1. Strings & Arrays
CST200 – Week 1
Instructor: Andreea Molnar

2. Outline
• Strings
• Arrays

3. 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.

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

5. Escape Sequences
Escape sequence Meaning
b backspace
t tab
n newline
r return
’’ double quote
’ single quote
backslash

6. Escape Sequences
String firstName = "Mary";
String lastName = "Smith";
System.out.println(firstName + "t" + lastName);
Mary Smith
System.out.println(firstName + "n" + lastName);
Mary
Smith
System.out.println(firstName + """ + lastName);
Mary"Smith
System.out.println(firstName + "" + lastName);
MarySmith

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 counted
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 S T 2 0 0
0 1 2 3 4 5 6
index

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

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

13. Strings - Methods
String indexOf (String str)
returns the index of the first occurrence of str
if multiple occurrences returns just the first one
String s = “CST 200”;
C S T 2 0 0
0 1 2 3 4 5 6
System.out.println(s.indexOf(“T”));
//will print 2

14. String Methods
String substring(int beginIndex, int endIndex)
returns a substring that begins at the
beginIndex and ends at the endIndex -1
String str = “Arizona State University”;
str.substring (3, 5); //substring that begins at the index 3
(z) and ends at the 5-1 (o)  zo

15. Arrays
Array is a container that holds a fixed
number of values.
int[] array = {10, 20, 30, 50};
10 20 30 50
0 1 2 3
index

16. 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
System.out.println(array[3]);//will print 50

17. Summary
• The first character of a String starts at
position 0
• The first element of an array starts at
the position 0