ConcreteSubject

public class ConcreteSubject extends AbstractSubject {

    private static final int DEFAULT_SIZE = 10;
    private AbstractSpy[] arrayOfSpies = new AbstractSpy[DEFAULT_SIZE];

    public ConcreteSubject(int someNumber) {
        this.arrayOfSpies = new AbstractSpy[someNumber];
    }

    @Override
    public void notifySpies() {

        for (AbstractSpy abstractSpy : this.arrayOfSpies) {
            abstractSpy.updateSubjects(this);
        }
    }

    @Override
    public void addSpy(AbstractSpy spy) {
        // YOUR CODE HERE
    }

    public void action() {
        super.setState((int) Math.random());
        this.notifySpies();
    }
}