Cacher is the code snippet organizer for pro developers

public class Solution {
    public int[] nextGreaterElement(int[] findNums, int[] nums) {
        
        HashMap<Integer, Integer> map = new HashMap<>();        // *** 
        Stack<Integer> stack = new Stack<>();                   // ****
        
        for(int num : nums){
        
            while(!stack.isEmpty() && stack.peek() < num){    // stack.peek()
                map.put(stack.pop(), num);                    // ** map.put(x), stack.pop()
            }
            stack.push(num);                                    // stack.push(x)
        }
        
        for(int i = 0; i< findNums.length ; i++){
            if (map.get(findNums[i]) != null){            // map.get(x) != null  // if key doesn't exist
                findNums[i] = map.get(findNums[i]);
            }else {
                findNums[i] = -1;
            }
        }
        
        return findNums;
        
    }
}