Adding a value to a list to an already existing key in Map

Question

Evening!

I have the following Map:

HashMap myMap = new HashMap();

I then added th

Answer 1

import java.util.*;

class M {
    public static void main( String ... args ) {
        List l = new ArrayList<>();
        l.add("Test 1");
        l.add("Test 2");
        l.add("Test 3");

        Map> m = new HashMap<>();
        m.put("Tests", l );

        // some time later that day ... 
        m.computeIfAbsent("Tests", k -> new ArrayList<>()).add("Test 4");
        System.out.println(m);
    }
}