added logger to project

.gitignore

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

log/app.log

@@ -0,0 +1,7 @@
+2026-07-07 19:10:23 [main] INFO  mate.academy.service.AuthenticationServiceImpl - Method login was called for user: bob
+2026-07-07 19:10:23 [main] INFO  mate.academy.service.AuthenticationServiceImpl - User bob successfully logged in.
+2026-07-07 19:10:23 [main] INFO  mate.academy.service.OrderServiceImpl - Method completeOrder was called for user Id: 2
+2026-07-07 19:12:49 [main] INFO  mate.academy.service.AuthenticationServiceImpl - Method login was called for user: bob
+2026-07-07 19:12:49 [main] INFO  mate.academy.service.AuthenticationServiceImpl - User bob successfully logged in.
+2026-07-07 19:12:49 [main] INFO  mate.academy.service.OrderServiceImpl - Method completeOrder was called for user Id: 2
+2026-07-07 19:12:49 [main] INFO  mate.academy.service.OrderServiceImpl - Successfully fetched data from DB for user Id: 2. Retracted 3 products.

pom.xml

@@ -24,7 +24,29 @@
             <version>4.12</version>
             <scope>test</scope>
         </dependency>
+
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>2.0.12</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-core</artifactId>
+            <version>2.23.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-slf4j2-impl</artifactId>
+            <version>2.23.1</version>
+        </dependency>
+
     </dependencies>
+
+
     <build>
         <plugins>
             <plugin>

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

@@ -6,16 +6,23 @@
 import mate.academy.service.AuthenticationServiceImpl;
 import mate.academy.service.OrderService;
 import mate.academy.service.OrderServiceImpl;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class Main {
+
+    private static final Logger logger = LoggerFactory.getLogger(Main.class);
+
     public static void main(String[] args) {
+
         AuthenticationService authenticationService = new AuthenticationServiceImpl();
         User user;
         try {
             user = authenticationService.login("bob", "1234");
+            logger.info("User bob tries to login");
         } catch (AuthenticationException e) {
-            e.printStackTrace();
-            return;
+            logger.error("Authentification failed for user bob");
+            throw new RuntimeException("Authentification failed for user bob");
         }
         OrderService orderService = new OrderServiceImpl();
         orderService.completeOrder(user.getUserId());

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

@@ -1,23 +1,38 @@
 package mate.academy.service;
 
+import java.util.Objects;
 import mate.academy.exception.AuthenticationException;
 import mate.academy.model.User;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class AuthenticationServiceImpl implements AuthenticationService {
+
+    private static final Logger logger = LoggerFactory.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 for user:{}", login);
         User user = findByLogin(login);
-        if (!user.getPassword().equals(password)) {
-            throw new AuthenticationException("Username or password are incorrect");
+
+        if (user == null || !Objects.equals(user.getPassword(), password)) {
+            logger.error("Failed login attempt for user: {}", login);
+            throw new AuthenticationException("Failed login attempt for user");
         }
+
+        logger.info("User {} successfully logged in.", login);
         return user;
     }
 
     private User findByLogin(String login) {
-        User user = new User(login, "1234");
-        // this user identifier should be set by DB. We will use dummy data for this example
-        user.setUserId(2L);
-        return user;
+        if ("bob".equals(login)) {
+            User user = new User(login, "1234");
+            user.setUserId(2L);
+            return user;
+        }
+        return null;
     }
 }
+
+
+

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

@@ -4,27 +4,30 @@
 import java.util.List;
 import mate.academy.model.Order;
 import mate.academy.model.Product;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class OrderServiceImpl implements OrderService {
+
+    private static final Logger logger = LoggerFactory.getLogger(OrderServiceImpl.class);
+
     @Override
     public Order completeOrder(Long userId) {
-        // TODO: add log message about method completeOrder was called
+        logger.info("Method completeOrder was called for user Id: {}",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("Successfully fetched data from DB for user with Id: {}. ", userId);
         return products;
     }
 }

src/main/resources/log4j2.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="WARN">
+    <Properties>
+        <Property name="basePath">logs</Property>
+    </Properties>
+
+    <Appenders>
+        <Console name="ConsoleAppender" target="SYSTEM_OUT">
+            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} [%t] %-5level %logger{36} - %msg%n"/>
+        </Console>
+
+        <File name="FileAppender" fileName="log/app.log" append="true">
+            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} [%t] %-5level %logger{36} - %msg%n"/>
+        </File>
+    </Appenders>
+
+    <Loggers>
+        <Root level="info">
+            <AppenderRef ref="ConsoleAppender"/>
+            <AppenderRef ref="FileAppender"/>
+        </Root>
+    </Loggers>
+</Configuration>