Head First设计模式-迭代器模式
一、整体代码 Iterator.java
[java]
public inte易做图ce Iterator {
boolean hasNext();
Object next();
}
DinerMenuIterator.java
[java]
public class DinerMenuIterator implements Iterator {
MenuItem[] items;
int position = 0;
public DinerMenuIterator(MenuItem[] items) {
this.items = items;
}
public Object next() {
MenuItem menuItem = items[position];
position = position + 1;
return menuItem;
}
public boolean hasNext() {
if (position >= items.length || items[position] == null) {
return false;
} else {
return true;
}
}
}
PancakeHouseMenuIterator.java
[java]
import java.util.ArrayList;
public class PancakeHouseMenuIterator implements Iterator {
private ArrayList items;
private int position = 0;
public PancakeHouseMenuIterator(ArrayList items) {
this.items = items;
}
public Object next() {
Object object = items.get(position);
position = position + 1;
return object;
}
public boolean hasNext() {
if (position >= items.size()) {
return false;
} else {
return true;
}
}
}
DinerMenu.java
[java]
public class DinerMenu {
private static final int MAX_ITEMS = 6;
private int numberOfItems = 0;
private MenuItem[] menuItems;
public DinerMenu() {
menuItems = new MenuItem[MAX_ITEMS];
addItem("Vegetarian BLT",
"(Fakin') Bacon with lettuce & tomato on whole wheat", true, 2.99);
addItem("BLT",
"Bacon with lettuce & tomato on whole wheat", false, 2.99);
addItem("Soup of the day",
"Soup of the day, with a side of potato salad", false, 3.29);
addItem("Hotdog",
"A hot dog, with saurkraut, relish, onions, topped with cheese",
false, 3.05);
addItem("Steamed Veggies and Brown Rice",
"Steamed vegetables over brown rice", true, 3.99);
addItem("Pasta",
"Spaghetti with Marinara Sauce, and a slice of sourdough bread",
true, 3.89);
}
public void addItem(String name, String description,
boolean vegetarian, double price)
{
MenuItem menuItem = new MenuItem(name, description, vegetarian, price);
if (numberOfItems >= MAX_ITEMS) {
System.err.println("Sorry, menu is full! Can't add item to menu");
} else {
menuItems[numberOfItems] = menuItem;
numberOfItems = numberOfItems + 1;
}
}
public Iterator createIterator() {
return new DinerMenuIterator(menuItems);
}
// other menu methods here
}
PancakeHouseMenu.java
[java]
import java.util.ArrayList;
public class PancakeHouseMenu {
private ArrayList menuItems;
public PancakeHouseMenu() {
menuItems = new ArrayList();
addItem("K&B's Pancake Breakfast",
"Pancakes with scrambled eggs, and toast",
true,
2.99);
addItem("Regular Pancake Breakfast",
"Pancakes with fried eggs, sausage",
false,
2.99);
addItem("Blueberry Pancakes",
"Pancakes made with fresh blueberries",
true,
3.49);
addItem("Waffles",
"Waffles, with your choice of blue
补充：软件开发 , Java ,上一个：设计模式——门面模式
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