Re: Another DCL-like approach, correct or broken?

[...]

OK, so let's make it a bit simpler:

public abstract class SingletonReference<T> {

    private static final class ValueHolder<T> {
        final T value;

        ValueHolder(final T value) {
            this.value = value;
        }
    }

    private ValueHolder<T> valueHolder;

    protected abstract T initialValue();

    public final T get() {
        if (valueHolder == null) {

            synchronized (this) {
                if (valueHolder == null) {
                    valueHolder = new ValueHolder<T>(initialValue());
                }
            }
        }
        return valueHolder.value;
    }
}

Now, it's classic DCL idiom supported by final field initialization
semantics. No volatile field is used.

Do you think it's correct?