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

问题描述

instanceof 可用于测试对象是给定类的直接实例还是后代实例.instanceof 也可以与接口一起使用，即使接口不能像类一样被实例化.谁能解释一下 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，我们可以在中存储实现特定interface的类的instances>接口引用变量像这样.

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 Testable {

    public static void main(String[] args) {

        Testable testable = new Test();

        // OR

        Test test = new Test();

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

interface Testable {

}

即，任何实现特定接口的运行时实例都将通过instanceof测试

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

编辑

和输出

instanceof succeeded
instanceof succeeded

@RohitJain

你可以像这样使用匿名内部类来创建接口的实例

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");
    }
};

并且您测试实例是接口类型，使用像这样的 instanceof 运算符

and you test the instance is of type interface, using instanceof operator like this

System.out.println(runnable instanceof Runnable);

结果为真"

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