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Problem in Core Java

1 reply on 1 page. Most recent reply: Sep 2, 2002 12:19 PM by Kishori Sharan

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siddhartha

Posts: 15
Nickname: saddysan
Registered: Jul, 2002

Problem in Core Java

Posted: Sep 1, 2002 11:21 AM

Here is a small program:

public class AQuestion
{
public void method(Object o)
{
System.out.println("Object Version");
}
public void method(String s)
{
System.out.println("String Version");
}
public static void main(String args[])
{
AQuestion question = new AQuestion();
question.method(null);
}
}
Ourput is:
String Version

my doubt is why ?

saddy

Kishori Sharan

Posts: 211
Nickname: kishori
Registered: Feb, 2002

Re: Problem in Core Java

Posted: Sep 2, 2002 12:19 PM

It is because Java finds two methods matching null argument:
1. IT is String arg
2. It is Object arg

Now Java will choose which one is more specific and it finds that String argument method is more specific and that is why it calls that methods always. To find that which method is more specific, you can try to call other method from within the body of other one and see if it is possible. Object is not always a String, however a String is always an Object. So String version of method argument is more specific. Also, refer to JLS for more details on this topic. Here, null can be assigned to String as well as Object. However, String can also be assigned to Object and not vice versa.

Thanks
Kishori

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