import foo.*; import java.util.*; class Test { public void main(Map<@NotNull String, @NotNull Integer> map, HashMap<@NotNull String, @NotNull Integer> hashMap) { Integer value = map.get("y"); if (value == null) { System.out.println("it's not contained"); } map.get("z").intValue(); value = hashMap.get("y"); if (value == null) { System.out.println("it's not contained"); } } public void main1(Map<@NotNull String, @Nullable Integer> map, HashMap<@NotNull String, @Nullable Integer> hashMap) { map.get("y").intValue(); hashMap.get("y").intValue(); } public void main2(Map<@NotNull String, @NotNull Integer> map, HashMap<@NotNull String, @NotNull Integer> hashMap) { Integer value = map.remove("y"); if (value == null) { System.out.println("it's not contained"); } value = hashMap.remove("y"); if (value == null) { System.out.println("it's not contained"); } } }