Classes not extending java.lang.object

[Jitender Kumar]

Are there any classes which donot extend java.lang.Object?
If not, why are the methods in Object made protected instead of public?


Thanks,
Jitender.

[Chris Allen]

The only classes which do not extend Object are the primitives (i.e. int, float, double, char, long, String).

[Jitender Kumar]

Hi Chris,
Primitives are not java objects. Hence java contains wrapper classes (java.lang.Integer etc., that also extends java.lang.Object) for int, char and other primitive types.

String is not a primitive type and it very much extends java.lang.Object.

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/String.html


Thanks,
Jitender.

[Chris Allen]

Thanks for the correction on String. I knew there were 8 in total so the other three I missed were short, boolean, and byte. Good question on the protected modifier. Perhaps they only want these methods to be called by objects and not the primitives.

[Jitender Kumar]

[marc weber]

Originally posted by Jitender Kumar:
Are there any classes which donot extend java.lang.Object?
If not, why are the methods in Object made protected instead of public? ...

Good question! Indeed, all classes extend Object.

Two methods in Object (clone and finalize) have protected access. To understand why, see "using a trick with protected" from Appendix A in Bruce Eckel's Thinking in Java.

[Bert Bates]

Hey Chris!

I have to assume you're studying for your SCJP exam - cool! In this thread I think you have some of your Java definitions a little sideways...ya wanna take another shot at your answers? I'm asking because we wouldn't want all the lurkers out there to be getting the wrong impression of how Java works