生成8位随机不重复的数字编号

package com.jjinfo.common.util; 

import java.util.Arrays; 

import java.util.Random; 

   

/**

 *

 */ 

public class RandomNumberGenerator { 

   

    /**

     * 这是典型的随机洗牌算法。

     * 流程是从备选数组中选择一个放入目标数组中，将选取的数组从备选数组移除（放至最后，并缩小选择区域）

     * 算法时间复杂度O(n)

     * @return 随机8为不重复数组

     */ 

    public static String generateNumber() { 

        String no=""; 

        //初始化备选数组 

        int[] defaultNums = new int[10]; 

        for (int i = 0; i < defaultNums.length; i++) { 

            defaultNums[i] = i; 

        } 

   

        Random random = new Random(); 

        int[] nums = new int[LENGTH]; 

        //默认数组中可以选择的部分长度 

        int canBeUsed = 10; 

        //填充目标数组 

        for (int i = 0; i < nums.length; i++) { 

            //将随机选取的数字存入目标数组 

            int index = random.nextInt(canBeUsed); 

            nums[i] = defaultNums[index]; 

            //将已用过的数字扔到备选数组最后，并减小可选区域 

            swap(index, canBeUsed - 1, defaultNums); 

            canBeUsed--; 

        } 

        if (nums.length>0) { 

            for (int i = 0; i < nums.length; i++) { 

                no+=nums[i]; 

            } 

        } 

   

        return no; 

    } 

    private static final int LENGTH = 8; 

   

    private static void swap(int i, int j, int[] nums) { 

        int temp = nums[i]; 

        nums[i] = nums[j]; 

        nums[j] = temp; 

    } 

       

    public static String generateNumber2() { 

        String no=""; 

        int num[]=new int[8]; 

        int c=0; 

        for (int i = 0; i < 8; i++) { 

            num[i] = new Random().nextInt(10); 

            c = num[i]; 

            for (int j = 0; j < i; j++) { 

                if (num[j] == c) { 

                    i--; 

                    break; 

                } 

            } 

        } 

        if (num.length>0) { 

            for (int i = 0; i < num.length; i++) { 

                no+=num[i]; 

            } 

        } 

        return no; 

    } 

   

    public static void main(String[] args) { 

        for (int i = 0; i < 10; i++) { 

//            System.out.println(generateNumber()); 

            System.out.println(generateNumber2()); 

        } 

    } 

}