1. Introduction to
Java
CST200 – Week 1: Introduction to Java
Instructor: Andreea Molnar

2. Outline
• Aims
• Basic Concepts
• Strings
• Arrays

3. Aim
• The aim of this presentation is to
emphasis on some of the material
covered by the pluralsigh videos.

4. Basic Concepts
• Expression: see more about them here:
http://www.d.umn.edu/~gshute/java/stat
ements.html
• Algorithm: see a definition here:
http://en.wikipedia.org/wiki/Algorithm

5. Strings and Arrays
The first letter of a String is at the
position 0 and the first value of an array
is at the position 0.

6. Strings
Any sequence of characters, for example:
String s = “Arizona”;
String s = “1457 Mesa”;
String s = “@u”;

7. Strings - Methods
You can find all the String methods at:
http://docs.oracle.com/javase/7/docs/api/j
ava/lang/String.html

8. Strings - Methods
public int length() – returns the length of
the string
String s = “CST 200”;
s.length() – will return 7 as there are 7
characters in the string

9. Strings - Methods
public int length() – returns the length of
the string
String s = “CST 200”;
s.length() – will return 7 as there are 7
characters in the string (space is count as
a separate character)

10. Strings - Methods
public char charAt(int index)– returns the
character value at the specified index
String s = “CST 200”;
C
T
0
index
S
1
2
2
3
0
0
4
5
6

11. Strings - Methods
public char charAt(int index)– returns the
character value at the specified index
String s = “CST 200”;
C
S
T
0
1
2
2
3
0
0
4
5
6
The first character of a String is at the
position 0!!!

12. Strings - Methods
String s = “CST 200”;
C
S
T
0
1
2
2
3
0
0
4
5
6
System.out.println(s.charAt(0));//will print C
System.out.println(s.charAt(6));//will print 0

13. Strings - Methods
public int indexOf(String str) - returns the
index within this string of the first
occurrence of the specified substring
String s = “CST 200”;
C
S
T
0
1
2
2
3
0
0
4
5
6
System.out.println(s.indexOf(“T”));
//will print 3

14. Arrays
Array is a container that holds a fixed
number of values.
int[] array = {10, 20, 30, 50};
10
20
30
50
0
2
3
4
index

15. Arrays
int[] array = {10, 20, 30, 50};
10
20
30
50
0
1
2
3
To print the values of this array:
System.out.println(array[0]);//will print 10
System.out.println(array[1]);//will print 20
System.out.println(array[2]);//will print 30

16. Summary
• Expression definition
• Algorithm definition
• The first character of an array starts at
position 0
• The first element of an array starts at
the position 0