simple java(八)---for loop(1)

for loop

它的結構係:for ( int number = 2; number <= 100; number += 2 ) 例一.

import javax.swing.JOptionPane;

public class Sum {

public static void main( String args[] ) {

int sum = 0;

for ( int number = 2; number <= 100; number += 2 )

sum += number;

JOptionPane.showMessageDialog( null, "The sum is " + sum,"Sum Even Integers from 2 to 100",JOptionPane.INFORMATION_MESSAGE );

System.exit( 0 ); }}

執行結果:

The sum is 2250

等本人解釋一下以上程式,首先電腦先執行int number = 2,睇下2合乎 <= 100,如果合乎就執行sum += number

***********************

Nested Loop

例二.

public class NestedLoop1 {

public static void main( String args[] ) {

for(int i=1; i<=7;i++) {

for ( int j = 1; j <= 5; j++ ) {

System.out.print( "*" );

}

System.out.print("\n");

}}}

執行結果:

*****

*****

*****

*****

*****

*****

* * * * *

************************

例三.

public class NestedLoop2 {

public static void main( String args[] ) {

for ( int i = 1; i <= 7; i++ ) {

for ( int j = 1; j <= i; j++ ) {

System.out.print( "*" );}

System.out.print( "\n" );

}}}

執行結果:

*

**

***

****

*****

******

*******