The Java Boutique: Java Tutorial: Java by Example: Operators and Methods

Tutorials : Java by Example : Section 2 :

Section Two Contents

Operators and Methods

Introducting the Operators - Con't

The comparison operators and the logical operators are as follows:

Operator Meaning Example

== equal if(a==b)c=d

!= not equal if(a!=b)c=0

< less than if(a<b)c=d

<= less or equal than if(a<=b)c=d

> greater than if(a>b)c=d

>= greater or equal than if(a>=b)c=d

! not (logical) if(!a)c=d

&& and (logical) if(a==1&&b==2)c=d

|| or (logical) if(a<10||b==0)c=d

Provided that "a" is a boolean variable, you can write: if(a)b=c instead of if(a==true)b=c, and if(!a)b=c instead of if(a==false)b=c, this is shorter and quite common. Remember that the operators * and / go before + and -, so you will often have to put combined expression inside brackets.

The following example demonstrates some of the basic operators, both comparison and boolean (see the sourcecode to understand what is going on here):

//Sourcecode

import java.awt.*; import java.applet.*; public class Project5E extends Applet { public void paint(Graphics g) { int a=3; int b=3; int c=2; int d=5; boolean x=false; g.setFont(new Font("Helvetica",Font.PLAIN,18)); if(a==b)x=true; g.drawString("x = "+x, 110,30); if(a==c)x=true; else x=false; g.drawString("x = "+x, 110,50); if(a>c)x=true; else x=false; g.drawString("x = "+x, 110,70); if(b>=c)x=true; else x=false; g.drawString("x = "+x, 110,90); if(a==b&&c>d)x=true; else x=false; g.drawString("x = "+x, 110,110); if(a==b||c>d)x=true; else x=false; g.drawString("x = "+x, 110,130); } }

Applet Index
(sorted alphabetically)
A B C D E F G H I J K
L M N O P Q R S T U
V W X Y Z #s

The Java Source
(applets w/source code)
A B C D E F G H I J K
L M N O P Q R S T U
V W X Y Z

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