Can an abstract class have a final method?

Question

Can an abstract class have a final method in Java?

Answer 1

Sure. Take a look at the Template method pattern for an example.

abstract class Game
{
    protected int playersCount;

    abstract void initializeGame();

    abstract void makePlay(int player);

    abstract boolean endOfGame();

    abstract void printWinner();

    /* A template method : */
    final void playOneGame(int playersCount) {
        this.playersCount = playersCount;
        initializeGame();
        int j = 0;
        while (!endOfGame()) {
            makePlay(j);
            j = (j + 1) % playersCount;
        }
        printWinner();
    }
}

Classes that extend Game would still need to implement all abstract methods, but they'd be unable to extend playOneGame because it is declared final.

An abstract class can also have methods that are neither abstract nor final, just regular methods. These methods must be implemented in the abstract class, but it's up to the implementer to decide whether extending classes need to override them or not.

Answer 2

Yes, it can. But the final method cannot be abstract itself (other non-final methods in the same class can be).