How to receive difference of maps in java?

Question

I have two maps:

Map map1;
Map map2;

I need to receive difference between these maps. Does exist ma

Answer 1

Simple way to do it. if you want complex way, you can change filter to compare value.

    Map map1 = new HashMap() {{
        put("A", "1");
        put("B", "2");
        put("C", "3");
    }};
    Map map2 = new HashMap() {{
        put("A", "1");
        put("B", "2");
        put("D", "3");
    }};
    Map newList = map1.keySet().stream().filter(str -> !map2.containsKey(str)).collect(Collectors.toMap(v -> v, v -> map1.get(v)));
    Map oldList = map2.keySet().stream().filter(str -> !map1.containsKey(str)).collect(Collectors.toMap(v -> v, v -> map2.get(v)));

    System.out.println(newList);
    System.out.println(oldList);