overriding method in interface

[oll3i]

public interface IQResStack {
        void push(IAbstractQueryResult a);
 
}
 
public class QResStack implements IQResStack{
 
 public void push(AbstractQueryResult a){
 }
 

it says it does not overide the method in interface?

[Nepomuk]

Well, it doesn't. The interface defines a function that overrides a function that takes an IAbstractQueryResult which, judging by the name, is an interface. The class however has a function taking an AbstractQueryResult which is a class. That won't work.

Also when overriding a method it is good practice to use the @Overrides annotation; that way the IDE you're using will tell you when something goes wrong with overriding.

So, the end result would look like this:

public class QResStack implements IQResStack {
 
    @Override
    public void push(IAbstractQueryResult a) {
    }
}

[oll3i]

what about pop()
it says that it does not override the method in the supertype

[Nepomuk]

I see no pop() function in your code. However if you're getting that error I guess you've added the @Override annotation to it? You can only do that legally if your function is actually overriding a function from a supertype, i.e. parent class or implemented interface. And there are some limits; the signatures of the functions have to match and you can't override private or final functions and you can't override anything but methods.

[oll3i]

so it's like that? that works

@Override
public IAbstractQueryResult pop () {
return aR;
  }
@Override
public void push(IAbstractQueryResult a) { 
    }

[Nepomuk]

I'm guessing your interface looks like this:

public interface IQResStack {
 
        IAbstractQueryResult pop();
 
        void push(IAbstractQueryResult a);
}

correct? If so then yes, your use of the @Override annotation should be valid.