Java質問スレで見てたけどこんな感じ？

import java.io.*;
import java.util.*;

public class RandomStack{
public static void main(String[] args){
Random rdm = new Random();
int[] stacks = new int[31];
for(int i=0;i<31;i++){
stacks[i] = i;
//System.out.println(stacks[i]);
}
int trda;
int trdb;
int tmp;
for(int i=0;i<1000;i++){
trda = rdm.nextInt(31);
trdb = rdm.nextInt(31);
tmp = stacks[trda];
stacks[trda] = stacks[trdb];
stacks[trdb] = tmp;
}
for(int i=0;i<5;i++){
System.out.println("["+i+"]:"+stacks[i]);
}
}
}