迭代器模式
2009-06-29 12:45 Peter Yao 阅读(250) 评论(0) 编辑 收藏 举报Iterator
public interface Iterator { Object next(); void first(); void last(); boolean hasNext(); }
ConcreteIterator
public class IteratorImpl implements Iterator { private List list; private int index; public IteratorImpl(List list) { index = 0; this.list = list; } public void first() { index = 0; } public void last() { index = list.getSize(); } public Object next() { Object obj = list.get(index); index++; return obj; } public boolean hasNext() { return index < list.getSize(); } }
Aggregate
public interface List { Iterator iterator(); Object get(int index); int getSize(); void add(Object obj); }
ConcreteAggregate
public class ListImpl implements List { private Object[] list; private int index; private int size; public ListImpl() { index = 0; size = 0; list = new Object[100]; } public Iterator iterator() { return new IteratorImpl(this); } public Object get(int index) { return list[index]; } public int getSize() { return this.size; } public void add(Object obj) { list[index++] = obj; size++; } }
Test
public class Test { public static void main(String[] args) { List list = new ListImpl(); list.add("a"); list.add("b"); list.add("c"); //第一种迭代方式 Iterator it = list.iterator(); while (it.hasNext()) { System.out.println(it.next()); } System.out.println("====="); //第二种迭代方式 for (int i = 0; i < list.getSize(); i++) { System.out.println(list.get(i)); } } }
result
a b c ===== a b c