for check

.gitignore

@@ -1,3 +1,4 @@
 .idea/*
 *.iml
 target/*
+/logs

pom.xml

@@ -18,6 +18,12 @@
     </properties>
 
     <dependencies>
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-core</artifactId>
+            <version>2.26.0</version>
+            <scope>compile</scope>
+        </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>

src/main/java/mate/academy/Main.java

@@ -6,18 +6,22 @@
 import mate.academy.service.AuthenticationServiceImpl;
 import mate.academy.service.OrderService;
 import mate.academy.service.OrderServiceImpl;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 public class Main {
+    private static final Logger logger = LogManager.getLogger(Main.class);
+
     public static void main(String[] args) {
         AuthenticationService authenticationService = new AuthenticationServiceImpl();
         User user;
         try {
             user = authenticationService.login("bob", "1234");
+            OrderService orderService = new OrderServiceImpl();
+            orderService.completeOrder(user.getUserId());
         } catch (AuthenticationException e) {
-            e.printStackTrace();
-            return;
+            logger.error("User can`t login", e);
         }
-        OrderService orderService = new OrderServiceImpl();
-        orderService.completeOrder(user.getUserId());
+
     }
 }

src/main/java/mate/academy/service/AuthenticationServiceImpl.java

@@ -2,11 +2,15 @@
 
 import mate.academy.exception.AuthenticationException;
 import mate.academy.model.User;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 public class AuthenticationServiceImpl implements AuthenticationService {
+    private static final Logger logger = LogManager.getLogger(AuthenticationServiceImpl.class);
+
     @Override
     public User login(String login, String password) throws AuthenticationException {
-        //TODO: add corresponding log message about method login was called
+        logger.info("Method login was called. Params: login {}", login);
         User user = findByLogin(login);
         if (!user.getPassword().equals(password)) {
             throw new AuthenticationException("Username or password are incorrect");

src/main/java/mate/academy/service/OrderServiceImpl.java

@@ -4,27 +4,27 @@
 import java.util.List;
 import mate.academy.model.Order;
 import mate.academy.model.Product;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 public class OrderServiceImpl implements OrderService {
+    private static final Logger logger = LogManager.getLogger(OrderServiceImpl.class);
+
     @Override
     public Order completeOrder(Long userId) {
-        // TODO: add log message about method completeOrder was called
+        logger.info("Method completeOrder was called. Params: userId {}", userId);
         List<Product> products = getAllProductsFromShoppingCart(userId);
         Order order = new Order(products, userId);
-        // NOTE: In production ready code this order identifier should be generated by DB
-        // For test purpose we simplify this and return dummy data
         order.setOrderId(1L);
         return order;
     }
 
     private List<Product> getAllProductsFromShoppingCart(Long userId) {
-        // NOTE: In production ready code this method should fetch data from DB
-        // For test purpose we simplify this method and return dummy data
         Product iphone = new Product("iPhone X", BigDecimal.valueOf(1199));
         Product macBook = new Product("MacBook Air 2020", BigDecimal.valueOf(1399));
         Product xiaomi = new Product("Xiaomi 12", BigDecimal.valueOf(499));
         List<Product> products = List.of(iphone, macBook, xiaomi);
-        // TODO: add log message about successful fetched data from DB
+        logger.info("Data from DB was successfully fetched");
         return products;
     }
 }

src/main/resources/log4j2.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="info">
+    <Appenders>
+        <Console name="LogToConsole" target="SYSTEM_OUT">
+            <PatternLayout pattern="%d{HH:mm:ss.SSS} %-5level %logger{36} - %msg%n"/>
+        </Console>
+        <File name="LogToFile" fileName="logs/app.log">
+            <PatternLayout>
+                <Pattern>%d %p %c:%L %msg%n</Pattern>
+            </PatternLayout>
+        </File>
+    </Appenders>
+    <Loggers>
+        <Logger name="mate.academy" level="info" additivity="false">
+            <AppenderRef ref="LogToFile"/>
+            <AppenderRef ref="LogToConsole"/>
+        </Logger>
+        <Root level="error">
+            <AppenderRef ref="LogToFile"/>
+            <AppenderRef ref="LogToConsole"/>
+        </Root>
+    </Loggers>
+</Configuration>