添加独特的随机数的整数数组

问题描述

我已经为这，我想，以填补200号整数一个ArrayList。每个数字都可以是一个范围内0和1023之间。

I've created an ArrayList for integers which I would like to fill with 200 numbers. Each number can be within a range between 0 and 1023.

所以我写这code：

Random rand = new Random();
ArrayList<Integer> values = new ArrayList<Integer>();

int START_AMOUNT = 200;

for(int i = 0; i < START_AMOUNT; 

  values.add(rand.nextInt(1024));      

}

如您所看到的，for循环将增加200随机数的价值的ArrayList，从0到1023。现在我的问题是，我想向数组只有唯一的数字。我怎么能告诉Random类不产生已经是存在的ArrayList中？

As You might see, the for-loop will add 200 random numbers to the "values" ArrayList, from 0 to 1023. Now my problem is that I want the Array to have only unique numbers. How can I tell the Random class not to generate any numbers that already are existent in the ArrayList?

推荐答案

我会做的是建立由1,2,3，...，1023由1023整数的数组。然后你得洗它，你只需要200第一项：

What I'd do is creating an array of 1023 int composed by 1,2,3,...,1023. Then you shuffle it, and you take only the 200 first terms :

List<Integer> ints = new ArrayList<Integer>();
for(int i = 1; i <= 1023; i++)
{
    ints.add(i);
}

Collections.shuffle(ints);

：由建议编辑@波西米亚♦

List<Integer> result = ints.subList(0,200);

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