IsAssignableFrom () method in Java and instanceof () method usage

A sentence summary:

• The IsAssignableFrom () method is judged from the perspective of class inheritance , and theinstanceof () method is judged from the perspective of instance inheritance .
• The IsAssignableFrom () method is to determine whether a class is a parent class, and theinstanceof () method is to determine whether a class is a subclass.

1. Class.isassignablefrom () method

Class.isassignablefrom () is used to determine whether a class Class1 is the same as another class Class2 or a subclass or interface of another class.
The format is:

Class1.isassignablefrom (CLASS2) 

Both the caller and the parameter are java.lang.Class types.

2.class.instanceof () method

class.instanceof () is an instance of a class or interface that is used to determine whether an object instance is a subclass or a child of its subclasses.
The format is:

instanceof TypeName  

The first parameter is the object instance name, and the second argument is a specific class name or interface name, such as String,inputstream. Its return value is Boolean.

3. Specific usage

Turn from (http://sunnylocus.iteye.com/blog/555676)

 PackageCom.bill99.pattern; Public classAssignabletest { Publicassignabletest (String name) {}/*** Determine if a class is the parent of another class * is print true * No print false*/     Public Static voidtestIsAssignedFrom1 () {System.out.println ("String is the parent class of object:" +string.class. IsAssignableFrom (Object.class)); }    /*** Determine if a class is the parent of another class * is print true * No print false*/     Public Static voidtestIsAssignedFrom2 () {System.out.println ("Object is the parent of string:" +object.class. IsAssignableFrom (String.class)); }    /*** Determine if a class is the same as another class * is print true * No print false*/     Public Static voidtestIsAssignedFrom3 () {System.out.println ("Object and object are the same:" +object.class. IsAssignableFrom (Object.class)); }    /*** Determine if STR is an instance of the object class * is print true * No print false*/     Public Static voidtestInstanceOf1 () {String str=NewString (); System.out.print ("Str is an instance of object:"); System.out.println (strinstanceofObject); }    /*** Determine if O is an instance of the object class * is print true * No print false*/     Public Static voidTestInstanceOf2 () {Object o=NewObject (); System.out.print ("O is an instance of object:"); SYSTEM.OUT.PRINTLN (oinstanceofObject); }         Public Static voidMain (string[] args) {testIsAssignedFrom1 ();        TestIsAssignedFrom2 ();        TestIsAssignedFrom3 ();        TESTINSTANCEOF1 ();    TestInstanceOf2 (); }}

Results:

String is the parent class of object: False
object is the parent class of string: True
Object and object are the same: true
STR is an instance of object: True
O is an instance of object: True

IsAssignableFrom () method in Java and instanceof () method usage