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Added comments about object sharing in Flyweight example + some minor

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fixes.
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Ilkka Seppala
2015-05-31 21:10:19 +03:00
parent 2a9de6abcc
commit b952469a44
2 changed files with 80 additions and 77 deletions
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114
flyweight/src/main/java/com/iluwatar/flyweight/AlchemistShop.java
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@ -1,57 +1,57 @@
package com.iluwatar.flyweight; package com.iluwatar.flyweight;
import java.util.ArrayList; import java.util.ArrayList;
import java.util.List; import java.util.List;
/** /**
* *
* AlchemistShop holds potions on its shelves. * AlchemistShop holds potions on its shelves.
* It uses PotionFactory to provide the potions. * It uses PotionFactory to provide the potions.
* *
*/ */
public class AlchemistShop { public class AlchemistShop {
List<Potion> topShelf; private List<Potion> topShelf;
List<Potion> bottomShelf; private List<Potion> bottomShelf;
public AlchemistShop() { public AlchemistShop() {
topShelf = new ArrayList<>(); topShelf = new ArrayList<>();
bottomShelf = new ArrayList<>(); bottomShelf = new ArrayList<>();
fillShelves(); fillShelves();
} }
private void fillShelves() { private void fillShelves() {
PotionFactory factory = new PotionFactory(); PotionFactory factory = new PotionFactory();
topShelf.add(factory.createPotion(PotionType.INVISIBILITY)); topShelf.add(factory.createPotion(PotionType.INVISIBILITY));
topShelf.add(factory.createPotion(PotionType.INVISIBILITY)); topShelf.add(factory.createPotion(PotionType.INVISIBILITY));
topShelf.add(factory.createPotion(PotionType.STRENGTH)); topShelf.add(factory.createPotion(PotionType.STRENGTH));
topShelf.add(factory.createPotion(PotionType.HEALING)); topShelf.add(factory.createPotion(PotionType.HEALING));
topShelf.add(factory.createPotion(PotionType.INVISIBILITY)); topShelf.add(factory.createPotion(PotionType.INVISIBILITY));
topShelf.add(factory.createPotion(PotionType.STRENGTH)); topShelf.add(factory.createPotion(PotionType.STRENGTH));
topShelf.add(factory.createPotion(PotionType.HEALING)); topShelf.add(factory.createPotion(PotionType.HEALING));
topShelf.add(factory.createPotion(PotionType.HEALING)); topShelf.add(factory.createPotion(PotionType.HEALING));
bottomShelf.add(factory.createPotion(PotionType.POISON)); bottomShelf.add(factory.createPotion(PotionType.POISON));
bottomShelf.add(factory.createPotion(PotionType.POISON)); bottomShelf.add(factory.createPotion(PotionType.POISON));
bottomShelf.add(factory.createPotion(PotionType.POISON)); bottomShelf.add(factory.createPotion(PotionType.POISON));
bottomShelf.add(factory.createPotion(PotionType.HOLY_WATER)); bottomShelf.add(factory.createPotion(PotionType.HOLY_WATER));
bottomShelf.add(factory.createPotion(PotionType.HOLY_WATER)); bottomShelf.add(factory.createPotion(PotionType.HOLY_WATER));
} }
public void enumerate() { public void enumerate() {
System.out.println("Enumerating top shelf potions\n"); System.out.println("Enumerating top shelf potions\n");
for (Potion p : topShelf) { for (Potion p : topShelf) {
p.drink(); p.drink();
} }
System.out.println("\nEnumerating bottom shelf potions\n"); System.out.println("\nEnumerating bottom shelf potions\n");
for (Potion p : bottomShelf) { for (Potion p : bottomShelf) {
p.drink(); p.drink();
} }
} }
} }

43
flyweight/src/main/java/com/iluwatar/flyweight/App.java
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@ -1,20 +1,23 @@
package com.iluwatar.flyweight; package com.iluwatar.flyweight;
/** /**
* *
* Flyweight pattern is useful when the program needs a huge amount of objects. * Flyweight pattern is useful when the program needs a huge amount of objects.
* It provides means to decrease resource usage by sharing object instances. * It provides means to decrease resource usage by sharing object instances.
* *
* In this example AlchemistShop has great amount of potions on its shelves. * In this example AlchemistShop has great amount of potions on its shelves.
* To fill the shelves AlchemistShop uses PotionFactory (which represents * To fill the shelves AlchemistShop uses PotionFactory (which represents
* the Flyweight in this example). Internally PotionFactory holds a map * the Flyweight in this example). Internally PotionFactory holds a map
* of the potions and lazily creates new ones when requested. * of the potions and lazily creates new ones when requested.
* *
*/ * To enable safe sharing, between clients and threads, Flyweight objects must
public class App { * be immutable. Flyweight objects are by definition value objects.
*
public static void main(String[] args) { */
AlchemistShop alchemistShop = new AlchemistShop(); public class App {
alchemistShop.enumerate();
} public static void main(String[] args) {
} AlchemistShop alchemistShop = new AlchemistShop();
alchemistShop.enumerate();
}
}