Update factory method

This commit is contained in:
Ilkka Seppälä
2021-06-13 18:35:13 +03:00
parent 588b106ada
commit 6feca5bd01
6 changed files with 41 additions and 39 deletions

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

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@ -44,4 +44,8 @@ public class ElfBlacksmith implements Blacksmith {
return ELFARSENAL.get(weaponType);
}
@Override
public String toString() {
return "The elf blacksmith";
}
}

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@ -37,6 +37,6 @@ public class ElfWeapon implements Weapon {
@Override
public String toString() {
return "Elven " + weaponType;
return "an elven " + weaponType;
}
}

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@ -43,4 +43,9 @@ public class OrcBlacksmith implements Blacksmith {
public Weapon manufactureWeapon(WeaponType weaponType) {
return ORCARSENAL.get(weaponType);
}
@Override
public String toString() {
return "The orc blacksmith";
}
}

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@ -37,6 +37,6 @@ public class OrcWeapon implements Weapon {
@Override
public String toString() {
return "Orcish " + weaponType;
return "an orcish " + weaponType;
}
}