This document provides an introduction to Java concepts like strings and arrays. It outlines that strings are sequences of characters that have methods like length() and charAt() which return the string length and character at a given index. Arrays are containers that hold a fixed number of values, with the first element starting at position 0. Basic concepts covered include expressions and algorithms.

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