Document the Design Patterns with improvements

.gitignore

@@ -2,5 +2,4 @@
 *.log
 
 # Compiled Files #
-bin/
 out/

README.md

@@ -1 +1,3 @@
-# design-patterns
+* ### Information Credits: [`refactoring.guru`](https://refactoring.guru/design-patterns)
+* ### Documentation Credits: [`java-design-patterns`](https://java-design-patterns.com/patterns/)
+* ### Video Credits: [`@ConceptAndCoding`](https://www.youtube.com/@ConceptandCoding)

design-patterns.iml

@@ -22,7 +22,7 @@
         <SOURCES>
           <root url="jar://$USER_HOME$/.ideaLibSources/lombok-1.18.34-sources.jar!/" />
         </SOURCES>
-      </library>ō
+      </library>
     </orderEntry>
   </component>
 </module>

src/course/README.md

@@ -0,0 +1,3 @@
+# Learning Design Patterns with Java
+
+### Coursera Course: https://www.coursera.org/learn/design-patterns

src/practice/README.md

@@ -0,0 +1,41 @@
+# Implementations of Design Patterns
+
+* ### Examples of [Creational](./creational) Design Patterns with Java:
+
+|              Design Pattern               |                                   Information                                   |                                     Documentation                                     |                                  Video                                  |
+|:-----------------------------------------:|:-------------------------------------------------------------------------------:|:-------------------------------------------------------------------------------------:|:-----------------------------------------------------------------------:|
+|  [Factory Method](./creational/factory)   |  [`refactoring.guru`](https://refactoring.guru/design-patterns/factory-method)  |  [`java-design-patterns`](https://java-design-patterns.com/patterns/factory-method/)  |                                                                         |
+| [Abstract Factory](./creational/notional) | [`refactoring.guru`](https://refactoring.guru/design-patterns/abstract-factory) | [`java-design-patterns`](https://java-design-patterns.com/patterns/abstract-factory/) |                                                                         |
+|      [Builder](./creational/builder)      |     [`refactoring.guru`](https://refactoring.guru/design-patterns/builder)      |     [`java-design-patterns`](https://java-design-patterns.com/patterns/builder/)      | [`@ConceptAndCoding`](https://youtu.be/qOLRxN5eVC0?si=E67H3Rx33vvzY4d_) |
+|     [Object Pool](./creational/pool)      |                                       N/A                                       |   [`java-design-patterns`](https://java-design-patterns.com/patterns/object-pool/)    | [`@ConceptAndCoding`](https://youtu.be/obmc24IHqew?si=q7M84QnN_sbFrku0) |
+|    [Prototype](./creational/prototype)    |    [`refactoring.guru`](https://refactoring.guru/design-patterns/prototype)     |    [`java-design-patterns`](https://java-design-patterns.com/patterns/prototype/)     |                                                                         |
+|    [Singleton](./creational/singleton)    |    [`refactoring.guru`](https://refactoring.guru/design-patterns/singleton)     |    [`java-design-patterns`](https://java-design-patterns.com/patterns/singleton/)     |                                                                         |
+
+* ### Examples of [Structural](./structural) Design Patterns with Java:
+
+|           Design Pattern            |                               Information                                |                                 Documentation                                  |                                  Video                                  |
+|:-----------------------------------:|:------------------------------------------------------------------------:|:------------------------------------------------------------------------------:|:-----------------------------------------------------------------------:|
+|   [Adapter](./structural/adapter)   |  [`refactoring.guru`](https://refactoring.guru/design-patterns/adapter)  |  [`java-design-patterns`](https://java-design-patterns.com/patterns/adapter/)  | [`@ConceptAndCoding`](https://youtu.be/8wrg7IsILhQ?si=PF2kgCqwYN35dgao) |
+|    [Bridge](./structural/bridge)    |  [`refactoring.guru`](https://refactoring.guru/design-patterns/bridge)   |  [`java-design-patterns`](https://java-design-patterns.com/patterns/bridge/)   | [`@ConceptAndCoding`](https://youtu.be/SOw1_W0taBg?si=4TxZSukUZCUYiNWj) |
+| [Composite](./structural/composite) | [`refactoring.guru`](https://refactoring.guru/design-patterns/composite) | [`java-design-patterns`](https://java-design-patterns.com/patterns/composite/) |                                                                         |
+| [Decorator](./structural/decorator) | [`refactoring.guru`](https://refactoring.guru/design-patterns/decorator) | [`java-design-patterns`](https://java-design-patterns.com/patterns/decorator/) | [`@ConceptAndCoding`](https://youtu.be/w6a9MXUwcfY?si=KW_bfuG6F35_blZZ) |
+|    [Facade](./structural/facade)    |  [`refactoring.guru`](https://refactoring.guru/design-patterns/facade)   |  [`java-design-patterns`](https://java-design-patterns.com/patterns/facade/)   | [`@ConceptAndCoding`](https://youtu.be/GYaBXK54eLo?si=aCmexb4t3izwlU9d) |
+| [Flyweight](./structural/flyweight) | [`refactoring.guru`](https://refactoring.guru/design-patterns/flyweight) | [`java-design-patterns`](https://java-design-patterns.com/patterns/flyweight/) |                                                                         |
+|     [Proxy](./structural/proxy)     |   [`refactoring.guru`](https://refactoring.guru/design-patterns/proxy)   |   [`java-design-patterns`](https://java-design-patterns.com/patterns/proxy/)   | [`@ConceptAndCoding`](https://youtu.be/9MxHKlVc6ZM?si=tJME00X4UJ4XJJtc) |
+
+* ### Examples of [Behavioral](./behavioral) Design Patterns with Java:
+
+|                Design Pattern                 |                                      Information                                       |                                        Documentation                                         |                                  Video                                  |
+|:---------------------------------------------:|:--------------------------------------------------------------------------------------:|:--------------------------------------------------------------------------------------------:|:-----------------------------------------------------------------------:|
+| [Chain of Responsibility](./behavioral/chain) | [`refactoring.guru`](https://refactoring.guru/design-patterns/chain-of-responsibility) | [`java-design-patterns`](https://java-design-patterns.com/patterns/chain-of-responsibility/) | [`@ConceptAndCoding`](https://youtu.be/gvIn5QBdGDk?si=30kOIX2x7Gx3MlqR) |
+|        [Command](./behavioral/command)        |         [`refactoring.guru`](https://refactoring.guru/design-patterns/command)         |         [`java-design-patterns`](https://java-design-patterns.com/patterns/command/)         | [`@ConceptAndCoding`](https://youtu.be/E1lce5CWhE0?si=X4HIR777Y9ddFjPS) |
+|                  Interpreter                  |                                          N/A                                           |       [`java-design-patterns`](https://java-design-patterns.com/patterns/interpreter/)       | [`@ConceptAndCoding`](https://youtu.be/fFlPm0pzQYI?si=4DuKSD2Qbt1NQFUE) |
+|       [Iterator](./behavioral/iterator)       |        [`refactoring.guru`](https://refactoring.guru/design-patterns/iterator)         |        [`java-design-patterns`](https://java-design-patterns.com/patterns/iterator/)         | [`@ConceptAndCoding`](https://youtu.be/X7shKHOaYtU?si=F7dk7AZjEOaHpLhv) |
+|       [Mediator](./behavioral/mediator)       |        [`refactoring.guru`](https://refactoring.guru/design-patterns/mediator)         |        [`java-design-patterns`](https://java-design-patterns.com/patterns/mediator/)         |                                                                         |
+|        [Memento](./behavioral/memento)        |         [`refactoring.guru`](https://refactoring.guru/design-patterns/memento)         |         [`java-design-patterns`](https://java-design-patterns.com/patterns/memento/)         | [`@ConceptAndCoding`](https://youtu.be/nTo7e2lpGZ4?si=9wsYjiNs3iG-g0ti) |
+|                  Null Object                  |                                          N/A                                           |       [`java-design-patterns`](https://java-design-patterns.com/patterns/null-object/)       | [`@ConceptAndCoding`](https://youtu.be/iDPhxhamuTo?si=oBsfb-mqRKq764c8) |
+|       [Observer](./behavioral/observer)       |        [`refactoring.guru`](https://refactoring.guru/design-patterns/observer)         |        [`java-design-patterns`](https://java-design-patterns.com/patterns/observer/)         | [`@ConceptAndCoding`](https://youtu.be/Ep9_Zcgst3U?si=Vq--dx8gSRqY7mrH) |
+|          [State](./behavioral/state)          |          [`refactoring.guru`](https://refactoring.guru/design-patterns/state)          |          [`java-design-patterns`](https://java-design-patterns.com/patterns/state/)          |                                                                         |
+|       [Strategy](./behavioral/strategy)       |        [`refactoring.guru`](https://refactoring.guru/design-patterns/strategy)         |        [`java-design-patterns`](https://java-design-patterns.com/patterns/strategy/)         | [`@ConceptAndCoding`](https://youtu.be/u8DttUrXtEw?si=LskxabetaZKy9gKA) |
+|   [Template Method](./behavioral/template)    |     [`refactoring.guru`](https://refactoring.guru/design-patterns/template-method)     |     [`java-design-patterns`](https://java-design-patterns.com/patterns/template-method/)     | [`@ConceptAndCoding`](https://youtu.be/kwy-G1DEm0M?si=yNZlZCuseVQaUCmT) |
+|        [Visitor](./behavioral/visitor)        |         [`refactoring.guru`](https://refactoring.guru/design-patterns/visitor)         |         [`java-design-patterns`](https://java-design-patterns.com/patterns/visitor/)         | [`@ConceptAndCoding`](https://youtu.be/pDsz-AuFO0g?si=11YASEg0NspKyykR) |

src/practice/behavioral/README.md

@@ -0,0 +1,5 @@
+# Examples of `Behavioral` Design Patterns with Java
+
+### Pluralsight Course: https://www.pluralsight.com/courses/design-patterns-java-behavioral
+
+### YouTube Recap Video: https://youtu.be/DBDnUkTobaE?si=-bXWvLOWm9G9moRa

src/practice/behavioral/chain/Worker.java

@@ -1,11 +1,13 @@
 package practice.behavioral.chain;
 
+import lombok.EqualsAndHashCode;
 import lombok.NonNull;
 import lombok.Setter;
 import lombok.extern.java.Log;
 
 @Log
 @Setter
+@EqualsAndHashCode
 public abstract sealed class Worker permits General, Jailer, King, Officer {
 
   protected Worker next; // Worker who is NEXT in CHAIN of Responsibility

src/practice/behavioral/command/SwitchButton.java

@@ -21,7 +21,7 @@ public void toggleState() {
   }
 
   public void printState() {
-    var isOn = state ? "ON" : "OFF"; // Determine current state of Switch
+    var isOn = state ? "ON" : "OFF"; // Determine CURRENT state of Switch
     log.info("State of <" + location + "> Switch => [" + isOn + "]");
   }
 }

src/practice/behavioral/observer/Subject.java

@@ -8,5 +8,5 @@ public sealed interface Subject permits Weather {
 
   void detach(@NonNull final Observer watcher);
 
-  void notifyObservers();
+  void notifyObservers(); // UPDATE Observers
 }

src/practice/behavioral/observer/Weather.java

@@ -17,13 +17,13 @@ public final class Weather implements Subject {
 
   @Override
   public void attach(@NonNull final Observer watcher) {
-    log.info("Attaching Observer => [" + watcher + "]");
+    log.info("ATTACHING Observer => [" + watcher + "]");
     observers.add(watcher); // Add OBSERVER to current LIST
   }
 
   @Override
   public void detach(@NonNull final Observer watcher) {
-    log.info("Detaching Observer => [" + watcher + "]");
+    log.info("DETACHING Observer => [" + watcher + "]");
     observers.remove(watcher); // Remove OBSERVER from LIST
   }
 
@@ -34,9 +34,9 @@ public void notifyObservers() {
   }
 
   public void advanceTime() {
-    log.info("Current Weather Type => [" + currentWeatherType + "]");
+    log.info("CURRENT Weather TYPE => [" + currentWeatherType + "]");
     currentWeatherType = getFreshWeatherType(WeatherType.values());
-    log.info("Changed Weather Type => [" + currentWeatherType + "]");
+    log.info("CHANGED Weather TYPE => [" + currentWeatherType + "]");
     notifyObservers(); // Update ALL Watchers of CHANGE in Weather
   }
 

src/practice/behavioral/state/HasCoinState.java

@@ -17,13 +17,13 @@ public void insertCoin(@NonNull final VendorMachine machine) {
 
   @Override
   public void ejectCoin(@NonNull final VendorMachine machine) {
-    machine.setState(new NoCoinState()); // ALTER State afterwards
+    machine.setState(new NoCoinState()); // ALTER state afterwards
     log.info("PASSED in EJECTING Coin => [" + machine + "]");
   }
 
   @Override
   public void dispenseFood(@NonNull final VendorMachine machine) {
-    machine.setState(new NoCoinState()); // ALTER State AFTER Action
+    machine.setState(new NoCoinState()); // ALTER state after action
     log.info("PASSED in DISPENSING Food => [" + machine + "]");
   }
 }

src/practice/behavioral/state/NoCoinState.java

@@ -12,7 +12,7 @@ public final class NoCoinState implements VendorState {
 
   @Override
   public void insertCoin(@NonNull final VendorMachine machine) {
-    machine.setState(new HasCoinState()); // ALTER State afterwards
+    machine.setState(new HasCoinState()); // ALTER state afterwards
     log.info("PASSED in INSERTING Coin => [" + machine + "]");
   }
 

src/practice/behavioral/state/VendorMachine.java

@@ -15,12 +15,12 @@ public final class VendorMachine {
 
   public void insertMoney() {
     log.info("ATTEMPT to INSERT Money => [" + this + "]");
-    state.insertCoin(this); // Try to INSERT Money
+    state.insertCoin(this); // Attempt to INSERT Money
   }
 
   public void ejectMoney() {
     log.info("ATTEMPT to EJECT Money => [" + this + "]");
-    state.ejectCoin(this); // Try to EJECT Money
+    state.ejectCoin(this); // Attempt to EJECT Money
   }
 
   public void dispenseFood() {

src/practice/behavioral/strategy/PaymentGateway.java

@@ -16,7 +16,7 @@ public final class PaymentGateway {
   private PaymentStrategy strategy;
 
   public void checkout(@NonNull final int amount) {
-    log.info("SELECTED Strategy => " + strategy);
-    strategy.pay(amount); // EXECUTE specific Strategy
+    log.info("SELECTED Strategy => [" + strategy + "]");
+    strategy.pay(amount); // EXECUTE this SELECTED Strategy
   }
 }

src/practice/behavioral/strategy/StrategyDemo.java

@@ -7,7 +7,7 @@ public final class StrategyDemo {
 
   public static void main(final String... arguments) {
 
-    final var gateway = new PaymentGateway();
+    final var gateway = new PaymentGateway(); // SAME Gateway
 
     gateway.setStrategy(new CashPayment("wallet"));
     gateway.checkout(1_000); // Make PAYMENT with CASH

src/practice/behavioral/visitor/Captain.java

@@ -6,7 +6,7 @@
 @ToString
 public final class Captain extends ArmyUnit {
 
-  Captain(@NonNull final ArmyUnit... children) {
+  public Captain(@NonNull final ArmyUnit... children) {
     super(children);
   }
 

src/practice/behavioral/visitor/Recruit.java

@@ -6,7 +6,7 @@
 @ToString
 public final class Recruit extends ArmyUnit {
 
-  Recruit(@NonNull final ArmyUnit... children) {
+  public Recruit(@NonNull final ArmyUnit... children) {
     super(children);
   }
 

src/practice/behavioral/visitor/Sergeant.java

@@ -6,7 +6,7 @@
 @ToString
 public final class Sergeant extends ArmyUnit {
 
-  Sergeant(@NonNull final ArmyUnit... children) {
+  public Sergeant(@NonNull final ArmyUnit... children) {
     super(children);
   }
 

src/practice/behavioral/visitor/VisitorDemo.java

@@ -10,7 +10,7 @@ public static void main(final String[] arguments) {
     final var soldier = new Captain(
         new Sergeant(new Recruit(), new Recruit()),
         new Sergeant(new Recruit(), new Recruit())
-    ); // Create CAMP Hierarchy of Soldiers
+    ); // Create Army CAMP hierarchy of Soldiers
 
     soldier.accept(new RecruitFriend());
     soldier.accept(new SergeantFriend());

src/practice/creational/README.md

@@ -0,0 +1,5 @@
+# Examples of `Creational` Design Patterns with Java
+
+### Pluralsight Course: https://www.pluralsight.com/courses/java-se-17-creational-design-patterns
+
+### YouTube Recap Video: https://youtu.be/OuNOyFg942M?si=AykaiZsmEG7qHfhx

src/practice/creational/builder/BuilderDemo.java

@@ -1,9 +1,6 @@
 package practice.creational.builder;
 
 import practice.creational.builder.CustomPizza.PizzaChef;
-import practice.creational.builder.PizzaElement.DoughType;
-import practice.creational.builder.PizzaElement.SauceType;
-import practice.creational.builder.PizzaElement.ToppingType;
 
 /**
  * Example of Builder Design Pattern
@@ -12,10 +9,10 @@ public final class BuilderDemo {
 
   public static void main(final String... arguments) {
 
-    new PizzaChef(DoughType.BAKED).setSauceType(SauceType.HOT)
-        .setTopping(ToppingType.CAPSICUM_MUSHROOM).cookPizza().eatPizza();
+    new PizzaChef(PizzaElement.DoughType.BAKED).setSauceType(PizzaElement.SauceType.HOT)
+        .setTopping(PizzaElement.ToppingType.CAPSICUM_MUSHROOM).cookPizza().eatPizza();
 
-    new PizzaChef(DoughType.CROSS).setSauceType(SauceType.MILD)
-        .setTopping(ToppingType.CHEESE_CORN_TOMATO).cookPizza().eatPizza();
+    new PizzaChef(PizzaElement.DoughType.CROSS).setSauceType(PizzaElement.SauceType.MILD)
+        .setTopping(PizzaElement.ToppingType.CHEESE_CORN_TOMATO).cookPizza().eatPizza();
   }
 }

src/practice/creational/builder/CustomPizza.java

@@ -23,7 +23,7 @@ public final class CustomPizza {
   private final PizzaElement.ToppingType topping;
 
   public void eatPizza() {
-    log.info("EATING Pizza => " + this);
+    log.info("EATING the Pizza => [" + this + "]");
   }
 
   @Setter
@@ -40,7 +40,7 @@ protected static final class PizzaChef {
     private PizzaElement.ToppingType topping;
 
     public CustomPizza cookPizza() {
-      log.info("COOKING Pizza => " + this); // In OVEN
+      log.info("COOKING the Pizza => [" + this + "]");
       return new CustomPizza(doughType, sauceType, topping);
     }
   }

src/practice/creational/pool/PoolDemo.java

@@ -31,7 +31,7 @@ public static void main(final String[] arguments) {
 
     objectPool.status(); // CURRENT status
 
-    objectPool.remit(personObj3); // REMIT
-    objectPool.status(); // CURRENT status
+    objectPool.remit(personObj3); // BACK
+    objectPool.status(); // FINALE status
   }
 }

src/practice/structural/README.md

@@ -0,0 +1,5 @@
+# Examples of `Structural` Design Patterns with Java
+
+### Pluralsight Course: https://www.pluralsight.com/courses/design-patterns-java-structural
+
+### YouTube Recap Video: https://youtu.be/WxGtmIBZszk?si=GUdKyp6vGiS4g94Q

src/practice/structural/composite/HeadDepartment.java

@@ -20,16 +20,16 @@ public final class HeadDepartment implements Department {
   @NonNull
   private final String name;
 
-  public void addDepartment(Department department) {
-    departments.add(department);
+  public void addDepartment(@NonNull final Department department) {
+    departments.add(department); // ADD any SINGLE element in list
   }
 
-  public void addDepartments(Department... departments) {
-    this.departments.addAll(List.of(departments));
+  public void addDepartments(@NonNull final Department... departments) {
+    this.departments.addAll(List.of(departments)); // ADD multiple items
   }
 
-  public void removeDepartment(Department department) {
-    departments.remove(department);
+  public void removeDepartment(@NonNull final Department department) {
+    departments.remove(department); // REMOVE any particular element
   }
 
   @Override