Why do I need the final def in the poll () method of LinkedList in Java

Question

/**
 * Retrieves and removes the head (first element) of this list.
 *
 * @return the head of this list, or {@code null} if this list is empty
 * @since 1.5
 */
public E poll() {
    final Node<E> f = first; //why final here? <<-------- ******* --------
    return (f == null) ? null : unlinkFirst(f);
}

Hi, I am reading the JDK 1.7 source code. In the above code snippet in LinkedList.java, I can’t understand why I need “final” in the poll () method. Why not:

public E poll() {
    return (first == null) ? null : unlinkFirst(first);
}

Can you share an understanding of the implementation? Thank.

Answer 1

Most methods on LinkedList use declarations finalfor local variables.

LinkedList JDK 1.7 Source

This is probably due to the concept of using the final "modifier, when applicable in java .

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Answer 2

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Answer 3

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