考虑这个HashMap扩展(如果它为null，则在调用“get”时生成V类的实例)publicclassHashMapSafeextendsHashMapimplementsMap{privateClassdataType;publicHashMapSafe(Classclazz){dataType=clazz;}@SuppressWarnings("unchecked")@OverridepublicVget(Objectkey){if(!containsKey(key)){try{put((K)key,dataType.newInstance());}catch(Instantia