Why I use my way in my computer is success but fail in leetcode test?
When I outprint my answer is correct in this way.
Even just use nums1 = nums3; and outprint it also is correct.

import java.util.*;
class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        ArrayList<Integer> _nums1 = new ArrayList<>();
        ArrayList<Integer> _nums2 = new ArrayList<>();
        for(int i=0;i<nums1.length;i++){
            if(nums1[i]!=0){
                _nums1.add(nums1[i]);
            }
        }
        for(int i=0;i<nums2.length;i++){
            if(nums2[i]!=0){
                _nums2.add(nums2[i]);
            }
        }

        ArrayList<Integer> result = new ArrayList<>();
        result.addAll(_nums1);
        result.addAll(_nums2);
        Collections.sort(result);

        int x=_nums1.size();
        int j=0;
        int[] nums3 = new int[_nums1.size()+_nums2.size()];
        for(int i=0; i<_nums1.size(); i++){
            nums3[i] = _nums1.get(i);
        }
        for(int i=x; i<_nums1.size()+_nums2.size(); i++){
            nums3[i] = _nums2.get(j);
            j++;
        }
        Arrays.sort(nums3);
        nums1 = new int[_nums1.size()+_nums2.size()];
        /*nums1 = nums3*/
        for(int i=0;i<nums1.length;i++){
            nums1[i] = nums3[i];
        }
    }
}