How to find the most common element(s) using Map (or Set ? ) in Java?

Question

I've got names in an ArrayList , and I would like to find the most common element in the simplest way. I tried to use Collectoins.max() , but it's return value was incorrect.

I created a HashMap, using names az Keys and quantity of names as Values, but I couldn't figure out how to write the names with the highest values.

( Actually, if there is two or more names with highest values, I have to get all of them. )

Answer 1

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

public class StringChecker {

public static void main(String[] args) {
    ArrayList<String> string;
    string = new ArrayList<>(Arrays.asList("Mah", "Bob", "mah", "bat", "MAh", "BOb"));
    Map<String, Integer> wordMap = new HashMap<String, Integer>();

    for (String st : string) {
        String input = st.toUpperCase();
        if (wordMap.get(input) != null) {
            Integer count = wordMap.get(input) + 1;
            wordMap.put(input, count);
        } else {
            wordMap.put(input, 1);
        }
    }
    System.out.println(wordMap);
    Object maxEntry = Collections.max(wordMap.entrySet(), Map.Entry.comparingByValue()).getKey();
    System.out.println("maxEntry = " + maxEntry);
}

}