Review

HashMap.get() throws if the key is null. Since you don't know which implementation of Map you get, you should always guard against this.

Check that the key is not null before calling Map.get().

• missing/condition/null_check

mubench/examples/survey/Maps.java

keyMayBeNull(HashMap, String)

class Maps {
	Object keyMayBeNull(HashMap<String, Object> m, String key) {
		return m.get(key);
	}

}

public class CheckKeyNotNull {
	public Object pattern(HashMap<String, Object> m, String key) {
		if (key != null) {
			return m.get(key);
		} else {
		  return null;
		}
	}
}