迭代器模式

public interface Iterator<E> {
    boolean hasNext();
    E next();
}

public interface Container<E> {
    Iterator<E> iterator();
}

public class ContainerConcrete<E> implements Container {

    // 存放的元素
    public String[] elements = {"A", "B", "C", "D"};

    @Override
    public Iterator iterator() {
        return new IteratorConcrete();
    }

    private class IteratorConcrete<E> implements Iterator {

        int index;

        @Override
        public boolean hasNext() {
            if (index < elements.length) {
                return true;
            }
            return false;
        }

        @Override
        public E next() {
            if (this.hasNext()) {
                return (E) elements[index++];
            }
            return null;
        }
    }
}

public class Test {

    public static void main(String[] args) {
        ContainerConcrete containerConcrete = new ContainerConcrete();
        Iterator iterator = containerConcrete.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }
}