java - 如何找到一个数组在另一个数组中的出现？并返回第一个数组的索引

Question

这是我正在尝试完成但不知道如何前进的算法，

public int findArray(int[] array, int[] subArray) {
    for (int i = 0; i < array.length; i++) {
        for (int j = 0; i < subArray.length; j++) {
            if (array[i] == subarray[j]) {//not sure if this is how to start 

            }
        }//will want to compare all element in subarray to Array
    }
    return 0;
}

我想要的结果如下

//[4,9,3,7,8] and [3,7] should return 2.
//[7,8,9] and [8,9,10] should return -1

//[4,9,3,7,8,3,7,1] and [3,7]should return 5

我的理解是我将子数组作为一个整体，并尝试在数组中找到它匹配的位置，但不知道该怎么做

Answer 1

一种简单的方法:

// 1) Convert array to String, for eg. [1,2,3,4] => "1234". 
// 2) Use Strings substring/lastIndexOf to find the correct index. 

private static int findSubarrayPosition(int[] array, int[] subarray) {
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < array.length; i++) {
          sb.append(array[i]);
      }
      String string = sb.toString();

      sb = new StringBuilder();
      for (int i = 0; i < subarray.length; i++) {
          sb.append(subarray[i]);
      }
      String subString = sb.toString();

      return string.lastIndexOf(subString);
}