java instanceof 用法

java  instanceof 的用法，它的作用是判断其左边对象是否为其右边类的实例，返回boolean类型的数据；也可以用来判断继承中的子类的实例是否为父类的实现

 

示例如下

定义一个 Person 类

package nice.bean;

public class Person {
	
	private String head;
	
	private String body;

	public String getHead() {
		return head;
	}

	public void setHead(String head) {
		this.head = head;
	}

	public String getBody() {
		return body;
	}

	public void setBody(String body) {
		this.body = body;
	}

}

定义一个 User 类，继承 Person 类

package nice.bean;

public class User extends Person{
	
	private String userName;
	
	private String userPwd;
	
	private String userImg;

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getUserPwd() {
		return userPwd;
	}

	public void setUserPwd(String userPwd) {
		this.userPwd = userPwd;
	}

	public String getUserImg() {
		return userImg;
	}

	public void setUserImg(String userImg) {
		this.userImg = userImg;
	}

}

测试代码

package nice;

import nice.bean.Person;
import nice.bean.User;

public class DemoLL {
	
	public static void main(String[] args) {
		
		User user = new User();
		Person person = new Person();
		
		if(user instanceof User) {
			System.out.println("属于User类");
		}
		
		if(user instanceof Person) {
			System.out.println("属于Person类");
		}
		
		if(!(person instanceof User)) {
			System.out.println("不属于User类");
		}
	}

}

结果如下