Java设计模式：迭代器模式

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

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import java.util.ArrayList;
import java.util.List;

public abstract class AbstractObjectList<E> {
	protected List<E> list = new ArrayList<E>();

	public AbstractObjectList() {

	}

	public AbstractObjectList(List list) {
		this.list = list;
	}

	public void add(E e) {
		this.list.add(e);
	}

	public E get(int index) {
		return list.get(index);
	}

	public int size() {
		return list.size();
	}

	public boolean isEmpty() {
		return list.isEmpty();
	}

	public abstract AbstractIterator iterator();
}

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import java.util.List;

/**
 * 抽象对象列表的实现。
 * 
 * @author zhangfly
 *
 */
public class ObjectListImpl extends AbstractObjectList {
	public ObjectListImpl() {

	}

	public ObjectListImpl(List list) {
		super(list);
	}

	@Override
	public AbstractIterator iterator() {
		return new IteratorImpl(this);
	}
}

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/**
 * 迭代器的实现。
 * 
 * @author zhangfly
 *
 * @param <T>
 */
public class IteratorImpl<E> implements AbstractIterator {
	private AbstractObjectList<E> list;
	private int cursor = 0;

	public IteratorImpl(AbstractObjectList list) {
		this.list = list;
	}

	@Override
	public boolean hasNext() {
		if (list.isEmpty()) {
			return false;
		}

		if (cursor < list.size()) {
			return true;
		}

		return false;
	}

	@Override
	public E next() {
		E e = null;
		if (cursor < list.size()) {
			e = list.get(cursor);
			cursor++;
		}

		return e;
	}
}

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public class Test {
	public Test() {

		ObjectListImpl listImpl = new ObjectListImpl();
		
		// 添加三个不同类型的元素。
		listImpl.add(new String("zhang"));
		listImpl.add(new Exception("phil"));
		listImpl.add(2019);

		// 迭代器遍历。
		AbstractIterator iterator = listImpl.iterator();
		while (iterator.hasNext()) {
			System.out.println(iterator.next().toString());
		}
	}

	public static void main(String[] args) {
		new Test();
	}
}

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zhang
java.lang.Exception: phil
2019