Java中isAssignableFrom,instanceof

isAssignableFrom
Example: Class1.isAssignableFrom(Class2)
Explanation: ① Determine whether Class1 and Class2 are the same.

  System.out.println(Object.class.isAssignableFrom(Object.class)); // true  

          ② Whether Class1 is the parent class or interface of Class2.

System.out.println(Object.class.isAssignableFrom(String.class)); // true  

System.out.println("Object类是String 类的父类:"+
                        Object.class.isAssignableFrom(String.class));//true
System.out.println("AbstractList类是ArrayList 类的父类:"+
              AbstractList.class.isAssignableFrom(new ArrayList<>().getClass()));//true
System.out.println("List接口是ArrayList 类的父类:"+
             List.class.isAssignableFrom(new ArrayList<>().getClass()));//true
System.out.println("List接口是AbstractList 接口(抽象类)的父接口:"+
            List.class.isAssignableFrom(AbstractList.class));//true

According to the relationship between ArrayList, AbstractList and List, isAssignableFrom can also judge whether class1 is the parent interface (abstract class) of class2

instanceof
example: object instanceof TypeName
Explanation: Determine whether an object instance is an instance of a class or interface or its subclass subinterface.

public void testInstanceOf1() {  
           String ss = "";  
	   
	   System.out.println(ss instanceof Object); // true 
	   
       System.out.println(ss instanceof java.lang.String); // true  
       
       
       ArrayList<String>array=new ArrayList<>(); 
       
       System.out.println(array  instanceof java.util.List); // true 
    }  

 

 

The above is recorded as a daily note.over