Multiple Inheritance problem persists in Interfaces

[Suvojit Chakraborty]

Hi,
I tentatively made a program and found that multiple inheritance problem of C++ persists even with interfaces. Although this is definetely a special case but I want to know what is this problem known as( i know that this is perhaps known as diamond problem in C++). And is there a way out of this thing.

  interface one
{
	int i=10;
}
interface two
{
	int i=20;
}
interface z extends one,two
{
}
public class xyz implements z
{
	public static void main(String [] a)
	{
	System.out.println(i);
	}
}  

Output

D:\Education\Java\JavaStudyRoom\Applets>javac xyz.java
xyz.java:16: reference to i is ambiguous, both variable i in one and variable i
in two match
System.out.println(i);
^
1 error

Thanks for replying

[Dave Lorde]

Disambiguation - it's the same solution as in C++ : you have to specify which of the constants you want to use:

System.out.println(two.i);
// or
System.out.println(one.i);

Incidentally, you'll find it a lot easier to follow code if you use the Java naming conventions - type names begin with an uppercase letter, method and variable names begin with a lowercase letter.

[Rob Spoor]

I think the error message is clear: which i do you want? Dave's solution removes the ambiguity.

[Suvojit Chakraborty]

Dave Lorde wrote:Disambiguation - it's the same solution as in C++ : you have to specify which of the constants you want to use:

System.out.println(two.i);
// or
System.out.println(one.i);

Incidentally, you'll find it a lot easier to follow code if you use the Java naming conventions - type names begin with an uppercase letter, method and variable names begin with a lowercase letter.

Oh i see. So we take the same old C++ approach.
But I want to ask, why do we then say that Java has overcome the diamond problem of C++ by abandoning multiple inheritance. We still can end up in such situations in Java.

[Matthew Brown]

In C++ this conflict also applies to implementation. That's what Java prevents, since interfaces include the method protocols only and cannot contain method implementation.