1

src/main/java/core/basesyntax/Car.java

@@ -1,25 +1,94 @@
 package core.basesyntax;
 
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 
-/**
- * Make this class immutable. See requirements in task description.
- */
-public class Car {
-    private int year;
-    private String color;
-    private List<Wheel> wheels;
-    private Engine engine;
+public final class Car {
+    private final int year;
+    private final String color;
+    private final List<Wheel> wheels;
+    private final Engine engine;
 
-    //implement this class
+    // constructor with deep copy
+    public Car(int year, String color, List<Wheel> wheels, Engine engine) {
+        this.year = year;
+        this.color = color;
+
+        // deep copy of list
+        this.wheels = new ArrayList<>();
+        if (wheels != null) {
+            for (Wheel w : wheels) {
+                this.wheels.add(new Wheel(w));
+            }
+        }
+
+        // deep copy of engine
+        this.engine = engine == null ? null : new Engine(engine);
+    }
+
+    public int getYear() {
+        return year;
+    }
+
+    public String getColor() {
+        return color;
+    }
+
+    // return deep copy
+    public List<Wheel> getWheels() {
+        List<Wheel> copy = new ArrayList<>();
+        for (Wheel w : wheels) {
+            copy.add(new Wheel(w));
+        }
+        return copy;
+    }
+
+    public Engine getEngine() {
+        return engine == null ? null : new Engine(engine);
+    }
+
+    // "change engine" = new Car
+    public Car changeEngine(Engine newEngine) {
+        return new Car(this.year, this.color, this.wheels, newEngine);
+    }
+
+    // "change color" = new Car
+    public Car changeColor(String newColor) {
+        return new Car(this.year, newColor, this.wheels, this.engine);
+    }
+
+    // "add wheel" = new Car
+    public Car addWheel(Wheel newWheel) {
+        List<Wheel> newWheels = new ArrayList<>(this.wheels);
+        newWheels.add(new Wheel(newWheel));
+        return new Car(this.year, this.color, newWheels, this.engine);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        Car car = (Car) o;
+        return year == car.year &&
+                Objects.equals(color, car.color) &&
+                Objects.equals(wheels, car.wheels) &&
+                Objects.equals(engine, car.engine);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(year, color, wheels, engine);
+    }
 
     @Override
     public String toString() {
-        return "Car{"
-            + "year=" + year
-            + ", color='" + color + '\''
-            + ", wheels=" + wheels
-            + ", engine=" + engine
-            + '}';
+        return "Car{" +
+                "year=" + year +
+                ", color='" + color + '\'' +
+                ", wheels=" + wheels +
+                ", engine=" + engine +
+                '}';
     }
 }

src/main/java/core/basesyntax/Engine.java

@@ -1,16 +1,51 @@
 package core.basesyntax;
 
-public class Engine {
-    private int horsePower;
-    private String manufacturer;
+public final class Engine {
+    private final int horsePower;
+    private final String manufacturer;
 
-    //implement this class
+    public Engine(int horsePower, String manufacturer) {
+        this.horsePower = horsePower;
+        this.manufacturer = manufacturer;
+    }
+
+    public Engine(Engine other) {
+        this.horsePower = other.horsePower;
+        this.manufacturer = other.manufacturer;
+    }
+
+    public int getHorsePower() {
+        return horsePower;
+    }
+
+    public String getManufacturer() {
+        return manufacturer;
+    }
+
+    // "upgrade engine" = create new instance
+    public Engine changeEngine(Engine engine) {
+        return new Engine(engine);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Engine engine = (Engine) o;
+        return horsePower == engine.horsePower &&
+                java.util.Objects.equals(manufacturer, engine.manufacturer);
+    }
+
+    @Override
+    public int hashCode() {
+        return java.util.Objects.hash(horsePower, manufacturer);
+    }
 
     @Override
     public String toString() {
-        return "Engine{"
-            + "horsePower=" + horsePower
-            + ", manufacturer='" + manufacturer + '\''
-            + '}';
+        return "Engine{" +
+                "horsePower=" + horsePower +
+                ", manufacturer='" + manufacturer + '\'' +
+                '}';
     }
 }

src/main/java/core/basesyntax/Wheel.java

@@ -1,14 +1,35 @@
 package core.basesyntax;
 
-public class Wheel {
-    private int radius;
+public final class Wheel {
+    private final int radius;
 
-    //implement this class
+    public Wheel(int radius) {
+        this.radius = radius;
+    }
+
+    public int getRadius() {
+        return radius;
+    }
+
+    public Wheel(Wheel other) {
+        this.radius = other.radius;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Wheel wheel = (Wheel) o;
+        return radius == wheel.radius;
+    }
+
+    @Override
+    public int hashCode() {
+        return Integer.hashCode(radius);
+    }
 
     @Override
     public String toString() {
-        return "Wheel{"
-            + "radius=" + radius
-            + '}';
+        return "Wheel{" + "radius=" + radius + '}';
     }
 }