int[] array = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
        int result = 0;
        Random random = new Random();
        for (int i = 0, len = 8, index = 0; i < 4; i++) {
            index = random.nextInt(len);
            result = result * 10 + array[index];
            array[index] = array[len-- + 1];
        }
        System.out.println("result -> " + result);

------解决方案--------------------
我这个测试过的啦，没问题的

package com.gzsoft.zoom;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Random;
import java.util.Set;

public class TestSIWEISHU {

	
	public static void main(String[] args) {
		Random rand=new Random();
	 List set=new ArrayList();
	 set.add(0);
	 for(int i=0;i<10;i++){
		 set.add(new Integer(i));
	 }
	  
	
	 int beishu=1;
	 int result=0;
	  
	 for(int i=0;i<4;i++){
		 int ranNum=rand.nextInt(9-i);
		 Integer in=(Integer) set.get(ranNum);
		 set.remove(in);
		 result+=in*beishu;
		 beishu=beishu*10;
		 if(i==2){
			 set.remove(new Integer(0));
		 }
	 }
	System.out.print(result);
	
	}

}