Determine the Class of an Object in Java

Exercise:

Write a Java Program to determine the class of an object.

1.Check using getClass()

Click Here to View the Solution!
//Declaring 2 Classes
class First    {
}
class Second    {
}
public class Main {
    public static void main(String[] args) {
      
        // create objects
        First obj1 = new First ();
        Second obj2 = new Second();

        // get the class of the objects
        System.out.print("The class of obj1 is: ");
        System.out.println(obj1.getClass());
        System.out.print("The class of obj2 is: ");
        System.out.println(obj2.getClass());
    }
}
Click Here to View the Output!
The class of obj1 is: class First
The class of obj2 is: class Second
Click Here to View the Explanation!
  • This program is used to find the class of an object by using the getClass() method.
  • Initially, two classes First and Second are initialized without any body.
  • In the Main class, two objects obj1 and obj2 are created of these two classes.
  • Now, to get the classes of these objects, a getClass() method of the class Object is used as follows: obj1.getClass() and obj2.getClass().
  • Finally, the output of the both the methods are printed that will display the class of each object.

2.Check using  instanceOf operator

Click Here to View the Solution!
class TestClass {
//created class to pass as parameter
}

public class Main {
    public static void main(String[] args) {
        TestClass obj = new TestClass();

        // check if obj is an object of Test
        if(obj instanceof TestClass) {
            System.out.println("obj is an object of the Test class");
        }
        else {
            System.out.println("obj is not an object of the Test class");
        }
    }
}
Click Here to View the Output!
obj is an object of the Test class
Click Here to View the Explanation!
  • This program is used to find the class of an object by using an operator instanceOf.
  • Initially, a class TestClass is created without any body.
  • In the Main class, an object obj of the class TestClass is created.
  • Now, to check whether obj is an instance of the class TestClass, an operator instanceOf is used inside an if..else statement as follows: (obj instanceOf TestClass).
  • If the condition is true, then the message “obj is an instance of the class Test Class” is printed. Else, “obj is not an instance of the class Test Class”.