Tutorial 1 - Learning About Basic Widgets In Android

1. Android.Widgets
Tutorial 1 : Empowering Android Widgets
By: Mr.PrajyotMainkar
MS Software Systems( BITS-Pilani)
BE(Hons.) Computer Engineering , PMP( IIT Delhi)
S

2. TextView – The Andro-Label
The simplest widget is the label, referred to in Android as a TextView .
Typically, these are used like labels in Android UI
Create a new android project with following contents in main.xml and run this project
on emulator
<?xml version="1.0" encoding="utf-8"?>
<TextViewxmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="This is sample demo of TextView"
/>

3. TextView – The Andro-Label
The following output is obtained when you run the code via emulator.

4. Images – Fleeting with images
Android has two widgets to help embed images in your activities: ImageViewand
ImageButton.
As the names suggest, they are image-based analogues to TextView and
Button , respectively.
<?xml version="1.0" encoding="utf-8"?>
<ImageViewxmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/icon"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:adjustViewBounds="true"
android:src="@drawable/logo"
/>
Note that, android:src takes path of image from the drawable folder(@ is the
reference), so drag „n drop /paste any logo.png image to drawable folder.

5. Images – Fleeting with images
The following output is obtained when you run the code via emulator.

6. EditText– Learning EditText
EditText is a thin veneer over TextView that configures itself to be editable. In the java
file (Src folder) import the file “import android.widget.EditText;”. Find the xml code
below
<?xml version="1.0" encoding="utf-8"?>
<EditTextxmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/editfield"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:singleLine="false"
/>

7. EditText – Learning EditText
package com.EditTextDemo;
import android.app.Activity;
import android.os.Bundle;
import android.widget.EditText;
public class EditTextDemoActivity extends Activity {
/** Called when the activity is first created. */
@Override
EditText E;
public void onCreate(BundlesavedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
E.setText("This is sample edit text demo");
}
}

8. CheckBox– Lets *Check*
•isChecked(): Determines if the check box has been checked.
•setChecked(): Forces the check box into a checked or unchecked
•state.
•toggle(): Toggles the check box as if the user checked it.
<?xml version="1.0" encoding="utf-8"?>
<CheckBoxxmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/checkbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="This checkbox is unchecked" />

9. CheckBox – Lets *Check*
package com.CheckBoxDemo;
import android.app.Activity;
import android.os.Bundle;
import android.widget.CheckBox;
import android.widget.CompoundButton;
public class CheckBoxDemoActivity extends Activity implements CompoundButton.OnCheckedChangeListener {
CheckBox checkbox;
public void onCreate(BundlesavedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
checkbox=(CheckBox)findViewById(R.id.checkbox);
checkbox.setOnCheckedChangeListener(this);
}
public void onCheckedChanged(CompoundButtonbuttonView,
booleanisChecked) {
if (isChecked) {
checkbox.setText("This checkbox is: checked");
}
else {
checkbox.setText("This checkbox is: unchecked");
}
}
}

10. CheckBox – Lets *Check*
The following output is obtained when you run the code via emulator.

11. RadioButton – Tune Up
•check(): Checks a specific radio button via its ID
•clearCheck(): Clears all radio buttons, so none in the group are checked.
•getCheckedRadioButtonId(): Gets the ID of the currently checked radio button (or -1 if
none are checked).
Most times RadioButton widgets are placed inside a RadioGroup . The
RadioGroup indicates a set of radio buttons whose state is tied, meaning only one
button
in that group can be selected at any time. If you assign an android:id to your
RadioGroup in your XML layout, you can access the group from your Java code and

12. RadioButton – Tune Up
•The XML Code is below. Make no changes to Java File :
<?xml version="1.0" encoding="utf-8"?>
<RadioGroup
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<RadioButton android:id="@+id/radio1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Goa" />
<RadioButton android:id="@+id/radio2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Maharashtra" />
<RadioButton android:id="@+id/radio3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Kerala" />
</RadioGroup>

13. Thank you..
GET IN TOUCH– Tune Up
RadioButton
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