问题:
new 类(),所创建的对象,每new一次都是一个新的对象。
那么通过反射newInstance()获得的对象,是同一个吗?
@Test public void test03() throws InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException { Class clsClass = Cls.class; Class clsClass2 = Cls.class; Class clsClass3 = Cls.class; Class clsClass4 = Cls.class; Cls instance = (Cls)clsClass.newInstance(); System.out.println("instance:"+instance.hashCode()); Cls instance2 = (Cls)clsClass2.newInstance(); System.out.println("instance2:"+instance2.hashCode()); if(instance == instance2){ System.out.println("赋值前instance==instance2:true"); }else{ System.out.println("赋值前instance==instance2:false"); } instance.setName("李四"); System.out.println("instance:"+instance.hashCode()); instance2.setName("王五"); System.out.println("instance2:"+instance2.hashCode()); if(instance == instance2){ System.out.println("赋值后instance==instance2:true"); }else{ System.out.println("赋值后instance==instance2:false"); } System.out.println("************************************"); Cls instance3 = (Cls)clsClass3.newInstance(); Cls instance4 = (Cls)clsClass4.newInstance(); Cls instance42 = (Cls)clsClass4.newInstance(); System.out.println("instance3:"+instance3.hashCode()); System.out.println("instance4:"+instance4.hashCode()); System.out.println("instance42:"+instance42.hashCode()); if(instance4 == instance42){ System.out.println("同一个Class对象instance4==instance42:true"); }else{ System.out.println("同一个Class对象instance4==instance42:false"); } } 结果: instance:6061 instance2:6061 赋值前instance==instance2:false instance:49685123 instance2:55290359 赋值后instance==instance2:false ************************************ instance3:6061 instance4:6061 instance42:6061 同一个Class对象instance4==instance42:false
①通过反射n创建对象,和new 类()创建对象一样.每newInstance()一次都是新的对象.
②hash值相等,但是通过==判断,不是同一个对象.
遗留问题:一个对象,赋值前后,hash值变化了.为什么?
可能答案:同样的 hashcode 有多个对象,未实例化之前为了方便在内存中查找这些个对象使用了同样的hash值,实例化之后改变了hash值,就明显不一样了.
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