instanceof & isAssignableFrom的异同

• instance 关注的是实例是否为类或接口的一个实例
• isAssignableFrom 关注的是Class对象是否相同，或者Class1是Class2的超类或接口
  • Class1.isAssignableFrom(Class2)　　

一、验证代码如下

package com.cctest.veritydemo;

/**
 * @author: gkyang
 * @date: 2019-03-05
 * @description:
 */

interface ClassDemoInteface {

}

class ClassDemoParent {

}

public class ClassDemo extends ClassDemoParent implements ClassDemoInteface{

    public static void main(String[] args) {

        ClassDemo cd = new ClassDemo();

        /* ----------- instance ------------*/
        System.out.println(cd instanceof ClassDemo);    // true
        System.out.println(cd instanceof ClassDemoParent);   // true
        System.out.println(cd instanceof ClassDemoInteface);   // true
        System.out.println(cd instanceof Object);

        /* ----------- isAssignableFrom ----------*/
        System.out.println(ClassDemo.class.isAssignableFrom(ClassDemo.class));  // true

        System.out.println(ClassDemo.class.isAssignableFrom(ClassDemoParent.class));  // false
        System.out.println(ClassDemo.class.isAssignableFrom(ClassDemoInteface.class));    // false

        System.out.println(ClassDemoParent.class.isAssignableFrom(ClassDemo.class));    // true
        System.out.println(ClassDemoInteface.class.isAssignableFrom(ClassDemo.class));    // true

    }

}