array to ArrayList

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;

public class Solution {
	public String solution(String[] participant, String[] completion) {
        
		String answer = "";
        
        ArrayList<String> arr = new ArrayList<String>();
        ArrayList<String> arr1 = new ArrayList<String>();
        
        Collections.addAll(arr, participant);
        Collections.addAll(arr1, completion);
        
        Iterator<String> iter = arr.iterator();
        Iterator<String> iter1 = arr1.iterator();

        
        while (iter.hasNext())
        {
        	System.out.println(iter.next());
        }
        while (iter1.hasNext())
        {
        	System.out.println(iter1.next());
        }
        return answer;
	}
	
	public static void main(String[] args) {
		Solution sol = new Solution();
		
		String[] participant = {"a", "b", "c"};
		String[] completion = {"a", "c"};
		
		sol.solution(participant, completion);
	}
}