Merge pull request #15690 from parthiv39731/PR-7319

BAEL-7388, Builder Pattern and Inheritance

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/inheritance/withgenerics/Car.java

@@ -0,0 +1,42 @@
+package com.baeldung.builder.inheritance.withgenerics;
+
+public class Car extends Vehicle {
+
+    private String make;
+    private String model;
+
+    public String getModel() {
+        return model;
+    }
+
+    public Car(Builder builder) {
+        super(builder);
+        this.make = builder.make;
+        this.model = builder.model;
+    }
+
+    public String getMake() {
+        return make;
+    }
+
+    public static class Builder<T extends Builder<T>> extends Vehicle.Builder<T> {
+
+        protected String make;
+        protected String model;
+
+        public T make(String make) {
+            this.make = make;
+            return self();
+        }
+
+        public T model(String model) {
+            this.model = model;
+            return self();
+        }
+
+        @Override
+        public Car build() {
+            return new Car(this);
+        }
+    }
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/inheritance/withgenerics/ElectricCar.java

@@ -0,0 +1,28 @@
+package com.baeldung.builder.inheritance.withgenerics;
+
+public class ElectricCar extends Car {
+    private String batteryType;
+
+    public String getBatteryType() {
+        return batteryType;
+    }
+
+    public ElectricCar(Builder builder) {
+        super(builder);
+        this.batteryType = builder.batteryType;
+    }
+
+    public static class Builder<T extends Builder<T>> extends Car.Builder<T> {
+        protected String batteryType;
+
+        public T batteryType(String batteryType) {
+            this.batteryType = batteryType;
+            return self();
+        }
+
+        @Override
+        public ElectricCar build() {
+            return new ElectricCar(this);
+        }
+    }
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/inheritance/withgenerics/Vehicle.java

@@ -0,0 +1,44 @@
+package com.baeldung.builder.inheritance.withgenerics;
+
+public class Vehicle {
+
+    private String colour;
+    private String fuelType;
+
+    public Vehicle(Builder builder) {
+        this.colour = builder.colour;
+        this.fuelType = builder.fuelType;
+    }
+
+    public String getColour() {
+        return colour;
+    }
+
+    public String getFuelType() {
+        return fuelType;
+    }
+
+    public static class Builder<T extends Builder> {
+
+        protected String colour;
+        protected String fuelType;
+
+        T self() {
+            return (T) this;
+        }
+
+        public T colour(String colour) {
+            this.colour = colour;
+            return self();
+        }
+
+        public T fuelType(String fuelType) {
+            this.fuelType = fuelType;
+            return self();
+        }
+
+        public Vehicle build() {
+            return new Vehicle(this);
+        }
+    }
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/inheritance/withoutgenerics/Car.java

@@ -0,0 +1,53 @@
+package com.baeldung.builder.inheritance.withoutgenerics;
+
+public class Car extends Vehicle {
+
+    private String make;
+    private String model;
+
+    public String getMake() {
+        return make;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    public Car(CarBuilder builder) {
+        super(builder);
+        this.make = builder.make;
+        this.model = builder.model;
+    }
+
+    public static class CarBuilder extends VehicleBuilder {
+
+        protected String make;
+        protected String model;
+
+        @Override
+        public CarBuilder colour(String colour) {
+            this.colour = colour;
+            return this;
+        }
+
+        @Override
+        public CarBuilder fuelType(String fuelType) {
+            this.fuelType = fuelType;
+            return this;
+        }
+
+        public CarBuilder make(String make) {
+            this.make = make;
+            return this;
+        }
+
+        public CarBuilder model(String model) {
+            this.model = model;
+            return this;
+        }
+
+        public Car build() {
+            return new Car(this);
+        }
+    }
+}

patterns-modules/design-patterns-creational-2/src/main/java/com/baeldung/builder/inheritance/withoutgenerics/Vehicle.java

@@ -0,0 +1,41 @@
+package com.baeldung.builder.inheritance.withoutgenerics;
+
+public class Vehicle {
+
+    private String fuelType;
+    private String colour;
+
+    public String getFuelType() {
+        return fuelType;
+    }
+
+    public String getColour() {
+        return colour;
+    }
+
+    public Vehicle(VehicleBuilder builder) {
+        this.colour = builder.colour;
+        this.fuelType = builder.fuelType;
+
+    }
+
+    public static class VehicleBuilder {
+
+        protected String fuelType;
+        protected String colour;
+
+        public VehicleBuilder fuelType(String fuelType) {
+            this.fuelType = fuelType;
+            return this;
+        }
+
+        public VehicleBuilder colour(String colour) {
+            this.colour = colour;
+            return this;
+        }
+
+        public Vehicle build() {
+            return new Vehicle(this);
+        }
+    }
+}

patterns-modules/design-patterns-creational-2/src/main/resources/builder-pattern.puml

@@ -0,0 +1,56 @@
+@startuml
+'https://plantuml.com/class-diagram
+'skinparam Handwritten true
+skinparam ClassBorderColor black/#63b175
+skinparam BackgroundColor #fdf8f6
+skinparam class {
+ ArrowColor #63b175
+}
+
+hide empty methods
+hide empty attributes
+
+class Vehicle {
+   +fuelType : String
+   +colour : String
+}
+
+class VehicleBuilder {
+    +fuelType : String
+    +colour : String
+    +build() : Vehicle
+    +fuelType(String fuelType) : VehicleBuilder
+    +colour(String colour) : VehicleBuilder
+}
+class Car {
+   +make : String
+   +model : String
+}
+class CarBuilder {
+   +make : String
+   +model : String
+   +build() : Car
+   +make(String make): CarBuilder
+   +model(String make): CarBuilder
+}
+
+class ElectricCar {
+   +batteryType : String
+
+}
+
+class ElectricCarBuilder {
+   +batteryType : String
+   +build() : ElectricCar
+   +batteryType(String batteryType): ElectricCarBuilder
+}
+CarBuilder -left-|> VehicleBuilder: extends
+ElectricCarBuilder -left-|> CarBuilder: extends
+VehicleBuilder -down-> Vehicle: builds
+CarBuilder -down-> Car:builds
+ElectricCarBuilder -down-> ElectricCar: builds
+
+Vehicle <|-right- Car: extends
+Car <|-right- ElectricCar: extends
+
+@enduml

patterns-modules/design-patterns-creational-2/src/test/java/com/baeldung/builder/inheritance/withoutgenerics/BuilderInheritanceUnitTest.java

@@ -0,0 +1,19 @@
+package com.baeldung.builder.inheritance.withoutgenerics;
+
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+public class BuilderInheritanceUnitTest {
+
+    @Test
+    void givenNonGenericImpl_whenBuild_thenReturnObject() {
+        Car car = new Car.CarBuilder().colour("red")
+            .fuelType("Petrol")
+            .make("Ford")
+            .model("F")
+            .build();
+        assertEquals("red", car.getColour());
+        assertEquals("Ford", car.getMake());
+    }
+
+}

patterns-modules/design-patterns-creational-2/src/test/java/com/baledung/builder/inheritance/withgenerics/BuilderInheritanceUnitTest.java

@@ -0,0 +1,36 @@
+package com.baledung.builder.inheritance.withgenerics;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.builder.inheritance.withgenerics.Car;
+import com.baeldung.builder.inheritance.withgenerics.ElectricCar;
+
+public class BuilderInheritanceUnitTest {
+
+    @Test
+    void givenGenericImpl_whenBuild_thenReturnObject() {
+        Car.Builder<?> carBuilder1 = new Car.Builder();
+        Car car = carBuilder1.colour("red")
+            .fuelType("Petrol")
+            .make("Ford")
+            .model("F")
+            .build();
+
+        ElectricCar.Builder<?> ElectricCarBuilder = new ElectricCar.Builder();
+        ElectricCar eCar = ElectricCarBuilder.make("Mercedes")
+            .colour("White")
+            .model("G")
+            .fuelType("Electric")
+            .batteryType("Lithium")
+            .build();
+
+        assertEquals("red", car.getColour());
+        assertEquals("Ford", car.getMake());
+
+        assertEquals("Electric", eCar.getFuelType());
+        assertEquals("Lithium", eCar.getBatteryType());
+    }
+
+}