LinkedList in Java: Why it directly implements List when it indirectly from extended class

Question

I see the following class hierarch, for LinkedList in Java.

public interface Collection<E>
extends Iterable<E>


public abstract class AbstractCollection<E>
extends Object
implements Collection<E>


public abstract class AbstractList<E>
extends AbstractCollection<E>
implements List<E>

public abstract class AbstractSequentialList<E>
extends AbstractList<E>

public class LinkedList<E>
extends AbstractSequentialList<E>
implements List<E>, Deque<E>, Cloneable, Serializable

Observing this hierarchy, why LinkedList need to mention implements List<E> when it is indirectly coming from AbstractList<E>.

Is there any reason to do so?

EDIT

Screenshot of the actual code (from rt.jar)

It does not. Javadoc however **documents** it. Because it is documentation tool. — Elliott Frisch, Jun 06 '20 at 21:48
@ElliottFrisch: It does in actual source code, adding the snippet of code. — CuriousMind, Jun 06 '20 at 21:50
The dupe answers the equivalent question for `ArrayList`; the reasoning equally applies to `LinkedList`. — Andy Turner, Jun 06 '20 at 21:54
Sure, let me check. I guess @Hari Menon provided a plausible reason. — CuriousMind, Jun 06 '20 at 21:55

score 2 · Accepted Answer · answered Jun 06 '20 at 21:50

2

No, it has no impact in terms of language semantics in this case. I imagine they just put it to make it clearer that it implements List as well, without the developer having to traverse the full hierarchy.

answered Jun 06 '20 at 21:50

Hari Menon

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LinkedList in Java: Why it directly implements List when it indirectly from extended class

1 Answers1