Doubt regarding multiple and hybrid inheritance in java.

[chaitanya karthikk]

Hi everybody, I am Chaitanya. I have a doubt regarding inheritance in java. Java will not support multiple and hybrid inheritance.

What I know till now is suppose if I am having two classes namely A and B which has a method sample() in both classes. Suppose if class C is extending class A and B there arises an ambiguity.

class A
{
    public void sample()
    {
    }
}
class B
{
    public void sample()
    {
    }
}
public class c extends A, B
{
    public static void main(String kk[])
    {
    }
}

I know this is not possible. I am just figuring it out. Now the runtime environment gets confused if the user calls sample() method. So this is why java will not support multiple or hybrid inheritance.

Am I right?

If I am right then what about this approach where I am having two interfaces A and B having one unimplemented method a() in common. Now this code is valid.

interface A
{
	public void a();
}
interface B
{
	public void a();
}
public class InterfaceDemo implements A,B
{
	public static void main(String kk[])
	{
		
	}
	public void a()
	{
		
	}
}

Why does not java fall in confusion this time?

Please shed some light on my topic. Thank you all in advance.

[Henry Wong]

chaitanya karthikk wrote:
Why does not java fall in confusion this time?

There is no confusion because there is only one implementation -- doesn't matter if you want version A or version B, it is the same implementation.

Henry

[chaitanya karthikk]

Hi Henry I dint understand what you said. And please tell me what I quoted about multiple inheritance is correct or wrong.

Thank you in advance.

[Matthew Cox]

chaitanya karthikk wrote:Hi Henry I dint understand what you said. And please tell me what I quoted about multiple inheritance is correct or wrong.

Thank you in advance.

What he is saying is that in your second example, the compiler/run-time will make no differentiation between interface A.a() and B.a(). Since they have the same signature, return type, and name ... they are handled in the same fashion ... invoke a()

here is an example

public interface A
{
      void a();
}

public interface B
{
      void a();
}

public class Concrete extends A, B
{
    public void a()
    {
         System.out.println("No other implementation, other than me!");     
    }
}


public static void main(String[] args)
{ 
     Concrete c = new Concrete();
     A a = c;
     B b = c;
     
     c.a();
     a.a();
     b.a();
}

OUTPUT:
No other implementation, other than me!
No other implementation, other than me!
No other implementation, other than me!


The only method that could be invoked is a() ... A,B will both refer to a().

[Steve Luke]

The key here is that if you had multiple inheritance of classes, as in your example in the first post, then you have different behaviors inherited from the different classes. In the case of multiple interfaces with the same method signature, the resulting class only has a single behavior - the behavior of the method it implemented itself. The two interfaces each say the method must exist, but don't provide any behavior, so there can be no confusion about what should be done.

[chaitanya karthikk]

Hi Luke, thanks for the explanation, and thank you others.

Have a good day.

[Adam Richards]

Tip: You'll be getter responses if you use correct terminology. "Doubt" is the wrong word here. The right word would be "question" or "confusion," not "doubt."

[Jesper de Jong]

Adam, "doubt" is the word that Indian English speakers use most of the time when they mean "question". We're used to it here on the Ranch.

[Henry Wong]

Jesper de Jong wrote:Adam, "doubt" is the word that Indian English speakers use most of the time when they mean "question". We're used to it here on the Ranch.

To add to that, JavaRanch has lots of users whom primary language is not english. Unless it is an egregious offense, where the technical meaning of the question is changed to mean something else, let's all shy away from being grammar police please.

Henry

[fred rosenberger]

Henry Wong wrote:
JavaRanch has lots of users whom primary language is not english.
Henry

Shouldn't that be "for whom"?

[chaitanya karthikk]

Hey guys, thank you for telling me, I will try to frame the question in the right way from the next time.

[Paul Clapham]

fred rosenberger wrote:

Henry Wong wrote:
JavaRanch has lots of users whom primary language is not english.
Henry

Shouldn't that be "for whom"?

No, maybe it should be "whom's".