Design Pattern-composite pattern iterator (iterator)

Detailed description of composite pattern iterator

Address: http://blog.csdn.net/caroline_wendy

Reference composite pattern: http://blog.csdn.net/caroline_wendy/article/details/36895627

Add the iterator function in composite pattern to traverse the items of each composite.

Specific Method:

1. Abstract component class (Abstract component) method for creating an iterator.

/*** @ Time July 4, 2014 */package composite; import Java. util. iterator;/*** @ author C. l. wang **/public abstract class menucomponent {public void add (menucomponent) {Throw new unsupportedoperationexception (); // if not provided, you cannot call} public void remove (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 ();}}

2. Composite iterator ).

/*** @ Time July 4, 2014 */package composite; import Java. util. iterator; import Java. util. stack;/*** @ author C. l. wang **/public class compositeiterator implements iterator <menucomponent> {stack <iterator <menucomponent> stack = new stack <iterator <menucomponent> (); /*****/Public compositeiterator (iterator <menucomponent> iterator) {// todo auto-generated constructor stubstack. push (iterator);} public bool EAN hasnext () {If (stack. empty () {return false;} else {iterator <menucomponent> iterator = (iterator <menucomponent>) stack. peek (); If (! Iterator. hasnext () {stack. pop (); Return hasnext (); // recursive call} else {return true ;}} public menucomponent next () {If (hasnext ()) {iterator <menucomponent> iterator = (iterator <menucomponent>) stack. peek (); menucomponent Component = (menucomponent) iterator. next (); If (Component instanceof menu) {stack. push (component. createiterator ();} return component;} else {return NULL;} public void remove () {Throw new unsupportedoperationexception ();}}

3. composite is used to create an iterator and composite iterator ).

/*** @ Time July 4, 2014 */package composite; import Java. util. arraylist; import Java. util. iterator;/*** @ author C. l. wang **/Public Class Menu extends menucomponent {arraylist <menucomponent> menucomponents = new arraylist <menucomponent> (); string name; string description; /*****/Public menu (string name, string description) {// todo auto-generated constructor stubthis. name = Name; this. description = description;} public void add (menucomponent) {menucomponents. add (menucomponent);} public void remove (menucomponent) {menucomponents. remove (menucomponent);} public menucomponent getchild (int I) {return (menucomponent) menucomponents. get (I) ;}public string getname () {return name;} Public String getdescription () {return description;} public void print () {system. out. print ("\ n" + getname (); system. out. println ("," + getdescription (); system. out. println ("--------------------"); iterator <menucomponent> iterator = menucomponents. iterator (); While (iterator. hasnext () {menucomponent = (menucomponent) iterator. next (); menucomponent. print () ;}} public iterator <menucomponent> createiterator () {return New compositeiterator (menucomponents. iterator ());}}

4. The leaf class (leaf) implements the method of creating an empty iterator (null iterator.

/*** @ Time July 4, 2014 */package composite; import Java. util. iterator;/*** @ author C. l. wang **/public class nulliterator implements iterator <menucomponent> {public menucomponent next () {return NULL;} public Boolean hasnext () {return false;} public void remove () {Throw new unsupportedoperationexception () ;}/ *** @ time July 4, 2014 */package composite; import Java. util. iterator;/*** @ author C. l. wang **/public class menuitem extends menucomponent {string name; string description; Boolean vegetarian; double price;/*****/Public menuitem (string name, string description, Boolean vegetarian, double price) {// todo auto-generated constructor stubthis. name = Name; this. description = description; this. vegetarian = vegetarian; this. price = price;} Public String getname () {return name;} Public String getdescription () {return description;} public double getprice () {return price;} public Boolean isvegetarian () {return vegetarian;} public void print () {system. out. print ("" + getname (); If (isvegetarian () {system. out. print ("(v)");} system. out. println ("," + getprice (); system. out. println ("--" + getdescription ();} public iterator <menucomponent> createiterator () {return New nulliterator ();}}

5. Customer class.

/*** @ Time July 4, 2014 */package composite; import Java. util. iterator;/*** @ author C. l. wang **/public class waitress {menucomponent allmenus;/*****/Public waitress (menucomponent allmenus) {// todo auto-generated constructor stubthis. allmenus = allmenus;} public void printmenu () {allmenus. print ();} public void printvegetarianmenu () {iterator <menucomponent> iterator = allmenus. createiterator (); system. out. println ("\ nvegetarian Menu \ n ----"); While (iterator. hasnext () {menucomponent = (menucomponent) iterator. next (); try {If (menucomponent. isvegetarian () menucomponent. print ();} catch (unsupportedoperationexception ex ){}}}}

6. Test class

/*** @ Time July 4, 2014 */package composite;/*** @ author C. l. wang **/public class menutestdrive {/*** @ Param ARGs */public static void main (string [] ARGs) {// todo auto-generated method stubmenucomponent pancakehousemenu = new menu ("Pancake House menu", "Breakfast"); menucomponent dinermenu = new menu ("Diner menu ", "lunch"); menucomponent cafemenu = new menu ("cafe menu", "dinner"); menucomponent Dess Ertmenu = new menu ("dessert menu", "dessert course! "); Menucomponent coffeemenu = new menu (" coffee menu "," stuff to go with your afternoon coffee "); menucomponent allmenus = new menu (" All Menus ", "All menus combined"); allmenus. add (pancakehousemenu); allmenus. add (dinermenu); allmenus. add (cafemenu); pancakehousemenu. add (New menuitem ("K & B's pancake breakfast", "pancakes with scrambled eggs, and toast", true, 2.99); pancakehousemenu. add (New menuitem ("regular pancake breakfast", "pancakes with fried eggs, sausage", false, 2.99); pancakehousemenu. add (New menuitem ("Blueberry Pancakes", "pancakes made with fresh blueberries, and blueberry syrup", true, 3.49); pancakehousemenu. add (New menuitem ("waffles", "waffles, with your choice of blueberries or strawberries", true, 3.59); dinermenu. add (New menuitem ("vegetarian BLT", "(fakin ') bacon with lettuce & tomato on whole wheat", true, 2.99); dinermenu. add (New menuitem ("BLT", "bacon with lettuce & tomato on whole wheat", false, 2.99); dinermenu. add (New menuitem ("soup of the day", "a bowl of the soup of the day, with a side of potato salad", false, 3.29); dinermenu. add (New menuitem ("hotdog", "a hot dog, with saurkraut, relish, onions, topped with cheese", false, 3.05); dinermenu. add (New menuitem ("steamed veggies and brown rice", "steamed vegetables over brown rice", true, 3.99); dinermenu. add (New menuitem ("Pasta", "spaghetti with marinara sauce, and a slice of sourdough bread", true, 3.89); dinermenu. add (dessertmenu); dessertmenu. add (New menuitem ("apple pie", "apple pie with a flakey crust, topped with vanilla icecream", true, 1.59); dessertmenu. add (New menuitem ("Cheesecake", "creamy New York cheesecake, with a chocolate Graham crust", true, 1.99); dessertmenu. add (New menuitem ("sorbet", "a scoop of raspberry and a scoop of Lime", true, 1.89); cafemenu. add (New menuitem ("Veggie burger and air fries", "Veggie burger on a whole wheat bun, lettuce, tomato, and fries", true, 3.99); cafemenu. add (New menuitem ("soup of the day", "a cup of the soup of the day, with a side salad", false, 3.69); cafemenu. add (New menuitem ("burrito", "a large burrito, with whole pinto beans, salsa, Guacamole", true, 4.29); cafemenu. add (coffeemenu); coffeemenu. add (New menuitem ("coffee cake", "crumbly cake topped with cinnamon and walnuts", true, 1.59); coffeemenu. add (New menuitem ("bagel", "flavors include sesame, poppyseed, cinnamon raisin, Pumpkin", false, 0.69); coffeemenu. add (New menuitem ("biscotti", "Three almond or hazelnut biscotti cookies", true, 0.89); waitress = new waitress (allmenus); waitress. printvegetarianmenu ();}}

7. output.

VEGETARIAN MENU---- K&B‘s Pancake Breakfast(v), 2.99    -- Pancakes with scrambled eggs, and toast Blueberry Pancakes(v), 3.49    -- Pancakes made with fresh blueberries, and blueberry syrup Waffles(v), 3.59    -- Waffles, with your choice of blueberries or strawberries Vegetarian BLT(v), 2.99    -- (Fakin‘) Bacon with lettuce & tomato on whole wheat Steamed Veggies and Brown Rice(v), 3.99    -- Steamed vegetables over brown rice Pasta(v), 3.89    -- Spaghetti with Marinara Sauce, and a slice of sourdough bread Apple Pie(v), 1.59    -- Apple pie with a flakey crust, topped with vanilla icecream Cheesecake(v), 1.99    -- Creamy New York cheesecake, with a chocolate graham crust Sorbet(v), 1.89    -- A scoop of raspberry and a scoop of lime Apple Pie(v), 1.59    -- Apple pie with a flakey crust, topped with vanilla icecream Cheesecake(v), 1.99    -- Creamy New York cheesecake, with a chocolate graham crust Sorbet(v), 1.89    -- A scoop of raspberry and a scoop of lime Veggie Burger and Air Fries(v), 3.99    -- Veggie burger on a whole wheat bun, lettuce, tomato, and fries Burrito(v), 4.29    -- A large burrito, with whole pinto beans, salsa, guacamole Coffee Cake(v), 1.59    -- Crumbly cake topped with cinnamon and walnuts Biscotti(v), 0.89    -- Three almond or hazelnut biscotti cookies Coffee Cake(v), 1.59    -- Crumbly cake topped with cinnamon and walnuts Biscotti(v), 0.89    -- Three almond or hazelnut biscotti cookies