Implementing generic method from an interface in Java

Question

I am trying to implement simple queue in Java from an interface, but I'm getting an error:

Error:(9, 17) java: name clash: enqueue(T) in main.QueueImpl and enqueue(java.lang.Object) in main.Queue have the same erasure, yet neither overrides the other

Here is my code:

Interface:

public interface Queue<T> {

    void enqueue(T o);

    T dequeue();

    int size();
}

Implementation:

public class QueueImpl<T> implements Queue {
LinkedList<T> queue = new LinkedList<>();

@Override
public void enqueue(T o) {
    queue.add(o);
}

@Override
public T dequeue() {
    return queue.poll();
}

@Override
public int size() {
    return queue.size();
 }
}

What's the problem with implementing enqueue method?

You're using generics, so you don't want to implement `Queue`, you want to implement `Queue`. Silly typo, easy to fix. — Mike 'Pomax' Kamermans, Jun 27 '18 at 21:45

score 3 · Accepted Answer · answered Jun 27 '18 at 21:42

3

Change your implementation to pass the generic to the interface. Like,

public class QueueImpl<T> implements Queue<T> {

As is, it knows Queue is generic, but it's treated as a raw type.

answered Jun 27 '18 at 21:42

Elliott Frisch

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That's it, thank You. – steve1337 Jun 27 '18 at 21:44

Implementing generic method from an interface in Java

1 Answers1