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docs: update strategy

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Ilkka Seppälä
2024-05-27 13:08:56 +03:00
parent aed840d72c
commit 201675d7fc
1 changed files with 68 additions and 18 deletions
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strategy/README.md
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@@ -36,7 +36,7 @@ Wikipedia says
Slaying dragons is a dangerous job. With experience, it becomes easier. Veteran dragonslayers have developed different fighting strategies against different types of dragons.
Let's first introduce the dragon-slaying strategy interface and its implementations.
Let's first introduce the `DragonSlayingStrategy` interface and its implementations.
```java
@FunctionalInterface
@@ -44,7 +44,9 @@ public interface DragonSlayingStrategy {
void execute();
}
```
```java
@Slf4j
public class MeleeStrategy implements DragonSlayingStrategy {
@@ -53,7 +55,9 @@ public class MeleeStrategy implements DragonSlayingStrategy {
LOGGER.info("With your Excalibur you sever the dragon's head!");
}
}
```
```java
@Slf4j
public class ProjectileStrategy implements DragonSlayingStrategy {
@@ -62,7 +66,9 @@ public class ProjectileStrategy implements DragonSlayingStrategy {
LOGGER.info("You shoot the dragon with the magical crossbow and it falls dead on the ground!");
}
}
```
```java
@Slf4j
public class SpellStrategy implements DragonSlayingStrategy {
@@ -73,7 +79,7 @@ public class SpellStrategy implements DragonSlayingStrategy {
}
```
And here is the mighty dragonslayer, who can pick his fighting strategy based on the opponent.
And here is the mighty `DragonSlayer`, who can pick his fighting strategy based on the opponent.
```java
public class DragonSlayer {
@@ -94,35 +100,79 @@ public class DragonSlayer {
}
```
Finally, here's the dragonslayer in action.
Finally, here's the `DragonSlayer` in action.
```java
LOGGER.info("Green dragon spotted ahead!");
@Slf4j
public class App {
private static final String RED_DRAGON_EMERGES = "Red dragon emerges.";
private static final String GREEN_DRAGON_SPOTTED = "Green dragon spotted ahead!";
private static final String BLACK_DRAGON_LANDS = "Black dragon lands before you.";
public static void main(String[] args) {
// GoF Strategy pattern
LOGGER.info(GREEN_DRAGON_SPOTTED);
var dragonSlayer = new DragonSlayer(new MeleeStrategy());
dragonSlayer.goToBattle();
LOGGER.info("Red dragon emerges.");
LOGGER.info(RED_DRAGON_EMERGES);
dragonSlayer.changeStrategy(new ProjectileStrategy());
dragonSlayer.goToBattle();
LOGGER.info("Black dragon lands before you.");
LOGGER.info(BLACK_DRAGON_LANDS);
dragonSlayer.changeStrategy(new SpellStrategy());
dragonSlayer.goToBattle();
// Java 8 functional implementation Strategy pattern
LOGGER.info(GREEN_DRAGON_SPOTTED);
dragonSlayer = new DragonSlayer(
() -> LOGGER.info("With your Excalibur you severe the dragon's head!"));
dragonSlayer.goToBattle();
LOGGER.info(RED_DRAGON_EMERGES);
dragonSlayer.changeStrategy(() -> LOGGER.info(
"You shoot the dragon with the magical crossbow and it falls dead on the ground!"));
dragonSlayer.goToBattle();
LOGGER.info(BLACK_DRAGON_LANDS);
dragonSlayer.changeStrategy(() -> LOGGER.info(
"You cast the spell of disintegration and the dragon vaporizes in a pile of dust!"));
dragonSlayer.goToBattle();
// Java 8 lambda implementation with enum Strategy pattern
LOGGER.info(GREEN_DRAGON_SPOTTED);
dragonSlayer.changeStrategy(LambdaStrategy.Strategy.MELEE_STRATEGY);
dragonSlayer.goToBattle();
LOGGER.info(RED_DRAGON_EMERGES);
dragonSlayer.changeStrategy(LambdaStrategy.Strategy.PROJECTILE_STRATEGY);
dragonSlayer.goToBattle();
LOGGER.info(BLACK_DRAGON_LANDS);
dragonSlayer.changeStrategy(LambdaStrategy.Strategy.SPELL_STRATEGY);
dragonSlayer.goToBattle();
}
}
```
Program output:
```
Green dragon spotted ahead!
With your Excalibur you sever the dragon's head!
Red dragon emerges.
You shoot the dragon with the magical crossbow and it falls dead on the ground!
Black dragon lands before you.
You cast the spell of disintegration and the dragon vaporizes in a pile of dust!
13:06:36.631 [main] INFO com.iluwatar.strategy.App -- Green dragon spotted ahead!
13:06:36.634 [main] INFO com.iluwatar.strategy.MeleeStrategy -- With your Excalibur you sever the dragon's head!
13:06:36.634 [main] INFO com.iluwatar.strategy.App -- Red dragon emerges.
13:06:36.634 [main] INFO com.iluwatar.strategy.ProjectileStrategy -- You shoot the dragon with the magical crossbow and it falls dead on the ground!
13:06:36.634 [main] INFO com.iluwatar.strategy.App -- Black dragon lands before you.
13:06:36.634 [main] INFO com.iluwatar.strategy.SpellStrategy -- You cast the spell of disintegration and the dragon vaporizes in a pile of dust!
13:06:36.634 [main] INFO com.iluwatar.strategy.App -- Green dragon spotted ahead!
13:06:36.634 [main] INFO com.iluwatar.strategy.App -- With your Excalibur you severe the dragon's head!
13:06:36.634 [main] INFO com.iluwatar.strategy.App -- Red dragon emerges.
13:06:36.635 [main] INFO com.iluwatar.strategy.App -- You shoot the dragon with the magical crossbow and it falls dead on the ground!
13:06:36.635 [main] INFO com.iluwatar.strategy.App -- Black dragon lands before you.
13:06:36.635 [main] INFO com.iluwatar.strategy.App -- You cast the spell of disintegration and the dragon vaporizes in a pile of dust!
13:06:36.635 [main] INFO com.iluwatar.strategy.App -- Green dragon spotted ahead!
13:06:36.637 [main] INFO com.iluwatar.strategy.LambdaStrategy -- With your Excalibur you severe the dragon's head!
13:06:36.637 [main] INFO com.iluwatar.strategy.App -- Red dragon emerges.
13:06:36.637 [main] INFO com.iluwatar.strategy.LambdaStrategy -- You shoot the dragon with the magical crossbow and it falls dead on the ground!
13:06:36.637 [main] INFO com.iluwatar.strategy.App -- Black dragon lands before you.
13:06:36.637 [main] INFO com.iluwatar.strategy.LambdaStrategy -- You cast the spell of disintegration and the dragon vaporizes in a pile of dust!
```
## Class diagram
![Strategy](./etc/strategy_urm.png "Strategy")
## Applicability
Use the Strategy pattern when:
@@ -134,7 +184,7 @@ Use the Strategy pattern when:
## Tutorial
* [Strategy Pattern Tutorial - Digital Ocean](https://www.digitalocean.com/community/tutorials/strategy-design-pattern-in-java-example-tutorial)
* [Strategy Pattern Tutorial (DigitalOcean)](https://www.digitalocean.com/community/tutorials/strategy-design-pattern-in-java-example-tutorial)
## Known Uses
@@ -157,8 +207,8 @@ Trade-offs:
## Related patterns
* [State](https://java-design-patterns.com/patterns/state/): Similar in structure but used to represent state-dependent behavior rather than interchangeable algorithms.
* [Decorator](https://java-design-patterns.com/patterns/decorator/): Enhances an object without changing its interface but is more concerned with responsibilities than algorithms.
* [State](https://java-design-patterns.com/patterns/state/): Similar in structure but used to represent state-dependent behavior rather than interchangeable algorithms.
## Credits