simple java(十)---methods(functions)(1)

methods

其實好多程式會成日重複用,加上為了方便人地好多程已經寫好了..只要CALL它們出來就可以了...

例一.

import javax.swing.*;

public class SquareRoot {

public static void main( String args[] ) {

String numString;

double number;

double answer;

numString = JOptionPane.showInputDialog("Enter a double number" );

number = Double.parseDouble( numString );

answer = Math.sqrt( number );

JOptionPane.showMessageDialog( null,"The square root of " + number + " is " + answer);

System.exit( 0 );}}

執行結果:

Enter a double number

20.5

The square root of 20.5 is4.52769256

等本人試下解釋以上程式.首先輸入一個double number,而個答案一早放左係Math.sqrt( )到..call 番佢出黎就可以...

例二.

import javax.swing.JOptionPane;

public class Hello {

public static void main(String args[]) {

int value;

String output = "";

for (int counter = 1; counter <= 20; counter++) {

value = 1 + (int) (Math.random() * 6);

output += value + " ";

if (counter % 5 == 0)

output += "\n";}

JOptionPane.showMessageDialog(null, output,"20 Random Numbers from 1 to 6",JOptionPane.INFORMATION_MESSAGE);

System.exit(0); }}

例三.

public class CalSquare {

public static void main(String args[]) {

int result;

System.out.println("Value\tResult");

for(int i=1; i<=10; i++)

{

result = square(i);

System.out.println(i+"\t"+result);}

}

public static int square(int value){

int retvalue;

retvalue = value * value;

return retvalue;}}

執行結果:

value result

1 1

2 4

3 9

4 16

5 25

6 36

7 4 9

8 64

9 81

10 100