why protected methods are not allowed in a Interface

[Suman Mummaneni]

Hello every one,
I have very strange (some might think stupid) question for your guys.
I think the title it self explains a lot.

Why are protected methods not allowed in an Interface?

I have also found a bug regarding this. Its was closed in 1995 saying that protected method are no longer allowed in an interface.

It is strange because protected abstract method are allowed in an abstract class.

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The second questin is
Can we declare a public class inside a interface? If so how can this class be accessed
example:
interface a {
class b {
public b() {
}
public void test() {System.out.println("Print me:");
}
public void printIt();
}

Is the above example valid if so how is class b accessiable.

[Paul Sturrock]

Not an advanced question. Moving...

[Campbell Ritchie]

You can't have two public classes in the same file, but it appears one can have a non-public class within an interface.
For more explanation, read the Java Language Specification about interfaces. Since an interface is intended to provide members for implementing classes to be used in different packages, its members are implicitly public and abstract, so you don't say "public abstract." The intention is for the methods to be used by other classes, so they ought not to be "protected."

[Jim Yingst]

[Campbell Ritchie]: it appears one can have a non-public class within an interface.

Any class declared directly inside an interface is implicitly public (and static). Just as any method declared in and interface is implicitly public (and nonstatic), and any field declared there is implicitly public, static, and final.

[Suman Mummaneni ]: If so how can this class be accessed

It's accessed just like any static nested class. In your example:

a.b ab = new a.b();
ab.test();

Incidentally many of us find it confusing to talk about classes with names which violate standard naming conventions. So it would be preferable if your example used class names like A and B rather than a and b. Thanks.

[Campbell Ritchie]

Thank you, Jim Yingst. Presumably you just miss out the "public".

[Suman Mummaneni]

Thank you guys. But I still did not get the answer WHY are protected method not allowed in a interface.

[Campbell Ritchie]

Because the methods of an interface are intended to form the public face of the implementing class. If they were "protected," they would have what is to all intents and purposes private access in implementing classes.

[Suman Mummaneni]

thank you Campbell, this has cleared a lot of issues for me.