java设计模式之迭代器模式

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迭代器模式：提供一种方法顺序访问一个聚合对象中的各个元素，而又不暴露其内部的表示。

类图：
这里写图片描述
使用迭代器模式，实现了烤鱼菜单，类图：

MenuItem类代码实现：

public class MenuItem {    String name;    public MenuItem(String name){        this.name = name;    }    public String getname(){        return name;    }}

接口Iterator代码实现：

public interface Iterator {    public boolean hasNext();    public Object next();    public void remove();}

类FishIterator代码实现：

public class FishIterator implements Iterator{    MenuItem[] items;    int position = 0;    public FishIterator(MenuItem[] items){        this.items = items;    }    @Override    public boolean hasNext() {        // TODO Auto-generated method stub        if (position >=items.length || items[position] == null) {            return false;        }else {            return true;        }    }    @Override    public Object next() {        // TODO Auto-generated method stub        MenuItem menuItem = items[position];        position = position + 1;        return menuItem;    }    @Override    public void remove() {        // TODO Auto-generated method stub        for (int i = position; i < (items.length -1); i++) {            items[i] = items[i+1];        }        items[items.length - 1] = null;    }}

接口Menu代码实现：

public interface Menu {    public Iterator createIterator();}

类FishMenu代码实现：

public class FishMenu implements Menu{    MenuItem[] items;    static final int MAX_ITEMS = 6;    int numberOfItems = 0;    public FishMenu(){        items = new MenuItem[MAX_ITEMS];        addItem("烤鲫鱼");        addItem("烤草鱼");        addItem("烤大头鱼");        addItem("烤秋刀鱼");        addItem("烤鲨鱼");    }    public void addItem(String name){        MenuItem menuItem = new MenuItem(name);        if (numberOfItems >= MAX_ITEMS) {            System.out.println("Sorry,menu if full!can't add item to menu");        }else {            //System.out.println("menuItem="+menuItem);            items[numberOfItems] = menuItem;            numberOfItems = numberOfItems + 1;        }    }    @Override    public Iterator createIterator() {        // TODO Auto-generated method stub        return new FishIterator(items);    }}

类Client代码实现：

public class Client {    Menu fisMenu;    public Client(Menu fishMenu){        this.fisMenu = fishMenu;    }    public void printMenu(){        Iterator fishIterator = fisMenu.createIterator();        printMenu(fishIterator);    }    public void printMenu(Iterator iterator){        while (iterator.hasNext()) {            MenuItem menuItem = (MenuItem)iterator.next();            System.out.println(menuItem.getname());        }    }}

测试类MenuTest代码实现：

public class MenuTest {    public static void main(String[] args){        Menu fishMenu = new FishMenu();        Client client = new Client(fishMenu);        client.printMenu();    }}

执行结果：

烤鲫鱼烤草鱼烤大头鱼烤秋刀鱼烤鲨鱼

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