Trying to implement the Builder pattern with inheritance

Question

This is just a bit long, but don't worry, it's very understandable.
I'm applying the Builder pattern found in Effective Java (J. Bloch). The pattern is avaiable right here :
http://books.google.fr/books?id=ka2VUBqHiWkC&lpg=PA15&ots=yXGmIjr3M2&dq=nutritionfacts%20builder%20java&pg=PA14
My issue is due to the fact that I have to implement that pattern on an abstract class and its extensions. I have declared a Builder inside the base class, and the extensions specify their own extension of the base's Builder.
The abstract base class is roughly this :
public abstract class Effect extends Trigger implements Cloneable {
    protected Ability parent_ability;
    protected Targetable target;
    protected EffectBinder binder;
    protected Effect(){
    protected Effect(EffectBuilder parBuilder){
        parent_ability = parBuilder.parent_ability;
        target = parBuilder.target;
        binder = parBuilder.binder;
    public static class EffectBuilder {
        protected Ability parent_ability;
        protected Targetable target;
        protected EffectBinder binder;
        protected EffectBuilder() {}
        public EffectBuilder(Ability parParentAbility) {
            parent_ability = parParentAbility;
        public EffectBuilder target(Targetable parTarget)
        { target = parTarget; return this; }
        public EffectBuilder binder(EffectBinder parBinder)
        { binder = parBinder ; return this; }
    // etc.
}And the following is one of its implementation :
public class GainGoldEffect extends Effect {
    private int gold_gain;
    public GainGoldEffect(GainGoldEffectBuilder parBuilder) {
        super(parBuilder);
        gold_gain = parBuilder.gold_gain;
    public class GainGoldEffectBuilder extends EffectBuilder {
        private int gold_gain;
        public GainGoldEffectBuilder(int parGoldGain, Ability parParentAbility) {
            this.gold_gain = parGoldGain;
            super.parent_ability = parParentAbility;
        public GainGoldEffectBuilder goldGain(int parGoldGain)
        { gold_gain = parGoldGain; return this; }
        public GainGoldEffect build() {
            return new GainGoldEffect(this);
    // etc.
}Effect requires 1 parameter to be correctly instantiated (parent_ability), and 2 others that are optional (target and binder). Implementing the Builder Pattern means that I won't have to rewrite specific construcors that cover all the combination of parameters of the Effect base class, plus their own parameter as an extension. I expect the gain to be quite huge, as there will be at least a hundred of Effects in this API.
But... in the case of these 2 classes, when I'm trying to create the a GoldGainEffect like this :
new GainGoldEffect.GainGoldEffectBuilder(1 , locAbility).goldGain(5);the compiler says "GainGoldEffect is not an enclosing class". Is there something wrong with the way I'm trying to extend the base Builder ?
I need your help to understand this and find a solution.
Thank you for reading.

Answer 1

The GainGoldEffectBuilder class must be static.
Otherwise a Builder would require a GainGoldEffect object to exist, which is backwards.