Find missing in second array

//Find missing in second array

import java.io.*;
import java.util.*;

class Solution {
    ArrayList<Integer> findMissing(int a[], int b[], int n, int m) {
        ArrayList<Integer> ans = new ArrayList<>();
        Map<Integer, Integer> map = new HashMap<>();
        
        for(int elb : b) {
            map.put(elb, 1);
        }
        
        for(int ela : a) {
            if(!map.containsKey(ela)) {
                ans.add(ela);
            }
        }
        
        return ans;
    }
}

class Array {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int testcases = Integer.parseInt(br.readLine());

        while(testcases-- > 0) {
            String line = br.readLine();
            String[] q = line.trim().split("\\s+");
            int n =Integer.parseInt(q[0]);
            int m =Integer.parseInt(q[1]);
            String line1 = br.readLine();
            String[] a1 = line1.trim().split("\\s+");
            int a[] = new int[n];

            for(int i = 0; i < n; i++) {
                a[i] = Integer.parseInt(a1[i]);
            }

            String line2 = br.readLine();
            String[] a2 = line2.trim().split("\\s+");
            int b[] = new int[m];

            for(int i = 0; i < m; i++) {
                b[i] = Integer.parseInt(a2[i]);
            }

            Solution ob = new Solution();
            ArrayList<Integer> ans=ob.findMissing(a,b,n,m);

            for(int i = 0; i < ans.size(); i++) {
                System.out.print(ans.get(i)+" ");
            }
            System.out.println();
        }
    }