我试图在Java中反转一个int数组。

此方法不反转数组。

for(int i = 0; i < validData.length; i++)
{
    int temp = validData[i];
    validData[i] = validData[validData.length - i - 1];
    validData[validData.length - i - 1] = temp;
}

有什么问题吗?


当前回答

以下是精简版:

我的解决方案创建了一个反转的新数组 每次迭代i时,for循环都会插入最后一个索引[array]。长度- 1]到当前索引[i] 然后通过减去当前迭代数组[(array. array.)]继续相同的过程。长度- 1)- i]从最后一个索引和插入元素到反向数组的下一个索引!

private static void reverse(int[] array) {
    int[] reversed = new int[array.length];

    for (int i = 0; i < array.length; i++) {
        reversed[i] = array[(array.length - 1) - i];
    }
    System.out.println(Arrays.toString(reversed));
}

其他回答

public void display(){
  String x[]=new String [5];
  for(int i = 4 ; i > = 0 ; i-- ){//runs backwards

    //i is the nums running backwards therefore its printing from       
    //highest element to the lowest(ie the back of the array to the front) as i decrements

    System.out.println(x[i]);
  }
}

它有两个解

Loop Recursion public class _1_ReverseArray { public static void main(String[] args) { int array[] = {2, 3, 1, 4, 9}; //reverseArray(array, 0, array.length - 1); reverseArrayWhileLoop(array, 0, array.length - 1); printArray(array); } private static void printArray(int[] array) { for (int a : array) { System.out.println(a); } } private static void reverseArray(int[] array, int start, int end) { if (start > end) { return; } else { int temp; temp = array[start]; array[start] = array[end]; array[end] = temp; reverseArray(array, start + 1, end - 1); } } private static void reverseArrayWhileLoop(int[] array, int start, int end) { while (start < end) { int temp; temp = array[start]; array[start] = array[end]; array[end] = temp; start++; end--; } } }

以下是我想到的:

// solution 1 - boiler plated 
Integer[] original = {100, 200, 300, 400};
Integer[] reverse = new Integer[original.length];

int lastIdx = original.length -1;
int startIdx = 0;

for (int endIdx = lastIdx; endIdx >= 0; endIdx--, startIdx++)
   reverse[startIdx] = original[endIdx];

System.out.printf("reverse form: %s", Arrays.toString(reverse));

// solution 2 - abstracted 
// convert to list then use Collections static reverse()
List<Integer> l = Arrays.asList(original);
Collections.reverse(l);
System.out.printf("reverse form: %s", l);
 public static int[] reverse(int[] array) {

    int j = array.length-1;
    // swap the values at the left and right indices //////
        for(int i=0; i<=j; i++)
        {
             int temp = array[i];
                array[i] = array[j];
                array[j] = temp;
           j--;
        }

         return array;
    }

      public static void main(String []args){
        int[] data = {1,2,3,4,5,6,7,8,9};
        reverse(data);

    }

上面有一些很棒的答案,但我是这样做的:

public static int[] test(int[] arr) {

    int[] output = arr.clone();
    for (int i = arr.length - 1; i > -1; i--) {
        output[i] = arr[arr.length - i - 1];
    }
    return output;
}