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

我在权衡这个非常流行的问题,因为没有人写过一个shuffle-copy版本。样式大量借鉴了Arrays.java,因为现在谁没有掠夺Java技术呢?包括泛型和int实现。

   /**
    * Shuffles elements from {@code original} into a newly created array.
    *
    * @param original the original array
    * @return the new, shuffled array
    * @throws NullPointerException if {@code original == null}
    */
   @SuppressWarnings("unchecked")
   public static <T> T[] shuffledCopy(T[] original) {
      int originalLength = original.length; // For exception priority compatibility.
      Random random = new Random();
      T[] result = (T[]) Array.newInstance(original.getClass().getComponentType(), originalLength);

      for (int i = 0; i < originalLength; i++) {
         int j = random.nextInt(i+1);
         result[i] = result[j];
         result[j] = original[i];
      }

      return result;
   }


   /**
    * Shuffles elements from {@code original} into a newly created array.
    *
    * @param original the original array
    * @return the new, shuffled array
    * @throws NullPointerException if {@code original == null}
    */
   public static int[] shuffledCopy(int[] original) {
      int originalLength = original.length;
      Random random = new Random();
      int[] result = new int[originalLength];

      for (int i = 0; i < originalLength; i++) {
         int j = random.nextInt(i+1);
         result[i] = result[j];
         result[j] = original[i];
      }

      return result;
   }

其他回答

还有另一种方法,还没有发布

//that way, send many object types diferentes
public anotherWayToReciveParameter(Object... objects)
{
    //ready with array
    final int length =objects.length;
    System.out.println(length);
    //for ready same list
    Arrays.asList(objects);
}

这种方法更简单,取决于上下文

看看Collections类,特别是shuffle(…)。

这是另一种洗牌的方法

public List<Integer> shuffleArray(List<Integer> a) {
    List<Integer> b = new ArrayList<Integer>();
    while (a.size() != 0) {
        int arrayIndex = (int) (Math.random() * (a.size()));
        b.add(a.get(arrayIndex));
        a.remove(a.get(arrayIndex));
    }
    return b;
}

从原始列表中选择一个随机数,并将其保存在另一个列表中。然后从原始列表中删除该数字。原始列表的大小将继续减小1,直到所有元素都移动到新列表中。

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。

public class ShuffleArray {
public static void shuffleArray(int[] a) {
    int n = a.length;
    Random random = new Random();
    random.nextInt();
    for (int i = 0; i < n; i++) {
        int change = i + random.nextInt(n - i);
        swap(a, i, change);
    }
}

private static void swap(int[] a, int i, int change) {
    int helper = a[i];
    a[i] = a[change];
    a[change] = helper;
}

public static void main(String[] args) {
    int[] a = new int[] { 1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1 };
    shuffleArray(a);
    for (int i : a) {
        System.out.println(i);
    }
}
}