Implement the Structural Design Patterns (#5)

* Implement the Adapter Design Pattern

* Implement the Bridge Design Pattern

* Implement the Composite Design Pattern

* Implement the Decorator Design Pattern

* Implement the Facade Design Pattern

* Implement the Flyweight Design Pattern

* Implement the Proxy Design Pattern

Author: subhatav

src/practice/structural/adapter/AdapterDemo.java

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+package practice.structural.adapter;
+
+/**
+ * Example of Adapter Design Pattern
+ */
+public final class AdapterDemo {
+
+  public static void main(final String... arguments) {
+
+    new Olympian(new BoatAdapter()).rowBoat(); // Play
+  }
+}

src/practice/structural/adapter/BoatAdapter.java

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+package practice.structural.adapter;
+
+import lombok.EqualsAndHashCode;
+import lombok.ToString;
+
+@ToString
+@EqualsAndHashCode
+public final class BoatAdapter implements RowingBoat {
+
+  private final FishingBoat boat = new FishingBoat();
+
+  @Override
+  public void row() {
+    boat.sail();
+  }
+}

src/practice/structural/adapter/FishingBoat.java

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+package practice.structural.adapter;
+
+import lombok.EqualsAndHashCode;
+import lombok.extern.java.Log;
+
+@Log
+@EqualsAndHashCode
+public final class FishingBoat {
+
+  public void sail() {
+    log.info("Sailing BOAT => [" + this + "]");
+  }
+}

src/practice/structural/adapter/Olympian.java

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+package practice.structural.adapter;
+
+import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.java.Log;
+
+@Log
+@EqualsAndHashCode
+@RequiredArgsConstructor
+public final class Olympian {
+
+  @NonNull
+  private final RowingBoat boat;
+
+  public void rowBoat() {
+    log.info("ATHLETE in Rowing => [" + this + "]");
+    boat.row(); // ROW currently AVAILABLE type of BOAT
+  }
+}

src/practice/structural/adapter/RowingBoat.java

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+package practice.structural.adapter;
+
+public sealed interface RowingBoat permits BoatAdapter {
+
+  void row(); // Implementation of TECHNIQUES of ROWING
+}

src/practice/structural/bridge/BleedEffect.java

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+package practice.structural.bridge;
+
+import lombok.EqualsAndHashCode;
+import lombok.ToString;
+import lombok.extern.java.Log;
+
+@Log
+@EqualsAndHashCode
+@ToString(callSuper = true)
+public final class BleedEffect implements Enchantment {
+
+  @Override
+  public void activate() {
+    log.info("ACTIVATED Enchantment => [" + this + "]");
+  }
+
+  @Override
+  public void apply() {
+    log.info("APPLIED Enchantment => [" + this + "]");
+  }
+
+  @Override
+  public void deactivate() {
+    log.info("DEACTIVATED Enchantment => [" + this + "]");
+  }
+}

src/practice/structural/bridge/BridgeDemo.java

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+package practice.structural.bridge;
+
+/**
+ * Example of Bridge Design Pattern
+ */
+public final class BridgeDemo {
+
+  public static void main(final String... arguments) {
+
+    final var specialDagger = new Dagger(new PoisonEffect());
+
+    specialDagger.wield(); // WIELD `Dagger` with `PoisonEffect`
+    specialDagger.use(); // USING `Dagger` with `PoisonEffect`
+    specialDagger.sheath(); // SHEATH `Dagger` with `PoisonEffect`
+
+    final var specialHammer = new Hammer(new BleedEffect());
+
+    specialHammer.wield(); // WIELD `Hammer` with `BleedEffect`
+    specialHammer.use(); // USING `Hammer` with `BleedEffect`
+    specialHammer.sheath(); // SHEATH `Hammer` with `BleedEffect`
+  }
+}

src/practice/structural/bridge/Dagger.java

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+package practice.structural.bridge;
+
+import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+import lombok.extern.java.Log;
+
+@Log
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor
+public final class Dagger implements Weaponry {
+
+  @NonNull
+  private final Enchantment enchantment;
+
+  @Override
+  public void wield() {
+    log.info("WIELDED Weapon => [" + this + "]");
+    enchantment.activate(); // ACTIVATE current Spell
+  }
+
+  @Override
+  public void use() {
+    log.info("USING Weapon => [" + this + "]");
+    enchantment.apply(); // CAST this current Spell
+  }
+
+  @Override
+  public void sheath() {
+    log.info("SHEATHED Weapon => [" + this + "]");
+    enchantment.deactivate(); // DEACTIVATE this Spell
+  }
+}

src/practice/structural/bridge/Enchantment.java

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+package practice.structural.bridge;
+
+public sealed interface Enchantment permits BleedEffect, PoisonEffect {
+
+  void activate(); // Abstraction of ACTIVATING Enchantment
+
+  void apply(); // Abstraction of APPLYING Enchantment
+
+  void deactivate(); // Abstraction of DEACTIVATING Enchantment
+}

src/practice/structural/bridge/Hammer.java

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+package practice.structural.bridge;
+
+import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+import lombok.extern.java.Log;
+
+@Log
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor
+public final class Hammer implements Weaponry {
+
+  @NonNull
+  private final Enchantment enchantment;
+
+  @Override
+  public void wield() {
+    log.info("WIELDED Weapon => [" + this + "]");
+    enchantment.activate(); // ACTIVATE current Spell
+  }
+
+  @Override
+  public void use() {
+    log.info("USING Weapon => [" + this + "]");
+    enchantment.apply(); // CAST this current Spell
+  }
+
+  @Override
+  public void sheath() {
+    log.info("SHEATHED Weapon => [" + this + "]");
+    enchantment.deactivate(); // DEACTIVATE this Spell
+  }
+}

src/practice/structural/bridge/PoisonEffect.java

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+package practice.structural.bridge;
+
+import lombok.EqualsAndHashCode;
+import lombok.ToString;
+import lombok.extern.java.Log;
+
+@Log
+@EqualsAndHashCode
+@ToString(callSuper = true)
+public final class PoisonEffect implements Enchantment {
+
+  @Override
+  public void activate() {
+    log.info("ACTIVATED Enchantment => [" + this + "]");
+  }
+
+  @Override
+  public void apply() {
+    log.info("APPLIED Enchantment => [" + this + "]");
+  }
+
+  @Override
+  public void deactivate() {
+    log.info("DEACTIVATED Enchantment => [" + this + "]");
+  }
+}

src/practice/structural/bridge/Weaponry.java

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+package practice.structural.bridge;
+
+public sealed interface Weaponry permits Dagger, Hammer {
+
+  void wield(); // Abstraction of WIELDING Weaponry
+
+  void use(); // Abstraction of USING Weaponry
+
+  void sheath(); // Abstraction of SHEATHING Weaponry
+}

src/practice/structural/composite/CompositeDemo.java

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+package practice.structural.composite;
+
+/**
+ * Example of Composite Design Pattern
+ */
+public final class CompositeDemo {
+
+  public static void main(final String... arguments) {
+
+    final var headDepartment1 = new HeadDepartment("HR");
+    final var headDepartment2 = new HeadDepartment("IT");
+
+    final var headDepartment3 = new HeadDepartment("Company");
+
+    headDepartment1.addDepartment(new LeafDepartment("Relations"));
+    headDepartment1.addDepartment(new LeafDepartment("Accounts"));
+
+    headDepartment2.addDepartment(new LeafDepartment("Research"));
+    headDepartment2.addDepartment(new LeafDepartment("Testing"));
+
+    headDepartment3.addDepartments(headDepartment1, headDepartment2);
+
+    headDepartment3.printDepartmentName(); // Prints TOTAL Hierarchy
+  }
+}

src/practice/structural/composite/Department.java

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+package practice.structural.composite;
+
+public sealed interface Department permits HeadDepartment, LeafDepartment {
+
+  void printDepartmentName(); // PRINTS name of VARIOUS types of Department
+}

src/practice/structural/composite/HeadDepartment.java

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+package practice.structural.composite;
+
+import java.util.ArrayList;
+import java.util.List;
+import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+import lombok.extern.java.Log;
+
+@Log
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor
+public final class HeadDepartment implements Department {
+
+  @ToString.Exclude
+  private final List<Department> departments = new ArrayList<>();
+
+  @NonNull
+  private final String name;
+
+  public void addDepartment(Department department) {
+    departments.add(department);
+  }
+
+  public void addDepartments(Department... departments) {
+    this.departments.addAll(List.of(departments));
+  }
+
+  public void removeDepartment(Department department) {
+    departments.remove(department);
+  }
+
+  @Override
+  public void printDepartmentName() {
+    log.info("NAME of Department => [" + this + "]");
+    departments.forEach(Department::printDepartmentName);
+  }
+}

src/practice/structural/composite/LeafDepartment.java

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+package practice.structural.composite;
+
+import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+import lombok.extern.java.Log;
+
+@Log
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor
+public final class LeafDepartment implements Department {
+
+  @NonNull
+  private final String name;
+
+  @Override
+  public void printDepartmentName() {
+    log.info("NAME of Department => [" + this + "]");
+  }
+}

src/practice/structural/decorator/ChickenTaco.java

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+package practice.structural.decorator;
+
+import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.ToString;
+
+@ToString(callSuper = true)
+@EqualsAndHashCode(callSuper = true)
+public final class ChickenTaco extends TacoDecorator {
+
+  private static final Float MULTIPLIER = 1.35F;
+
+  public ChickenTaco(@NonNull final TacoRecipe taco) {
+    super(taco);
+  }
+
+  @Override
+  public float getCost() {
+    return taco.getCost() * MULTIPLIER;
+  }
+}

src/practice/structural/decorator/DecoratorDemo.java

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+package practice.structural.decorator;
+
+/**
+ * Example of Decorator Design Pattern
+ */
+public final class DecoratorDemo {
+
+  public static void main(final String... arguments) {
+
+    final var plainTaco = new PlainTaco();
+    plainTaco.printCost(); // Cook PLAIN
+
+    final var friedTaco = new FriedTaco(plainTaco);
+    friedTaco.printCost(); // Decorate FRIED Taco
+
+    final var chickenTaco = new ChickenTaco(friedTaco);
+    chickenTaco.printCost(); // Decorate CHICKEN Taco
+  }
+}