diff --git a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Car.java b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Car.java
index 11923be671..d9d2fbd192 100644
--- a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Car.java
+++ b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Car.java
@@ -2,41 +2,41 @@ package com.baeldung.interface_vs_abstract_class;
 
 public class Car extends Vehicle {
 
-	public Car(String vechicleName) {
-		super(vechicleName);
-	}
+    public Car(String vechicleName) {
+        super(vechicleName);
+    }
 
-	public Car(String vechicleName, String vehicleModel) {
-		super(vechicleName, vehicleModel);
-	}
+    public Car(String vechicleName, String vehicleModel) {
+        super(vechicleName, vehicleModel);
+    }
 
-	public Car(String vechicleName, String vehicleModel, Long makeYear) {
-		super(vechicleName, vehicleModel, makeYear);
-	}
+    public Car(String vechicleName, String vehicleModel, Long makeYear) {
+        super(vechicleName, vehicleModel, makeYear);
+    }
 
-	@Override
-	protected void start() {
-		// code implementation details on starting a car.
-	}
+    @Override
+    protected void start() {
+        // code implementation details on starting a car.
+    }
 
-	@Override
-	protected void stop() {
-		// code implementation details on stopping a car.
-	}
+    @Override
+    protected void stop() {
+        // code implementation details on stopping a car.
+    }
 
-	@Override
-	protected void drive() {
-		// code implementation details on start driving a car.
-	}
+    @Override
+    protected void drive() {
+        // code implementation details on start driving a car.
+    }
 
-	@Override
-	protected void changeGear() {
-		// code implementation details on changing the car gear.
-	}
+    @Override
+    protected void changeGear() {
+        // code implementation details on changing the car gear.
+    }
 
-	@Override
-	protected void reverse() {
-		// code implementation details on reverse driving a car.
-	}
+    @Override
+    protected void reverse() {
+        // code implementation details on reverse driving a car.
+    }
 
 }
diff --git a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/ImageSender.java b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/ImageSender.java
index ccaee8157d..664a7bc951 100644
--- a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/ImageSender.java
+++ b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/ImageSender.java
@@ -4,9 +4,9 @@ import java.io.File;
 
 public class ImageSender implements Sender {
 
-	@Override
-	public void send(File fileToBeSent) {
-		// image sending implementation code.
-	}
+    @Override
+    public void send(File fileToBeSent) {
+        // image sending implementation code.
+    }
 
 }
\ No newline at end of file
diff --git a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Sender.java b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Sender.java
index 72aa4a7681..88e65fabf2 100644
--- a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Sender.java
+++ b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Sender.java
@@ -4,5 +4,5 @@ import java.io.File;
 
 public interface Sender {
 
-	void send(File fileToBeSent);
+    void send(File fileToBeSent);
 }
diff --git a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Vehicle.java b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Vehicle.java
index 0661ddbdf4..4d9a5c2ae6 100644
--- a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Vehicle.java
+++ b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/Vehicle.java
@@ -2,56 +2,56 @@ package com.baeldung.interface_vs_abstract_class;
 
 public abstract class Vehicle {
 
-	private String vehicleName;
-	private String vehicleModel;
-	private Long makeYear;
+    private String vehicleName;
+    private String vehicleModel;
+    private Long makeYear;
 
-	public Vehicle(String vehicleName) {
-		this.vehicleName = vehicleName;
-	}
+    public Vehicle(String vehicleName) {
+        this.vehicleName = vehicleName;
+    }
 
-	public Vehicle(String vehicleName, String vehicleModel) {
-		this(vehicleName);
-		this.vehicleModel = vehicleModel;
-	}
+    public Vehicle(String vehicleName, String vehicleModel) {
+        this(vehicleName);
+        this.vehicleModel = vehicleModel;
+    }
 
-	public Vehicle(String vechicleName, String vehicleModel, Long makeYear) {
-		this(vechicleName, vehicleModel);
-		this.makeYear = makeYear;
-	}
+    public Vehicle(String vechicleName, String vehicleModel, Long makeYear) {
+        this(vechicleName, vehicleModel);
+        this.makeYear = makeYear;
+    }
 
-	public String getVehicleName() {
-		return vehicleName;
-	}
+    public String getVehicleName() {
+        return vehicleName;
+    }
 
-	public void setVehicleName(String vehicleName) {
-		this.vehicleName = vehicleName;
-	}
+    public void setVehicleName(String vehicleName) {
+        this.vehicleName = vehicleName;
+    }
 
-	public String getVehicleModel() {
-		return vehicleModel;
-	}
+    public String getVehicleModel() {
+        return vehicleModel;
+    }
 
-	public void setVehicleModel(String vehicleModel) {
-		this.vehicleModel = vehicleModel;
-	}
+    public void setVehicleModel(String vehicleModel) {
+        this.vehicleModel = vehicleModel;
+    }
 
-	public Long getMakeYear() {
-		return makeYear;
-	}
+    public Long getMakeYear() {
+        return makeYear;
+    }
 
-	public void setMakeYear(Long makeYear) {
-		this.makeYear = makeYear;
-	}
+    public void setMakeYear(Long makeYear) {
+        this.makeYear = makeYear;
+    }
 
-	protected abstract void start();
+    protected abstract void start();
 
-	protected abstract void stop();
+    protected abstract void stop();
 
-	protected abstract void drive();
+    protected abstract void drive();
 
-	protected abstract void changeGear();
+    protected abstract void changeGear();
 
-	protected abstract void reverse();
+    protected abstract void reverse();
 
 }
diff --git a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/VideoSender.java b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/VideoSender.java
index 08be38fe98..61a89615c9 100644
--- a/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/VideoSender.java
+++ b/core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interface_vs_abstract_class/VideoSender.java
@@ -4,9 +4,9 @@ import java.io.File;
 
 public class VideoSender implements Sender {
 
-	@Override
-	public void send(File fileToBeSent) {
-		// video sending implementation code
-	}
+    @Override
+    public void send(File fileToBeSent) {
+        // video sending implementation code
+    }
 
 }
\ No newline at end of file
diff --git a/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/SenderUnitTest.java b/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/SenderUnitTest.java
index 154eb2876e..76712ab868 100644
--- a/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/SenderUnitTest.java
+++ b/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/SenderUnitTest.java
@@ -7,14 +7,14 @@ import java.io.File;
 
 class SenderUnitTest {
 
-	public final static String IMAGE_FILE_PATH = "/sample_image_file_path/photo.jpg";
+    public final static String IMAGE_FILE_PATH = "/sample_image_file_path/photo.jpg";
 
-	@Test
-	void givenImageUploaded_whenButtonClicked_thenSendImage() {
-		File imageFile = new File(IMAGE_FILE_PATH);
+    @Test
+    void givenImageUploaded_whenButtonClicked_thenSendImage() {
+        File imageFile = new File(IMAGE_FILE_PATH);
 
-		Sender sender = new ImageSender();
-		sender.send(imageFile);
-	}
+        Sender sender = new ImageSender();
+        sender.send(imageFile);
+    }
 
 }
diff --git a/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/VehicleUnitTest.java b/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/VehicleUnitTest.java
index 23a18d922a..baf4a5d648 100644
--- a/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/VehicleUnitTest.java
+++ b/core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interface_vs_abstract_class/VehicleUnitTest.java
@@ -6,14 +6,14 @@ import org.junit.jupiter.api.Test;
 
 class VehicleUnitTest {
 
-	@Test
-	void givenVehicle_whenNeedToDrive_thenStart() {
-		Vehicle car = new Car("BMW");
+    @Test
+    void givenVehicle_whenNeedToDrive_thenStart() {
+        Vehicle car = new Car("BMW");
 
-		car.start();
-		car.drive();
-		car.changeGear();
-		car.stop();
-	}
+        car.start();
+        car.drive();
+        car.changeGear();
+        car.stop();
+    }
 
 }