Update factory method
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@ -21,7 +21,7 @@ Factory Method lets a class defer instantiation to subclasses.
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## Explanation
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## Explanation
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Real world example
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Real-world example
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> Blacksmith manufactures weapons. Elves require Elvish weapons and orcs require Orcish weapons.
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> Blacksmith manufactures weapons. Elves require Elvish weapons and orcs require Orcish weapons.
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> Depending on the customer at hand the right type of blacksmith is summoned.
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> Depending on the customer at hand the right type of blacksmith is summoned.
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@ -40,7 +40,7 @@ Wikipedia says
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**Programmatic Example**
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**Programmatic Example**
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Taking our blacksmith example above. First of all we have a `Blacksmith` interface and some
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Taking our blacksmith example above. First of all, we have a `Blacksmith` interface and some
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implementations for it:
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implementations for it:
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```java
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```java
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@ -65,15 +65,25 @@ When the customers come, the correct type of blacksmith is summoned and requeste
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manufactured:
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manufactured:
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```java
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```java
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var blacksmith = new ElfBlacksmith();
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Blacksmith blacksmith = new OrcBlacksmith();
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blacksmith.manufactureWeapon(WeaponType.SPEAR);
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Weapon weapon = blacksmith.manufactureWeapon(WeaponType.SPEAR);
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blacksmith.manufactureWeapon(WeaponType.AXE);
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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weapon = blacksmith.manufactureWeapon(WeaponType.AXE);
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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blacksmith = new ElfBlacksmith();
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weapon = blacksmith.manufactureWeapon(WeaponType.SPEAR);
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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weapon = blacksmith.manufactureWeapon(WeaponType.AXE);
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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```
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```
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Program output:
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Program output:
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```java
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```
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// Elven spear
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The orc blacksmith manufactured an orcish spear
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// Elven axe
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The orc blacksmith manufactured an orcish axe
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The elf blacksmith manufactured an elven spear
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The elf blacksmith manufactured an elven axe
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```
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```
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## Class diagram
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## Class diagram
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@ -89,7 +99,7 @@ Use the Factory Method pattern when:
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* Classes delegate responsibility to one of several helper subclasses, and you want to localize the
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* Classes delegate responsibility to one of several helper subclasses, and you want to localize the
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knowledge of which helper subclass is the delegate.
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knowledge of which helper subclass is the delegate.
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## Real world examples
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## Known uses
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* [java.util.Calendar](http://docs.oracle.com/javase/8/docs/api/java/util/Calendar.html#getInstance--)
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* [java.util.Calendar](http://docs.oracle.com/javase/8/docs/api/java/util/Calendar.html#getInstance--)
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* [java.util.ResourceBundle](http://docs.oracle.com/javase/8/docs/api/java/util/ResourceBundle.html#getBundle-java.lang.String-)
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* [java.util.ResourceBundle](http://docs.oracle.com/javase/8/docs/api/java/util/ResourceBundle.html#getBundle-java.lang.String-)
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@ -26,7 +26,7 @@ package com.iluwatar.factory.method;
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import lombok.extern.slf4j.Slf4j;
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import lombok.extern.slf4j.Slf4j;
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/**
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/**
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* The Factory Method is a creational design pattern which uses factory methods to deal with the
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* The Factory Method is a creational design pattern that uses factory methods to deal with the
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* problem of creating objects without specifying the exact class of object that will be created.
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* problem of creating objects without specifying the exact class of object that will be created.
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* This is done by creating objects via calling a factory method either specified in an interface
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* This is done by creating objects via calling a factory method either specified in an interface
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* and implemented by child classes, or implemented in a base class and optionally overridden by
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* and implemented by child classes, or implemented in a base class and optionally overridden by
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@ -41,39 +41,22 @@ import lombok.extern.slf4j.Slf4j;
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@Slf4j
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@Slf4j
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public class App {
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public class App {
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private final Blacksmith blacksmith;
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/**
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* Creates an instance of <code>App</code> which will use <code>blacksmith</code> to manufacture
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* the weapons for war.
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* <code>App</code> is unaware which concrete implementation of {@link Blacksmith} it is using.
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* The decision of which blacksmith implementation to use may depend on configuration, or
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* the type of rival in war.
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* @param blacksmith a non-null implementation of blacksmith
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*/
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public App(Blacksmith blacksmith) {
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this.blacksmith = blacksmith;
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}
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/**
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/**
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* Program entry point.
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* Program entry point.
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*
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* @param args command line args
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* @param args command line args
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*/
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*/
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public static void main(String[] args) {
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public static void main(String[] args) {
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// Lets go to war with Orc weapons
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var app = new App(new OrcBlacksmith());
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app.manufactureWeapons();
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// Lets go to war with Elf weapons
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Blacksmith blacksmith = new OrcBlacksmith();
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app = new App(new ElfBlacksmith());
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Weapon weapon = blacksmith.manufactureWeapon(WeaponType.SPEAR);
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app.manufactureWeapons();
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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}
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private void manufactureWeapons() {
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var weapon = blacksmith.manufactureWeapon(WeaponType.SPEAR);
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LOGGER.info(weapon.toString());
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weapon = blacksmith.manufactureWeapon(WeaponType.AXE);
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weapon = blacksmith.manufactureWeapon(WeaponType.AXE);
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LOGGER.info(weapon.toString());
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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blacksmith = new ElfBlacksmith();
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weapon = blacksmith.manufactureWeapon(WeaponType.SPEAR);
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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weapon = blacksmith.manufactureWeapon(WeaponType.AXE);
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LOGGER.info("{} manufactured {}", blacksmith, weapon);
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}
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}
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}
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}
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@ -44,4 +44,8 @@ public class ElfBlacksmith implements Blacksmith {
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return ELFARSENAL.get(weaponType);
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return ELFARSENAL.get(weaponType);
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}
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}
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@Override
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public String toString() {
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return "The elf blacksmith";
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}
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}
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}
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@ -37,6 +37,6 @@ public class ElfWeapon implements Weapon {
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@Override
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@Override
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public String toString() {
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public String toString() {
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return "Elven " + weaponType;
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return "an elven " + weaponType;
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}
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}
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}
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}
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@ -43,4 +43,9 @@ public class OrcBlacksmith implements Blacksmith {
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public Weapon manufactureWeapon(WeaponType weaponType) {
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public Weapon manufactureWeapon(WeaponType weaponType) {
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return ORCARSENAL.get(weaponType);
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return ORCARSENAL.get(weaponType);
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}
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}
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@Override
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public String toString() {
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return "The orc blacksmith";
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}
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}
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}
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@ -37,6 +37,6 @@ public class OrcWeapon implements Weapon {
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@Override
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@Override
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public String toString() {
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public String toString() {
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return "Orcish " + weaponType;
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return "an orcish " + weaponType;
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}
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}
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}
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}
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