组合迭代器
package menu;import java.util.ArrayList;import java.util.Iterator;public class Menu extends MenuComponent {ArrayList<MenuComponent> menuComponents=new ArrayList<MenuComponent>();String name;String description;public Menu(String name,String description){this.name=name;this.description=description;}@Overridepublic void add(MenuComponent menuComponent) {menuComponents.add(menuComponent);}@Overridepublic void remove(MenuComponent menuComponent) {menuComponents.remove(menuComponent);}@Overridepublic MenuComponent getChild(int i) {return menuComponents.get(i);}@Overridepublic void print() {System.out.print("\n"+name);System.out.println(", "+description);System.out.println("----------------------");Iterator<MenuComponent> iterator=menuComponents.iterator();while(iterator.hasNext()){MenuComponent component=iterator.next();component.print();}}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}@Overridepublic Iterator<MenuComponent> createIterator() {return menuComponents.iterator();}}?package menu;import java.util.Iterator;public abstract class MenuComponent {public void add(MenuComponent menuComponent){throw new UnsupportedOperationException();}public void remove(MenuComponent menuComponent){throw new UnsupportedOperationException();}public MenuComponent getChild(int i){throw new UnsupportedOperationException();}public String getName(){throw new UnsupportedOperationException();}public String getDescription(){throw new UnsupportedOperationException();}public double getPrice(){throw new UnsupportedOperationException();}public boolean isVegetarian(){throw new UnsupportedOperationException();}public void print(){throw new UnsupportedOperationException();}public Iterator<MenuComponent> createIterator(){throw new UnsupportedOperationException();}}?
package menu;public class MenuItem extends MenuComponent {String name;String description;boolean vegetarian;double price;public MenuItem(String name,String description,boolean vegetarian,double price) {this.name=name;this.description=description;this.vegetarian=vegetarian;this.price=price;}@Overridepublic String getName() {return name;}public void setName(String name) {this.name = name;}@Overridepublic String getDescription() {return description;}public void setDescription(String description) {this.description = description;}@Overridepublic boolean isVegetarian() {return vegetarian;}public void setVegetarian(boolean vegetarian) {this.vegetarian = vegetarian;}@Overridepublic double getPrice() {return price;}public void setPrice(double price) {this.price = price;}@Overridepublic void print() { System.out.print(" "+getName()); if(isVegetarian()){ System.out.println("(v)"); } System.out.println(", "+getPrice()); System.out.println(" -- "+getDescription());}}?
package iterator;import java.util.Iterator;import java.util.Stack;import menu.Menu;import menu.MenuComponent;public class CompositeIterator implements Iterator<MenuComponent>{Stack<Iterator<MenuComponent>> stack=new Stack<Iterator<MenuComponent>>();public CompositeIterator(Iterator<MenuComponent> iterator) {stack.push(iterator);}@Overridepublic boolean hasNext() {if(stack.isEmpty()){return false;}else{Iterator<MenuComponent> iterator=stack.peek();//取栈顶if(!iterator.hasNext()){//如果没有下个元素，就将其出栈stack.pop();return hasNext();}else{return true;}}}@Overridepublic MenuComponent next() {if(hasNext()){Iterator<MenuComponent> iterator=stack.peek();MenuComponent menuComponent=iterator.next();if(menuComponent instanceof Menu){//如果不是叶结点就将当前节点入栈stack.push(menuComponent.createIterator());}return menuComponent;}else{return null;}}@Overridepublic void remove() {throw new UnsupportedOperationException();}}?