL(“SQL Comands”);
4) Environment .getDataDirectory() – this method used get the root path of SQLite Database
5) getPath() –Used to get the path of the database
6) getVersion() - used to get the database version
7) isOpen() – returns true the database is currently open
8) deleteDatabase(File file) - delete the database file

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9) getMaximumSize() - get the size of the database
10) SimpleCursorAdapter(): to display the content
Understanding the SimpleCursorAdapter
✓ this: Context: The context that is associated with the adapter.
✓ R.layout.- layout: The layout resource identifier that defines the file to use for this list item.
✓ reminderCursor - c: The database Cursor.
✓ from - from: An array of column names that are used to bind data from the cursor to the view.
✓ to - - to: An array of view IDs that should display the column information from the from parameter.
✓ The to and from parameters create a mapping informing the SimpleCursorAdapter how to map data in
the cursor to views in the row layout
14. Content Provider
Often the application generates data, which can be processed and analyzed by another
application. What is the safest way to achieve this, without giving direct access to our application's
database?
Writing a custom Content Provider is the Android way to allow other applications to access data
generated by our app.
ContetnProvider is a predefined android element used to make private data of SQLite database as public
data, so that multiple applications can be able to access that data.
Content providers allow other applications to access the data generated by our app. For a custom
content provider, we need to have the app database built up and we will be providing the wrapper over it
for other applications. To make other apps aware that a content provider is available, declare it in
In Android contentprovider classified into two types
1) Predefined ContentProvider
2) User defined ContentProvider
AndroidManifest.xml as:
<provider android:authorities="com.example.android.contentprovider"
android:name="MyContentProvider" />
Any piece of information managed by a ContentProvider is addressed through a URI that looks like this:
content://authority/path/id
where:
• content:// is the standard required prefix.
• authority is the name of the provider. Using your fully qualified package name is recommended to
prevent name collisions.
• path is a virtual directory within the provider that identifies the kind of data being requested.

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• id is the primary key of a specific record being requested. To request all records of a particular type,
omit this and the trailing
slash. Android comes with several providers already built in, including the following:
• content://browser
To share the browser history by multiple applications
Predefined class : android.provider.Browser.BookMarkColumns
Uri: Browesr.BOOKMARKS_URI
Manifest permission “ com.android.browser.permission.READ_HISTORY_BOOKMARKS”
• content://contacts
anroid.provider.ContactsContract.Contacts”
uri: “content://contacts/people
Manifest permission “ com.android.permission.READ_CONTACTS”
• content://calllog
anroid.provider.CallLog.Calls”
uri: “CallLog.Calls.CONTENT_URI”
Manifest permission “ com.android.permission.READ_CONTACTS”
To invoke with predefined ContentProvider we need to Activity.managedQuery() method
managedQuery()
It is a predefined method of Activity class can be used to move the data from Database to
ContentProvider (every content provider by default acting as result set or cursor adapter view, it is a
temporary memory Location in the primary memory) it will returns cursor
Syntax: managedQuery(Content uri. String[] projection, String Selection, String[] selection args, orderby);
*String[] projection : required fields from the table
*String Selection : where condition
3) User Defined ContentProvider
Here the name refers to the class MyContentProvider which extends ContentProvider class. You need to
override the following methods in this class.
public MycontentProvider extends ContentProvider
{
public void onCreate(){
}
public int delete(Uri, String, String[]);{
}
public String getType(Uri){
}
public Long insert(Uri, ContentValues);{
}

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public Cursor query(Uri, String[], String, String[], String){
}
public int on pdate(Uri, ContentValues, String, String[]){
}
Manifest provider
<Provider android:exported=”true”
android:name=”.MyProvider”
authorities=”com.bened”/>
Every user defined contentprovider class should have user defined SQLiteOpenHelper() to manage user
defined SQLiteDatabase
To invoke with user defined ContentProvider we need to contentResolver() class
contentResolver ();
This can be used to invoke with user defined ContentProvider
contentResolver cr=super.getcontentResolver();
Every user defined content provider can invoke with following method of contentResolver class
Cursor cs=cr.query(uri,projection,selection,selection arguments, orderby);
Any user define ContentProvider mus use the following fixed uri
“content://com.bebed/contentable”
15) BroadcastReceiver
Broadcast Receiver is a class in android used to intimate to the end user whenever any information or
data is received form any application from the same device or another device.
public class <classname> extends BroadcastReceiver{
@override
public void onReceive(context context, Intent intent)
{
:::::
}
}
Manifest : <receiver android:name=”.BCRCN”/>
16) Networking
a) Bluetooth
Used to connect other devices for sharing data
Predefined class BluetoothAdapter();
Manifest permissions =”BLUETTOTH_ADMIN”
= “BLUETOOTH”
Methods
i. getDefaultAdapter()

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This was returns BluetoothAdapter class objref with default properties of physical Adapter device( if
that is working properly) otherwise returns null.
BluettothAdapter ba= BluetoothAdapter.getDefaultAdapter();
If(ba==null)
{
//Bluetooth Adapter is not supported
}else
//Bluetooth supported
}
ii. isEnabled()
If it returns TRUE Bluetooth adapter is currently enabled and ready to use otherwise returns FALSE
iii. enable()
If it returns TRUE Bluetooth enabled otherwise returns FALSE
iv. disable()
If it returns TRUE Bluetooth disabled successfully otherwise returns FALSE
v. isDiscovering()
If it returns TRUE Bluetooth adapter is currently in discovering process (searching)
vi. startDiscovering()
Returns TRUE whenever local Bluetooth Adapter start the remote device discovering process
vii. cancelDiscovering()
If it returns TRUE Bluetooth adapter discovering process is canceled
viii. listenUsingRfcommWithServiceRecord(String name, UUID uuid)
This method can be used to request to pair with other device with secured connection (with protect
with password request)
ix. listenUsingosecureRfcommWithServiceRecord(String name, UUID uuid)
This method can be used to request to pair with other device without secured connection
x. getBoundedDevices()
Returns set<BluetoothDevices> object that are Bounded (paired) to the local adapter
xi. getAddress()
Returns the hardware Address of the local Bluetooth Adapter in String format
xii. getName()
Get the user friendly name of the local Bluetooth
xiii. setName()
Returns TRUE if the given user friendly name is set to local Bluetooth successfully
Bluetooth operations not only can be performed using predefined methods of Bluetooth adapter
class but also using implicit Intent by passing default actions of same Bluetooth adapter class
Ex1: Intent enableIntent=new Intent(BluttothAdapter.ACTION_REQUEST_ENABLE);
startActivityforResult(enableintent, 1);
Ex2: Intent discoverable=new Intent(BluttothAdapter.ACTION_REQUEST_DISCOVERABLE);
Discoverable.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 3000);
startActivityforResult(dicoverable, 1);
b) Wi-Fi
Used to connect Local Systems for sharing of data
Predefine service class WifMangaer wm=(wifiManager)getSystemService(WIFI_SERVICE);

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Manifest permissions =”ACCESS_WIFI_STATE”
= “UPDATE_DEVICE_STATE”
= “CHANGE_DEVICE_STATE”
Methods
i. setWifiEnabled(Boolean enabled)
Used to enable and disable wifi
ii. startScan()
Used to scan wifi networks
iii. getScanResuluts()
Returns the list of the latest scanned Networks returns List<ScanedReults)
iv. isWifiEnabled()
Returns TRUE if Wi-FI is enabled
v. addNetwork(Wificonfiguration config)
Used to add the new configured networks
vi. enableNetwork(int netId)
Allows previously configured networks
vii. disableNetwork(int netId)
Used to disable configured networks
viii. disconnect()
Used to disconnect the currently associated Wi-Fi
ix. getConnectionInfo()
Returns the dynamic information about current Wi-Fi connection
x. getConfiguredNetworks()
Returns all the list of configured Networks
xi. updateNetwork(WifiConfiguration confg)
Used to update networks description of an existing configured network
xii. reconnect()
Used to reconnect the currently active network if it is disconnected
c) GPRS
Mobil to connect any server system for sharing of data
Predefined classes a) WebView()-Used to load the web pages on layout files
b) WebSettings()-Used to enable/disable default settings
public void GPRSConnection extends Activity{
{
supre.onCreate(b);
setContentView(R.layout.main);
WebView w=(WebView)findViewById(R.id.webview);
w.loadUrl(http://www.google.com);
WebSettings ws=w.getSettings();
ws.setJavaScriptenable(true);
ws.setLoadWithOverViewMode(true);
::::::::::::
}
}
HttpUrlConnection()

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It is a predefined class java.net package used to establish connection between android applications to
HTTP Server either for sending the request of to get the response from the Server.
Steps to Send the Request (data) from android application to Server
 Take Internet Permission in Manifest File
 Design any user defined layout (to give the provisioning to the end user to send data).
 Design Activity class which must contain following code
a) Create Object for HttpUrlConnection()
b) Connect() - Establish connection between client and server
HttpUrlConnection huc=new HttpUrlConnection(url);
*url = It should be used to taking permission from server provider
huc.Connect();
c) Request data from Server with following code
OutputStream os=huc.getOutputStream();
DataOutputStream dos=new DataOutputStream(os);
Steps to get the Response (data) from Server to android application
 Design user defined layout to display response data
 Design Activity class
 Read response data from server using InputStream Class
InputStream is=huc.getInputStream();
DataInputStream dis=new DataInputStream(is);
dis.readLine();
is.close();
d) GPS
GPS is one of the mobile technologies used to find the current location of the device (Tracking of device)
Manifest permissions: INTERNET
ACCESS_COARS_LOCATION
ACCES_FINE_LOCATION
Location Based application Classes
1) LocationManager()
Used to find the current location of the device
LocationManager lm=(LocationManager)getSystemService(context.LOCATION_SERVICE);
Methods
i. requestLocationUpdate(--)
Location Manager Class mainly depends upon LocationListener Interface, it is responsible to perform
dynamic operations whenever the location settings has been changed
Methods of LocationListener
i. onLocationChanged()
This will be called whenever current location has been changed
ii. onProviderDisabled(String provider)
This will be called whenever GPS is disabled.
iii. onProviderEnabled(String provider)
This will be called whenever GPS is enabled.
iv. onStatusChanged(String provider, int Status, Bundle Extra)
This will be executed whenever current network status has been changed
2) MapActivity()
3) MapView()
4) MapController()
5) GeoPoint()

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Android Interview Questions and Answers
1. What is an Activity class and how to register activity in manifest file?
2. What is an Intent class and write the logic to switch from one activity to other activity by passing
name and address of student?
3. What is the difference between bounded service and un-bounded service?
4. Write the logic to play an audio song in the background of an android application?
5. Write the logic to enable Wi-Fi service through android application?
6. Write the logic to find current location using LocationManager Service?
7. Explain the manifest file?
8. What is the difference between SQLiteOpenHelper and SQLiteDatabase classes?
9. What is the difference between WebView and MapView?
10. What are the permissions should be taken while working with SD-card?
11. What is widget?
12. What is the function of an intent filter?
13. What is the difference between onStop() and onPause()?
14. Explain entire lifetime, visible lifetime & foreground lifetime?
15. Write the various launch modes of an activity?
16. What is the use of layout-weight in XML?
17. What is the difference between Activity context and Application Context?
18. What is meant by View Group in android?
19. What is the difference between Send Sticky Broadcast & send Broadcast?
20. What is the usage of content resolver?
21. Do we need to register content provider in androidmanifest.XML?
22. What is NDK & Mention the use of NDK?
23. Write the structure of Manifest file?
24. What are the terms of dp, px, sp?
25. What is nine-patch image?
26. What is the usage of trace view & hierarchy view?
27. What is latest version of android?
28. Android: id="@+id/my button---------->what is + symbol?why we use that?
29. How to install test app .apk file into phones?
30. Activity Life Cycle?
31. Different Kinds of Intents?
32. Check the knowledge on AndroidManifest file, For example: Why do we need this file, What is the
Role of this file in Android app development?.
33. Different kinds of context?
34. Kinds of Log debugger and Debugger Configuration
35. How to debug the application on real device.
36. How do you ensure that the app design will be consistent across the different screen resolutions
37. Can you able to build custom views and how?
38. What is onCreate (Bundle savedInstanceState), Have you used savedInstanceState when and
why?
39. What is localization and how to achieve?
40. Can you able to build custom views and how?
41. When to use a service?
What is needed to make a multiple choice list with a custom view for each row?

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Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1".
That is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.
Explain about the exceptions of Android.
The following are the exceptions that are supported by Android
 InflateException : When an error conditions are occurred, this exception is thrown
 Surface.OutOfResourceException: When a surface is not created or resized, this exception is thrown
 SurfaceHolder.BadSurfaceTypeException: This exception is thrown from the lockCanvas() method, when
invoked on a Surface whose is SURFACE_TYPE_PUSH_BUFFERS
 WindowManager.BadTokenException: This exception is thrown at the time of trying to add view an
invalid WindowManager.LayoutParamstoken
 What’s the difference between file, class and activity in android?
File – It is a block of arbitrary information, or resource for storing information. It can be of any type.
Class – Its a compiled form of .Java file . Android finally used this .class files to produce an executable apk
Activity – An activity is the equivalent of a Frame/Window in GUI toolkits. It is not a file or a file type it is
just a class that can be extended in Android for loading UI elements on view.
 What is a Sticky Intent?
sendStickyBroadcast() performs a sendBroadcast (Intent) that is “sticky,” i.e. the Intent you are sending
stays around after the broadcast is complete, so that others can quickly retrieve that data through the
return value of registerReceiver (BroadcastReceiver, IntentFilter). In all other ways, this behaves the
same as sendBroadcast(Intent).
 One example of a sticky broadcast sent via the operating system is ACTION_BATTERY_CHANGED. When
you call registerReceiver() for that action — even with a null BroadcastReceiver — you get the Intent that
was last broadcast for that action. Hence, you can use this to find the state of the battery without
necessarily registering for all future state changes in the battery.
 Describe Android Application Architecture.
Android Application Architecture has the following components:
• Services – like Network Operation
• Intent – To perform inter-communication between activities or services
• Resource Externalization – such as strings and graphics
• Notification signaling users – light, sound, icon, notification, dialog etc.
• Content Providers – They share data between applications
 What kind of open-source project is Android?
Google oversees the development of the core Android open-source platform, and works to create robust
developer and user communities. For the most part the Android source code is licensed under the
permissive Apache Software License 2.0, rather than a “copyleft” license. The main reason for this is
because our most important goal is widespread adoption of the software, and we believe that the ASL2.0
license best achieves that goal.
 You can find more information on this topic at our Project Philosophy and Licensing pages.
 Introduction Android:

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 Android Introduction:
 Android is an open source operating system for mobile devices that includes middleware and key
applications, and uses a modified version of the Linux kernel. It was initially developed by Android Inc.
 It allows developers to write managed code in the Java language, controlling the device via Google-
developed Java libraries…..The Android SDK includes a comprehensive set of development tools . These
include a debugger, libraries, a handset emulator (based on QEMU), documentation, sample code, and
tutorials. Currently supported development platforms include x86-architecture computers running Linux
,Mac OS X 10.4.8 or later, Windows XP or Vista. Android does not use established Java standards, i.e. Java
SE and ME. This prevents compatibility among Java applications written for those platforms and those for
the Android platform. Android only reuses the Java language syntax, but does not provide the full-class
libraries and APIs bundled with Java SE or ME
 What is android?
 Android is a software stack for mobile devices which has Operating System, middleware and some key
applications. The application executes within its own process and its own instance of Dalvik Virtual
Machine. Many Virtual Machines run efficiently by a DVM device. DVM executes Java language?s byte
code which later transforms into .dex format files.
 What are the advantages of Android?
The following are the advantages of Android:
* Features like weather details, live RSS feeds, opening screen, icon on the opening screen can be
customized
* The customer will be benefited from wide range of mobile applications to choose, since the monopoly
of wireless carriers like AT&T and Orange will be broken by Google Android.
* Innovative products like the location-aware services, location of a nearby convenience store etc., are
some of the additive facilities inAndroid.
Components can be reused and replaced by the application framework.
*Optimized DVM for mobile devices
*SQLite enables to store the data in a structured manner.
*Supports GSM telephone and Bluetooth, WiFi, 3G and EDGE technologies
*The development is a combination of a device emulator, debugging tools, memory profiling and plug-in
for Eclipse IDE.
 Features of Android :
Application framework enabling reuse and replacement of components Dalvik virtual machine
optimized for mobile devices
Integrated browser based on the open source WebKit engine
Optimized graphics powered by a custom 2D graphics library; 3Dgraphics based on the OpenGL ES 1.0
specification (hardware acceleration optional)
SQLite for structured data storage
Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG,
PNG, GIF)
GSM Telephony (hardware dependent)
Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
Camera, GPS, compass, and accelerometer (hardware dependent)

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Rich development environment including a device emulator, tools for debugging, memory and
performance profiling, and a plugin for the Eclipse IDE.
 Explain about the Android Exceptions?
 The following are the exceptions that are supported by Android
* InflateException : When an error conditions are occurred, this exception is thrown
* Surface.OutOfResourceException: When a surface is not created or resized, this exception is thrown
* SurfaceHolder.BadSurfaceTypeException: This exception is thrown from the lockCanvas() method,
when invoked on a Surface whose is SURFACE_TYPE_PUSH_BUFFERS
* WindowManager.BadTokenException:
 This exception is thrown at the time of trying to add view an invalid
WindowManager.LayoutParamstoken.
 Describe the APK format?
The APK file is compressed the AndroidManifest.xml file, application code (.dex files), resource files, and
other files. A project is compiled into a single .apk file.
 What is an adb ?
Android Debug Bridge, a command-line debugging application shipped with the SDK. It provides tools to
browse the device, copy tools on the device, and forward ports for debugging.
 What is an Application ?
A collection of one or more activities, services, listeners, and intent receivers. An application has a single
manifest, and is compiled into a single .apk file on the device.
 What is a Content Provider ?
A class built on ContentProvider that handles content query strings of a specific format to return data in a
specific format. See Reading and writing data to a content provider for information on using content
providers.
 What is a Dalvik ?
The name of Android’s virtual machine. The Dalvik Virtual Machine is an interpreter-only virtual machine
that executes files in the Dalvik Executable (.dex) format, a format that is optimized for efficient storage
and memory-mappable execution. The virtual machine is register-based, and it can run classes compiled
by a Java language compiler that have been transformed into its native format using the
included “dx” tool.
 The Virtual Machine runs on top of Posix-compliant operating systems, which it relies on for underlying
functionality (such as threading and low level memory management). The Dalvik core class library is
intended to provide a familiar development base for those used to programming with Java Standard
Edition, but it is geared specifically to the needs of a small mobile device.
 What is Drawable?
A compiled visual resource that can be used as a background, title, or other part of the screen. It is
compiled into an android.graphics.drawable subclass.
 What is Intent?
A class (Intent) that contains several fields describing what a caller would like to do. The caller sends this
intent to Android’s intent resolver, which looks through the intent filters of all applications to find the
activity most suited to handle this intent. Intent fields include the desired action, a category, and a data
string, the MIME type of the data, a handling class, and other restrictions.
 What is an Intent Filter?
Activities and intent receivers include one or more filters in their manifest to describe what kinds of
intents or messages they can handle or want to receive. An intent filter lists a set of requirements, such
as data type, action requested, and URI format, that the Intent or message must fulfill. For Activities,
Android searches for the Activity with the most closely matching valid match between the Intent and the
activity filter. For messages, Android will forward a message to all receivers with matching intent filters.

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 What is an Intent Receiver?
An application class that listens for messages broadcast by calling Context.broadcastIntent
 What is a Layout resource?
An XML file that describes the layout of an Activity screen.
 What is a Manifest?
An XML file associated with each Application that describes the various actives, intent filters, services,
and other items that it exposes.
 What is a Resource?
A user-supplied XML, bitmap, or other file, entered into an application build process, which can later be
loaded from code. Android can accept resources of many types; see Resources for a full description.
Application-defined resources should be stored in the res/ subfolders.
 What is a Service?
A class that runs in the background to perform various persistent actions, such as playing music or
monitoring network activity.
 What is a Theme?
A set of properties (text size, background color, and so on) bundled together to define various default
display settings. Android provides a few standard themes, listed in R.style (starting with “Theme_”).
 What is a URIs?
Android uses URI strings both for requesting data (e.g., a list of contacts) and for requesting actions (e.g.,
opening a Web page in a browser). Both are valid URI strings, but have different values. All requests for
data must start with the string “content: //”. Action strings are valid URIs that can be handled
appropriately by applications on the device; for example, a URI starting with “http://” will be handled by
the browser.
 Can I write code for Android using C/C++?
Yes, but need to use NDK
Android applications are written using the Java programming language. Android includes a set of core
libraries that provides most of the functionality available in the core libraries of the Java programming
language. Every Android application runs in its own process, with its own instance of the Dalvik virtual
machine. Dalvik has been written so that a device can run multiple VMs efficiently. The Dalvik VM
executes files in the Dalvik Executable (.dex) format which is optimized for minimal memory footprint.
The VM is register-based, and runs classes compiled by a Java language compiler that have been
transformed into the .dex format by the included “dx” tool.
Android only supports applications written using the Java programming language at this time.
 What is an action?
A description of something that an Intent sender desires.
 What is activity?
A single screen in an application, with supporting Java code.
 What is intent?
A class (Intent) describes what a caller desires to do. The caller sends this intent to Android’s intent
resolver, which finds the most suitable activity for the intent. E.g. opening a PDF file is intent, and the
Adobe Reader is the suitable activity for this intent.
 How is nine-patch image different from a regular bitmap?
It is a resizable bitmap resource that can be used for backgrounds or other images on the device. The
NinePatch class permits drawing a bitmap in nine sections. The four corners are unscaled; the four edges
are scaled in one axis, and the middle is scaled in both axes.
 What languages do Android support for application development?
Android applications are written using the Java programming language.
 What is a resource?

P a g e | 37
A user-supplied XML, bitmap, or other file, injected into the application builds process, which can later be
loaded from code.
 How will you record a phone call in Android? How to get a handle on Audio Stream for a call in
Android?
Permissions.PROCESS_OUTGOING_CALLS: Allows an application to monitor, modify, or abort outgoing
calls.
1. Explain the Architecture of android?
a. Top -> Applications (Contacts, Browser, Phone, etc)
b. Below Applications -> Application Framework(Activity Manager, Window Manager, Content Providers,
View System, Package manager,
Telephony manager, Resource, Notification, Location managers)
c. Below Application Framework -> System Libraries(Like Sqlite, webkit, SSL, OpenGL, Media Framework
etc) & Android Runtime( Core Libraries and DVM)
d. At last -> Linux Kernel (which composed of drivers like display, camera etc.)
2. What is an Activity?
A single screen in an application, with supporting Java code, An activity presents a visual user interface
for one focused endeavor the user can undertake. For example, an activity might present a list of menu
items users can choose from or it might display photographs along with their captions. Each one is
implemented as a subclass of the Activity base class.
3. What are fragments in Android Activity?
A Fragment represents a behavior or a portion of user interface in an Activity. And it is a self-contained
component with its own UI and lifecycle.
4. What is Intent?
A class (Intent) which describes what a caller desires to do. The caller will send this intent to
Android's intent resolver, which finds the most suitable activity for the intent. E.g. opening a PDF
document is an intent, and the Adobe Reader apps will be the perfect activity for that intent (class).
5. What is a Sticky Intent?
sendStickyBroadcast() performs sendBroadcast(Intent) known as sticky, i.e. the Intent you are
sending stays around after the broadcast is complete, so that others can quickly retrieve that data
through the return value of registerReceiver(BroadcastReceiver, IntentFilter). In all other ways, this
behaves the same as sendBroadcast(Intent). One example of a sticky broadcast sent via the operating
system is ACTION_BATTERY_CHANGED. When you call registerReceiver() for that action -- even with a
null BroadcastReceiver -- you get the Intent that was last broadcast for that action. Hence, you can use
this to find the state of the battery without necessarily registering for all future state changes in the
battery.
6. What is an action?
A description of something that an Intent sender desires
7. What is a service?
A service doesn’t have a visual user interface, but rather runs in the background for an indefinite period
of time.
For example, a service might play background music as the user attends to other matters, or it might
fetch data over the network or calculate something and provide the result to activities that need it.
Each service extends the Service base class.
8. What is a Broadcast receiver?
A broadcast receiver is a component that does nothing but receives and reacts to broadcast
announcements.

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For example, announcements that the timezone has changed, that the battery is low or that the user
changed a language preference.
All receivers extend the BroadcastReceiver base class.
Broadcast receivers do not display a user interface. However, they may start an activity in response to the
information they receive,or they may use the Notification Manager to alert the user like(flashing the
backlight, vibrating the device, playing a sound).
9. What is a content provider?
A content provider makes a specific set of the application’s data available to other applications.The
content provider extends the ContentProvider base class to implement a standard set of methods that
enable other applications to retrieve and store data of the type it controls. However, applications do not
call these methods directly. Rather they use a ContentResolver object and call its methods instead.
10. What language does Android support for application development?
Android applications are written using the Java programming language.
11. What is a resource?
A user-supplied XML, bitmap, or other file, injected into the application build process, which can later be
loaded from code.
12. How do you define the user interface?
XML Format is the best.
13. Does Android support the Bluetooth serial port profile?
Yes.
14. Can an application be started on power up?
Yes.
15. What is the APK format?
The APK file is compressed AndroidManifest.xml file with extension .apk. It also includes the application
code (.dex files), resource files, and other files which are compressed into a single .apk file.
16. What is .dex extension ?
Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single
.apk file on the device. .dex files can be created by automatically translating compiled applications
written in the Java programming language.
17. How to Translate in Android?
The Google translator translates the data of one language into another language by using XMPP to
transmit data. You can type the message in English and select the language which is understood by the
citizens of the country in order to reach the message to the citizens.
18. What is needed to make a multiple choice list with a custom view for each row?
Multiple choice list can be viewed by making the CheckBox android:id value be “@android:id /text1".
That is the ID used by Android for the CheckedTextView in simple_list_item_multiple_choice.
19. What dialog boxes are supported in android?
Android supports 4 dialog boxes:
Alert Dialog: An alert dialog box supports 0 to 3 buttons and a list of selectable elements, including
check boxes and radio buttons. Among the other dialog boxes, the most suggested dialog box is the
alert dialog box.
Progress Dialog: This dialog box displays a progress wheel or a progress bar. It is an extension of Alert
Dialog and supports adding buttons.
DatePickerDialog: This dialog box is used for selecting a date by the user.
TimePickerDialog: This dialog box is used for selecting time by the user.
20. Explain about the exceptions of Android?

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The following are the exceptions that are supported by Android
* InflateException : When an error conditions are occurred, this exception is thrown
* Surface.OutOfResourceException: When a surface is not created or resized, this exception is thrown
* SurfaceHolder.BadSurfaceTypeException: This exception is thrown from the lockCanvas() method,
when invoked on a Surface whose is SURFACE_TYPE_PUSH_BUFFERS
* WindowManager.BadTokenException: This exception is thrown at the time of trying to add view an
invalid WindowManager.LayoutParamstoken.
21. What are the features of Android?
*Components can be reused and replaced by the application framework.
*Optimized DVM for mobile devices
*SQLite enables to store the data in a structured manner.
*Supports GSM telephone and Bluetooth, WiFi, 3G and EDGE technologies
*The development is a combination of a device emulator, debugging tools, memory profiling and
plug-in for Eclipse IDE.
22. How will you record a phone call in Android? or How to handle on Audio Stream for a call in Android?
Permissions.PROCESS_OUTGOING_CALLS: Will Allows an application to monitor, modify, or abort
outgoing calls. So through that we can monitor the Phone calls.
23. What's the difference between class, file and activity in android?Class - The Class file is compiled from
.java file. Android will use this .class file to produce the executable apk.File - It is a block of resources,
srbitrary information. It can be any file type. Activity - An activity is the equivalent of a Frame/Window in
GUI toolkits. It is not a file or a file type it is just a class that can be extended in Android for loading UI
elements on view.
24. What are the advantages of Android?
The following are the advantages of Android:
* The customer will be benefited from wide range of mobile applications to choose, since the
monopoly of wireless carriers like Orange and AT&T will be broken by Google Android.
* Features like weather details, live RSS feeds, opening screen, icon on the opening screen can be
customized.
* Innovative products like the location-aware services, location of a nearby convenience store etc.,
are some of the additive facilities in Android.
25. How many ways data stored in Android?
1. SharedPreferences 2. Internal Storage 3. External Storage 4. SQLite Database 5. Network
connection
26. What is View in Android?
Views are the base class for all visual interface elements (commonly known as controls or widgets).
All UI controls, including the layout classes, are derived for View.
27. What View Group in Android?
View Groups are extensions of the View class that can contain multiple child View.Extend the ViewGroup
class to create compound controls made up of interconnected child Views.
28. What is Pending Intent?
The PendingIntent class provides a mechanism for creating Intents that can be fired by another
application at a later time. A pending Intent is commonly used to package an Intent will be fired in

P a g e | 40
response to a future event, such as a widget View being clicked or a Notification being selected from the
notification panel.
29. What is Adapter?
Adapters are bridging classes that bind data to Views (such as List Views) used in the user interface.The
adapter is responsible for creating for creating the child Views used to represent each item within the
parent View, and providing access to the underlying data.
30. What is a DDMS?
Dalvik Debug Monitor Service, a GUI debugging application shipped with the SDK. It provides screen
capture, log dump, and process examination capabilities.
31. What is an adb?
Android Debug Bridge, a command-line debugging application shipped with the SDK. It provides tools to
browse the device, copy tools on the device, and forward ports for debugging.
32. Explain Structure of Manifest.xml File?
Every application must have an AndroidManifest.xml file (with precisely that name) in its root directory.
The manifest presents essential information about the application to the Android system, information
the system must have before it can run any of the application's code.
Following Are the Contents of manifest.xml File.
• Application
• Activity
• Services
• Broadcast Receivers
• Permissions
• Instrumentation
• Minimum API Level
33. How will you pass the data to sub-Activities?
We can use Bundles to pass data to sub-activities. There are like HashMaps that and take trivial
data types. These Bundles transport information from one Activity to another.
code -
Bundle b = new Bundle();
b.putString("EMAIL", "abc@xyz.com");
i.putExtras(b); // where i is the intent
34. What is AAPT?
AAPT is short for Android Asset Packaging Tool. This tool provides developers with the ability to deal with
zip-compatible archives, which includes creating, extracting as well as viewing its contents.
35. What is the importance of having an emulator within the Android environment?
The emulator lets developers “play” around an interface that acts as if it were an actual mobile device.
They can write and test codes, and even debug. Emulators are a safe place for testing codes especially if it
is in the early design phase.
36. What is Orientation?
Orientation, which can be set using setOrientation(), dictates if the LinearLayout is represented as a row
or as a column. Values are set as either HORIZONTAL or VERTICAL.

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37. What is ANR?
ANR is short for Application Not Responding. This is actually a dialog that appears to the user whenever
an application have been unresponsive for a long period of time.
38. How can the ANR be prevented?
One technique that prevents the Android system from concluding a code that has been responsive for a
long period of time is to create a child thread. Within the child thread, most of the actual workings of the
codes can be placed, so that the main thread runs with minimal periods of unresponsive times.
39. When does ANR occur?
The ANR dialog is displayed to the user based on two possible conditions. One is when there is no
response to an input event within 5 seconds, and the other is when a broadcast receiver is not done
executing within 10 seconds.
40. What is AIDL?
AIDL, or Android Interface Definition Language, handles the interface requirements between a client and
a service so both can communicate at the same level through interprocess communication or IPC. This
process involves breaking down objects into primitives that Android can understand. This part is required
simply because a process cannot access the memory of the other process.
41. What data types are supported by AIDL?
AIDL has support for the following data types:
-string
-charSequence
-List
-Map
-all native Java data types like int, long, char and Boolean.
42. What is the difference between a regular bitmap and a nine-patch image?
In general, a Nine-patch image allows resizing that can be used as background or other image size
requirements for the target device. The Nine-patch refers to the way you can resize the image: 4 corners
that are unscaled, 4 edges that are scaled in 1 axis, and the middle one that can be scaled into both axes.
43. What do you think are some disadvantages of Android?
Given that Android is an open-source platform, and the fact that different Android operating systems
have been released on different mobile devices, there’s no clear cut policy to how applications can adapt
with various OS versions and upgrades. One app that runs on this particular version of Android OS may or
may not run on another version. Another disadvantage is that since mobile devices such as phones and
tabs come in different sizes and forms, it poses a challenge for developers to create apps that can adjust
correctly to the right screen size and other varying features and specs.
44. What are the multimedia features involved in making Android popular?
There is the demand for the rich multimedia that involves many features that are used till now to
make the Android market more popular in all the phases. The application includes the following:
• Mixable audio effects – developer can easily create audio environments using the API key that is
provided with it like creating equalization, bass boost, headphone feature, etc. The android provide the
tools that can be used to mix the audio effects and apply it.
• There is also support for new media formats like VP8 open video compression format that uses a

P a g e | 42
container format that can run on all the platforms and add the support for AAC and AMR encoding. The
applications provided allow higher quality video to be captured.
• The application allows the access to multiple cameras that allows the use of APIs to include the camera
and its properties in one. The platform provides the application to include the camera with high and low
resolution.
45. What are the different data types used by Android?
The data can be passed between many services and activities using the following data types:
• Primitive Data Types: are used to share the activities and services of an application by using the
command as Intent.putExtras(). This primitive data passes the command to show the persistent data
using the storage mechanism. These are inbuilt data types that are used with the program. They provide
simple implementation of the type and easy to use commands.
• Non-Persistent Objects: are used to share complex and non-persistent objects. These are user-defined
data types that are used for short duration and are also recommended to be used. These types of objects
allow the data to be unique but it creates a complex system and increase the delay.
46. What are the methods to avoid memory leaks in Android?
Android applications are well bundled with the memory but they have a drawback of running lots
of application that keeps in the memory to make the processing faster. The more application in the
memory, the faster will be the switch between the applications. The memory leaks can be avoided by
changing the context. The context is used for many operations but it is used to access the resources on
android. The widgets have a context parameter in their constructors. There are mainly two types of
context: either activity or application. The program is as follows:
@Override
protected void onCreate(Bundle state) {
super.onCreate(state);
TextView label = new TextView(this);
label.setText("Test memory leak");
setContentView(label);
}
if the context is having leaks in it then the activity then there is a possibility of the leaks of memory. The
leaking of the entire activity can be checked. The system will automatically create and destroy one of the
activities by default. Android will reload the application by using the rotation policy. And it will keep the
entire static field maintained.
47. What are the various ways an Android developer can apply multi-threading to their app? Be specific, and
give examples.
Since Android uses the Java language it provides all the normal threading mechanisms as all Java-
based implementations.
You create a Thread by either (a) sub-classing the Thread class with your own and over-loading the
run() method to perform your background task, or (b) you create an instance of the Thread class by
giving it an instance of the Runnable interface, and overload the run() method of that interface to
perform your background task. Option (b) is preferred by far in most circumstances.

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Android, however, provides additional threading mechanisms over and above those provided by Java,
and they tend to resolve some of the most interesting dilemmas in Java programming.
In Android you have the following additional mechanisms:
1) AsyncTask
2) Handler
3) runOnUiThread()
4) IntentService (for Service implementations)
So, depending upon what your needs are, you can greatly simplify your code by opting for
the use of one of these mechanisms.
For instance, the AsyncTask class provides a very nice encapsulation of creating a Java
Thread, providing thread-correct calls for pre/post processing, and automatically uses a thread pool
behind the scenes to efficiently use thread resources. All this and provides a very simple 4 method
sub-classing interface where you can write just your background code within a single method, and
the AsyncTask class will handle cross-thread messaging for you. You have to know, however, that
AsyncTask uses a Handler instance internally, so if you're launching this from a Thread that doesn't
use a MessageQueue, then this may not work properly for you.
runOnUiThread() does just what it says, it will take a Runnable instance, and run it in the
thread space of the main, or "UI", thread in Android. This is a handy feature when you just want a
simple means of interacting with the user interface.
Although specific to Service implementations, which should always be threaded, the
IntentService provides automatic single-threading for simple implementations, saving tons of code
the Service developer.

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