Java类型信息-instanceof、isInstance()、==、equals比较

在查询类信息时，instanceof、isInstance()产生的结果相同，==、equals产生的结果相同。示例：

class Parent {}
class Son extends Parent {}
public class Test {
    public static void main(String[] args) {
        test(new Parent());
        print("
");
        test(new Son());
    }

    private static void test(Object o) {
        print("Testing o of type:"+o.getClass());

        //instanceof
        print("o instanceof Parent:"+(o instanceof Parent));
        print("o instanceof Son:"+(o instanceof Son));

        //isInstance
        print("Parent.isInstance(o):"+ Parent.class.isInstance(o));
        print("Son.isInstance(o):"+ Son.class.isInstance(o));

        //==
        print("o.getClass == Parent.class :"+(o.getClass()==Parent.class));
        print("o.getClass == Son.class :"+(o.getClass()==Son.class));

        //equals
        print("o.getClass.equals(Parent.class) :"+(o.getClass().equals(Parent.class)));
        print("o.getClass.equals(Son.class) :"+(o.getClass().equals(Son.class)));

    }
    private static void print(String s){
        System.out.println(s);
    }
}

结果：

Testing o of type:class com.freesky.basic.classt.Parent
o instanceof Parent:true
o instanceof Son:false
Parent.isInstance(o):true
Son.isInstance(o):false
o.getClass == Parent.class :true
o.getClass == Son.class :false
o.getClass.equals(Parent.class) :true
o.getClass.equals(Son.class) :false


Testing o of type:class com.freesky.basic.classt.Son
o instanceof Parent:true
o instanceof Son:true
Parent.isInstance(o):true
Son.isInstance(o):true
o.getClass == Parent.class :false
o.getClass == Son.class :true
o.getClass.equals(Parent.class) :false
o.getClass.equals(Son.class) :true

instanceof、isInstance()保持了类型的概念，指的是“你是这个类，或者是这个累的派生类吗？”；==、equals比较的是实际的、确切的Class对象，没有考虑继承