Java – interface extends itself

I have used this website for about 6 months, and it's time to ask my first question, because I can't find the answer, at least not an answer I can understand!

In this code, why does this interface extend?

public interface PositionedVertex<V extends PositionedVertex<V>> {

/**
 * @return Position for node data.
 */
public Point getPosition();
}

Won't this code do the same?

public interface PositionedVertex<V> {

/**
 * @return Position for node data.
 */
public Point getPosition();
}

Thank you in advance!

Solution

The interface is not extended< The V extension positionedvertex < V > is a generic type of binding associated with your interface This simply means that the generic type parameter of any class that implements this interface must be positionedvertex