java instanceof 用法

刺骨的言语ヽ痛彻心扉 2022-03-17 16:44 193阅读 0赞

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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dzanp6Y2Jx_size_16_color_FFFFFF_t_70][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dzanp6Y2Jx_size_16_color_FFFFFF_t_70]: /images/20220317/30a9fd08cb1f4f4c821b412a033bf390.png