Tutorials : Java by Example : Section 2 :

Operators and Methods

Introducting the Operators - Con't

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); } }

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