Class isInstance() method in Java with Examples

The isInstance() method of java.lang.Class class is used to check if the specified object is compatible to be assigned to the instance of this Class. The method returns true if the specified object is non-null and can be cast to the instance of this Class. It returns false otherwise.

Syntax:

public boolean isInstance(Object object)

Parameter: This method accepts object as parameter which is the specified object to checked for compatibility to this Class instance.

Return Value: This method returns true if the specified object is non-null and can be cast to the instance of this Class. It returns false otherwise.

Below programs demonstrate the isInstance() method.



Example 1:

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// Java program to demonstrate isInstance() method
  
public class Test {
    public static void main(String[] args)
        throws ClassNotFoundException
    {
  
        // returns the Class object for this class
        Class myClass = Class.forName("Test");
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString());
  
        // get the Class instance using forName() method
        Class c = Class.forName("java.lang.String");
  
        System.out.println("Class represented by c: "
                           + c.toString());
  
        // Check if object c is compatible
        // using isInstance() method
        System.out.println("Is c compatible: "
                           + myClass.isInstance(c));
    }
}

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Output:

Class represented by myClass: class Test
Class represented by c: class java.lang.String
Is c compatible: false

Example 2:

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// Java program to demonstrate isInstance() method
  
public class Test {
    public static void main(String[] args)
        throws ClassNotFoundException
    {
  
        // returns the Class object for this class
        Class myClass = Class.forName("Test");
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString());
  
        // get the Class instance using forName() method
        Class c = Class.forName("Test");
  
        System.out.println("Class represented by c: "
                           + c.toString());
  
        // Check if object c is compatible
        // using isInstance() method
        System.out.println("Is c compatible: "
                           + myClass.isInstance(c));
    }
}

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Output:

Class represented by myClass: class Test
Class represented by c: class Test
Is c compatible: false

Reference: https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#isInstance-java.lang.Object-

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