Overloading interface methods

[Vonique Leary]

Does Java allow interface methods to be overloaded?

Thanks,
Von

[Ernest Friedman-Hill]

Yes, absolutely.

[Vonique Leary]

Thanks, I thought so.

[Rob Spoor]

These kinds of questions can be easily answered by trying it out yourself with a little example.

[Shanky Sohar]

you cannot do like this.

public interface Testing {
	void dostuff();
}

public class testFor implements Testing{   
	void dostuff(int i){
		}   
}

but this is perfectly legal..

public interface Testing {
	void dostuff();
}

public class testFor implements Testing{   
	void dostuff(){
                }   
} 

[K Abhijit]

interface and Overloading are quite independent mechanism; we should not try to mix them ..

[Ernest Friedman-Hill]

K Abhijit wrote:interface and Overloading are quite independent mechanism; we should not try to mix them ..

I completely disagree. There's absolutely no reason why an interface shouldn't have overloaded methods. There are a number of such interfaces in the Java API; java.io.DataOutput has three overloaded write() methods, for example, and java.util.Collection has two overloaded toArray() methods. It's a perfectly fine thing to do.

Shanky Sohar wrote:you cannot do like this.

Well, indeed, you have to obey the rules of the Java lanaguage. Neither of these examples is what the original poster was asking about, though. If an interface includes both "Object[] toArray()" and "Object[] toArray(Object[])", then a class implementing this interface has to implement both overloaded methods, of course.

[K Abhijit]

@Ernest Friedman-Hill

I think you didn't get me right ... what I meant was something else....

When i said these 2 things are quite independent that DOESN'T mean that they can not co-exist...
it should be considered as OVERLOADING DOESN'T HAVE ANY IMPACT ON INTERFACE AND VICE VERSA....

[Shanky Sohar]

@Ernest Friedman-Hill

I was little confused.
So i presented both the thing that what can we do and what we cannot.

[K Abhijit]

Ernest Friedman-Hill wrote:Neither of these examples is what the original poster was asking about, though. If an interface includes both "Object[] toArray()" and "Object[] toArray(Object[])", then a class implementing this interface has to implement both overloaded methods, of course.

I think we all didn't get his original questions here.....

if interface itlsef contains Overloaded methods then this question is absolutely USELESS ..the entire Java Api is based on interfaces full of overloaded methods....

What he was trying to ask is: (this is a bit guess and Post Creator should correct me incase i'm wrong)

interface A{
void  doFoo();
}

class AImpl implements A{
void doFoo(){

//blablabla
}

void doFoo(int f){} .....

}

I think he is trying to ask if void doFoo(int f){} ..... is allowed or not...

Ans is Yes.. perfectly legal...

[Shanky Sohar]

@K Abhijit

Could you please use codetags while posting code.
Thanks

[Soniya Ahuja]

The reason why we have a plethora of answers all with different opinions is because the question is not clear. Vonique please be more specific and provide more description about your doubt - especially when there are different ways in which a question can be interpreted, else you can see what happens

[Shanky Sohar]

---------ignore this post please---------

[Vonique Leary]

Well, the reason I asked is because I am studying out of SCJP Sun Certified Programmer for Java 5 book and one of the questions is this:

<code>Given:

public abstract interface Frobnicate { public void twiddle(String s); }

Which is a correct class? (Choose all that apply.)

A. public abstract class Frob implements Frobnicate {
public abstract void twiddle(String s) { }
}

B. public abstract class Frob implements Frobnicate { }

C. public class Frob extends Frobnicate {
public void twiddle(Integer i) { }
}

D. public class Frob implements Frobnicate {
public void twiddle(Integer i) { }
}

E. public class Frob implements Frobnicate {
public void twiddle(String i) { }
public void twiddle(Integer s) { }
}

17.Given:

class Top {
public Top(String s) { System.out.print("B"); }
}</code>

and the answer involved this comment:
"D is incorrect because overloading a method is not implementing it."

So, I mistakenly assumed that interfaces do not allow overloading, but now I realize what they are saying is that the method may be overloaded as long as it is also implemented in its original form.

Anyway, hope that clears things up.

Thanks,
Von

[Vonique Leary]

What happened to the code tags?

[Abimaran Kugathasan]

Vonique Leary wrote:What happened to the code tags?

Have a look on this link => UseCodeTags <=. And you are correct!

[K Abhijit]

@ Von: use [ code ] [ / code ] instead like this..... ( to see actual message body try quoting ) ..

public abstract interface Frobnicate { public void twiddle(String s); } 

Which is a correct class? (Choose all that apply.)

A.

public abstract class Frob implements Frobnicate { 
public abstract void twiddle(String s) { } 
} 

B.

public abstract class Frob implements Frobnicate { } 

C.

public class Frob extends Frobnicate { 
public void twiddle(Integer i) { } 
} 

D.

public class Frob implements Frobnicate { 
public void twiddle(Integer i) { } 
} 

E.

public class Frob implements Frobnicate { 
public void twiddle(String i) { } 
public void twiddle(Integer s) { } 
} 

17.Given:

class Top { 
public Top(String s) { System.out.print("B"); } 
}</code> 

and the answer involved this comment:
"D is incorrect because overloading a method is not implementing it."

[K Abhijit]

@shanky : done

[Vonique Leary]

Oh, that's right. I'm thinking html with the < and /> tags.

Thanks!