迭代器模式

Iterator（迭代器接口）：
ConcreteIterator（迭代器实现类）：
Aggregate（容器接口）：
ConcreteAggregate（容器实现类）：

public interface IDieDai<T> {
    Boolean hasNext();

    T next();

}

public class DieDai<T> implements IDieDai<T> {
    ArrayList<T> list = new ArrayList<>();

    public DieDai(ArrayList<T> list) {
        this.list = list;
    }

    int size = 0;

    @Override
    public Boolean hasNext() {
        return size != list.size();
    }

    @Override
    public T next() {
        T value = null;
        if (hasNext() == true) {
            value = this.list.get(size++);
        }
        return value;
    }

}

public interface IContainer<T> {
    void add(T t);

    void remove(T t);

    IDieDai dieDai();
}

public class Container<T> implements IContainer<T> {
    ArrayList<T> list = new ArrayList<>();

    @Override
    public void add(T o) {
        list.add(o);
    }

    @Override
    public void remove(T o) {
        list.add(o);
    }

    @Override
    public IDieDai dieDai() {
        return new DieDai(this.list);
    }
}

测试

public class Test {
    public static void main(String[] args) {
        Container<String> stringContainer = new Container<>();
        stringContainer.add("hello");
        stringContainer.add("world");
        IDieDai iDieDai = stringContainer.dieDai();
        while (iDieDai.hasNext()){
            System.out.println(iDieDai.next());
        }
    }
}