java - How to reverse an ArrayList without the reverse method? -

hello trying reverse arraylist without reverse method. wanted make work without method. can't seem right. have far:

for (int x = nums.size()-1; x>=0; x--)     {          for(int z =0; z<nums.size();z++)         {             nums.set(z, x);          }     } 

this output: run: 0 1 2 3

1 1 1 1 build successful (total time: 0 seconds)

you can ascend bottom & simultaneously descend top (size() - 1) swapping elements, , stop when meet in middle.

int = 0; int j = nums.size()-1; while (i < j) {     int temp = nums.get(i);     nums.set( i, nums.get(j));     nums.set( j, temp);     i++; j--; }