instanceof如何在接口上工作 [英] How instanceof will work on an interface

问题描述

instanceof 可用于测试对象是否是给定类的直接或下降实例。 instanceof 也可以与接口一起使用，即使接口不能像类一样实例化。任何人都可以解释 instanceof 是如何工作的？

instanceof can be used to test if an object is a direct or descended instance of a given class. instanceof can also be used with interfaces even though interfaces can't be instantiated like classes. Can anyone explain how instanceof works?

推荐答案

首先，我们可以在接口引用变量接口的类的实例 c $ c>喜欢这个。

First of all, we can store instances of classes that implements a particular interface in an interface reference variable like this.

package com.test;

public class Test implements Testeable {

    public static void main(String[] args) {

        Testeable testeable = new Test();

        // OR

        Test test = new Test();

        if (testeable instanceof Testeable)
            System.out.println("instanceof succeeded");
        if (test instanceof Testeable)
            System.out.println("instanceof succeeded");
    }
}

interface Testeable {

}

即，任何实现特定接口的运行时实例都将传递 instanceof test

ie, any runtime instance that implements a particular interface will pass the instanceof test

编辑

和输出

instanceof succeeded
instanceof succeeded

@RohitJain

@RohitJain

您可以使用这样的匿名内部类创建接口实例

You can create instances of interfaces by using anonymous inner classes like this

Runnable runnable = new Runnable() {

    public void run() {
        System.out.println("inside run");
    }
};

并使用 instanceof 这样的运算符

System.out.println(runnable instanceof Runnable);

，结果为'true'

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