常用的java函数（十）随机函数

*
 * @author talent_marquis<��˺��>
 * Email: [e-mail]
 * Copyright (C) 2007 talent_marquis<��˺��>
 * All rights reserved.
 */
package com.dextrys.trilogy.util;

import java.util.Arrays;

import org.eclipse.swt.graphics.RGB;

public class RandomUtil
{

    /**
     * @param args
     */
    public static void main( String[] args )
    {
        //System.out.println( getRandomNormalString( 8 ) );
        int[] test = getRandomIntWithoutReduplicate( 0, 40, 39 );
        Arrays.sort( test );
        for( int i : test )
        {
            System.out.println( i );
        }
    }

    /**
     * get a integer array filled with random integer without reduplicate [min, max)
     * @param min    the minimum value
     * @param max the maximum value
     * @param size the capacity of the array
     * @return a integer array filled with random integer without redupulicate
     */
    public static int[] getRandomIntWithoutReduplicate( int min, int max, int size )
    {
        int[] result = new int[size];
        
        int arraySize = max - min;
        int[] intArray = new int[arraySize];
        // init intArray
        for( int i = 0 ; i < intArray.length ; i++ )
        {
            intArray[i] = i + min;
        }
        // get randome interger without reduplicate
        for( int i = 0 ; i < size ; i++ )
        {
            int c = getRandomInt( min, max - i );
            int index = c - min;
            swap( intArray, index, arraySize - 1 - i );
            result[i] = intArray[ arraySize - 1 - i ];
        }
                
        return result;
    }
    
    private static void swap( int[] array, int x, int y )
    {
        int temp = array[x];
        array[x] = array[y];
        array[y] = temp;
    }
    
    /**
     * get a random Integer with the range [min, max)
     * @param min the minimum value
     * @param max the maximum value
     * @return the random Integer value
     */
    public static int getRandomInt( int min, int max )
    {
        // include min, exclude max
        int result = min + new Double( Math.random() * ( max - min ) ).intValue();

        return result;
    }

    /**
     * get a random double with the range [min, max)
     * @param min the minimum value
     * @param max the maximum value
     * @return the random double value
     */
    public static double getRandomDouble( double min, double max )
    {
        // include min, exclude max
        double result = min + ( Math.random() * ( max - min ) );
        return result;
    }

    /**
     * 
     * @return a random char with the range ASCII 33(!) to ASCII 126(~)
     */
    public static char getRandomChar()
    {
        // from ASCII code 33 to ASCII code 126
        int firstChar = 33; // "!"
        int lastChar = 126; // "~"
        char result = ( char ) ( getRandomInt( firstChar, lastChar + 1 ) );
        return result;
    }
    
    /**
     * 
     * @return a random rgb color
     */
    public static RGB getRandomRGB()
    {
        int red = getRandomInt(0,256);
        int green = getRandomInt(0,256);
        int blue = getRandomInt(0,256);
        
        return new RGB( red, green, blue );
    }
    
    /**
     * 
     * @return a random char with the range [0-9],[a-z],[A-Z]
     */
    public static char getRandomNormalChar()
    {
        // include 0-9,a-z,A-Z
        int number = getRandomInt( 0, 62 );
        int zeroChar = 48;
        int nineChar = 57;
        int aChar = 97;
        int zChar = 122;
        int AChar = 65;
        int ZChar = 90;
        
        char result;
        
        if( number < 10 )
        {
            result =  ( char ) ( getRandomInt( zeroChar, nineChar + 1 ) );
            return result;

        }
        else if( number >= 10 && number < 36 )
        {
            result = ( char ) ( getRandomInt( AChar, ZChar + 1 ) );
            return result;
        }
        else if( number >= 36 && number < 62 )
        {
            result =  ( char ) ( getRandomInt( aChar, zChar + 1 ) );
            return result;
        }
        else
        {
            return 0;
        }
    }

    /**
     * 
     * @param length the length of the String
     * @return a String filled with random char
     */
    public static String getRandomString( int length )
    {
        // include ASCII code from 33 to 126
        StringBuffer result = new StringBuffer();
        for( int i = 0; i < length; i++ )
        {
            result.append( getRandomChar() );
        }
        return result.toString();
    }
    
    /**
     *     
     * @param length the length of the String
     * @return a String filled with normal random char
     */
    public static String getRandomNormalString( int length )
    {
        // include 0-9,a-z,A-Z
        StringBuffer result = new StringBuffer();
        for( int i = 0; i < length; i++)
        {
            result.append( getRandomNormalChar() );
        }
        return result.toString();
    }
}