package object_out; import java.util.HashMap; import java.util.concurrent.ConcurrentHashMap; public class TestAddItem { ConcurrentHashMap hm = new ConcurrentHashMap(); void doCommonMethods() { hm.clear(); hm.containsKey("a_key"); hm.containsValue("a_value"); hm.entrySet(); hm.get("a_key"); hm.isEmpty(); hm.keySet(); hm.put("a_key","a_value"); hm.putAll(new HashMap()); hm.remove("a_key"); hm.size(); hm.values(); } }