Overloading and Overriding

[Sukesh Jain]

Hi All,

Can you please tell me what would be the outcome of the below program and the reason behind such outcome?

Thanks & Regards,
Sukesh.

class YourExtensiveKnowledgeTest extends YourKnowledgeTest {

    public void test() {
        System.out.println("If you expected this then your Java knowledge is not good");
    }
}

public class YourKnowledgeTest {

    private void test() {
        System.out.println("If you expected this then your Java knowledge is good");
    }

    /**
    * @param args
    */
    public static void main(String[] args) {
        YourKnowledgeTest test = new YourExtensiveKnowledgeTest();
        test.test();
    }

}

[Ankit Garg]

Hi Sukesh, welcome to javaranch

Sukesh please Use Code Tags when you post a source code. That way your code looks formatted. Unformatted code is hard to read. You can add code tags by wrapping your code in [code] [/code] tags. You can edit your message using button and then add code tags to it...

[Tom Reilly]

The YourKnowledgeTest.test() is private so YourExtensiveKnowledgeTest.test() is not overriding it. It is simply creating a method with the same name. Since your main() method is part of YourKnowledgeTest, you have access to the private method. Because you are assigning a reference to the YourExtensiveKnowledgeTest instance in a YourKnowledgeTest variable, the compiler only sees YourExtensiveKnowledgeTest as a YourKnowledgeTest and therefore calls the only test() method it knows about (the private one).

Note that had you moved the main() method to YourKnowledgeTest then you would have gotten a compiler error because the compiler does not have access to the private method test().

[Sukesh Jain]

Hi Tom,

Thanks for the explanation.

I thought the invocation of method is determined at runtime and not at compilation time. In this case, either it should result in runtime error as there is no overriding test method.

Thanks & Regards,
Sukesh.

PS @Ankit: Thanks for the code tag information.

[Michael Angstadt]

Sukesh Jain wrote:I thought the invocation of method is determined at runtime and not at compilation time. In this case, either it should result in runtime error as there is no overriding test method.

There's no error here. YourKnowledgeTest.test() is private, so YourExtensiveKnowledgeTest.test() does not override it. This means that when you call test.test() in your code, it calls YourKnowledgeTest.test().