我需要随机洗牌以下数组:

int[] solutionArray = {1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1};

有什么函数可以做到吗?


当前回答

下面是使用集合的完整解决方案。洗牌的方法:

public static void shuffleArray(int[] array) {
  List<Integer> list = new ArrayList<>();
  for (int i : array) {
    list.add(i);
  }

  Collections.shuffle(list);

  for (int i = 0; i < list.size(); i++) {
    array[i] = list.get(i);
  }    
}

请注意,由于Java无法在int[]和Integer[]之间平滑转换(因此int[]和List<Integer>),它受到了影响。

其他回答

下面是一个有效的Fisher-Yates shuffle数组函数:

private static void shuffleArray(int[] array)
{
    int index;
    Random random = new Random();
    for (int i = array.length - 1; i > 0; i--)
    {
        index = random.nextInt(i + 1);
        if (index != i)
        {
            array[index] ^= array[i];
            array[i] ^= array[index];
            array[index] ^= array[i];
        }
    }
}

or

private static void shuffleArray(int[] array)
{
    int index, temp;
    Random random = new Random();
    for (int i = array.length - 1; i > 0; i--)
    {
        index = random.nextInt(i + 1);
        temp = array[index];
        array[index] = array[i];
        array[i] = temp;
    }
}

使用集合来洗牌一个基本类型数组有点过分……

你自己实现这个函数很简单,比如使用Fisher-Yates shuffle:

import java.util.*;
import java.util.concurrent.ThreadLocalRandom;

class Test
{
  public static void main(String args[])
  {
    int[] solutionArray = { 1, 2, 3, 4, 5, 6, 16, 15, 14, 13, 12, 11 };

    shuffleArray(solutionArray);
    for (int i = 0; i < solutionArray.length; i++)
    {
      System.out.print(solutionArray[i] + " ");
    }
    System.out.println();
  }

  // Implementing Fisher–Yates shuffle
  static void shuffleArray(int[] ar)
  {
    // If running on Java 6 or older, use `new Random()` on RHS here
    Random rnd = ThreadLocalRandom.current();
    for (int i = ar.length - 1; i > 0; i--)
    {
      int index = rnd.nextInt(i + 1);
      // Simple swap
      int a = ar[index];
      ar[index] = ar[i];
      ar[i] = a;
    }
  }
}

你应该使用Collections.shuffle()。但是,不能直接操作原始类型数组,因此需要创建包装器类。

试试这个。

public static void shuffle(int[] array) {
    Collections.shuffle(new AbstractList<Integer>() {
        @Override public Integer get(int index) { return array[index]; }
        @Override public int size() { return array.length; }
        @Override public Integer set(int index, Integer element) {
            int result = array[index];
            array[index] = element;
            return result;
        }
    });
}

And

int[] solutionArray = {1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1};
shuffle(solutionArray);
System.out.println(Arrays.toString(solutionArray));

输出:

[3, 3, 4, 1, 6, 2, 2, 1, 5, 6, 5, 4]

Groovy的一个简单解决方案:

solutionArray.sort{ new Random().nextInt() }

这将对数组列表中的所有元素进行随机排序,存档所有元素洗牌的预期结果。

最简单的解决方案,这种随机洗牌数组。

String location[] = {"delhi","banglore","mathura","lucknow","chandigarh","mumbai"};
int index;
String temp;
Random random = new Random();
for(int i=1;i<location.length;i++)
{
    index = random.nextInt(i+1);
    temp = location[index];
    location[index] = location[i];
    location[i] = temp;
    System.out.println("Location Based On Random Values :"+location[i]);
}