假如我有一个数组:
  ArrayList<Integer> mArrayList = new ArrayList<Integer>();
  mArrayList.add(0);
  mArrayList.add(1);
  mArrayList.add(2);
  mArrayList.add(3);
  我需要从中随机抽取2个数  不能重复抽取,我会用这个方法
  public void getValue(ArrayList<Integer> mArrayList){
  Random mRandom = new Random();
  int a = mRandom.nextInt(mArrayList.size());
  int value = mArrayList.get(a);
  System.out.println(value + "");
  mArrayList.remove(a);
  }
  原理是每抽取一次删除已经抽取出来的值,这样获取到的值不会重复了
  完整代码:
package com.xiaoqiu.test;
import java.util.ArrayList;
import java.util.Random;
public class Test {
public static void main(String[] args) {
ArrayList<Integer> mArrayList = new ArrayList<Integer>();
mArrayList.add(0);
mArrayList.add(1);
mArrayList.add(2);
mArrayList.add(3);
Test mTest = new Test();
mTest.getValue(mArrayList);
mTest.getValue(mArrayList);
}
public void getValue(ArrayList<Integer> mArrayList){
Random mRandom = new Random();
int a = mRandom.nextInt(mArrayList.size());
int value = mArrayList.get(a);
System.out.println(value + "");
mArrayList.remove(a);
}
}
  测试结果:
  3
  2
  3
  0
  2
  3