diff --git a/Hometask_6/pom.xml b/Hometask_6/pom.xml
new file mode 100644
index 0000000..fad4e10
--- /dev/null
+++ b/Hometask_6/pom.xml
@@ -0,0 +1,57 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>ru.geekbrains</groupId>
+    <artifactId>gb-unittest</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.0</version>
+                <configuration>
+                    <release>11</release>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.7.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/org.apache.maven.plugins/maven-compiler-plugin -->
+        <dependency>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <version>3.8.0</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.7.0</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <version>5.7.0</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>1.2.17</version>
+        </dependency>
+    </dependencies>
+</project>
\ No newline at end of file
diff --git a/Hometask_6/src/main/java/homework_6/Task2.java b/Hometask_6/src/main/java/homework_6/Task2.java
new file mode 100644
index 0000000..1838504
--- /dev/null
+++ b/Hometask_6/src/main/java/homework_6/Task2.java
@@ -0,0 +1,38 @@
+package homework_6;
+
+import java.util.Arrays;
+
+public class Task2 {
+
+    public int[] getNumbersAfterLast4(int[] array){
+
+        int[] result;
+        if (array == null){
+            throw new NullPointerException();
+        }
+        if (array.length == 0){
+            throw new IllegalArgumentException("The length of array could not be 0 ");
+        }
+
+        int count=-1;
+        for (int i = 0; i < array.length; i++) {
+            if (array[i]==4){
+                count=i;
+            }
+        }
+        if (count==-1){
+            throw new RuntimeException();
+        }
+        if (count==array.length-1){
+            return null;
+        } else {
+                result = new int[array.length-1 - count];
+            for (int i = count+1; i < array.length; i++) {
+                result[i-count-1] = array[i];
+            }
+        }
+        System.out.println(Arrays.toString(result));
+        return result;
+    }
+
+}
diff --git a/Hometask_6/src/main/java/homework_6/Task_3.java b/Hometask_6/src/main/java/homework_6/Task_3.java
new file mode 100644
index 0000000..a976bbc
--- /dev/null
+++ b/Hometask_6/src/main/java/homework_6/Task_3.java
@@ -0,0 +1,25 @@
+package homework_6;
+
+import java.util.Arrays;
+
+public class Task_3 {
+    public boolean chekElementsOfArray( int[] array){
+        if (array == null){
+            throw new NullPointerException();
+        }
+        if (array.length == 0){
+            throw new IllegalArgumentException("The length of array could not be 0 ");
+        }
+         long countOfOne = Arrays.stream(array)
+                            .filter(x->x==1)
+                            .count();
+        long countOfFour = Arrays.stream(array)
+                            .filter(x->x==4)
+                             .count();
+        if (countOfFour==0 || countOfOne==0){
+            return false;
+        }
+        return countOfFour+countOfOne == array.length;
+
+    }
+}
diff --git a/Hometask_6/src/main/java/homework_6/test.java b/Hometask_6/src/main/java/homework_6/test.java
new file mode 100644
index 0000000..13662cb
--- /dev/null
+++ b/Hometask_6/src/main/java/homework_6/test.java
@@ -0,0 +1,10 @@
+package homework_6;
+
+public class test {
+    public static void main(String[] args) {
+        int [] a  = new int[0];
+        for (int i : a) {
+            System.out.println(i);
+        }
+    }
+}
diff --git a/Hometask_6/src/main/java/server/ServerChat.java b/Hometask_6/src/main/java/server/ServerChat.java
new file mode 100644
index 0000000..b702f02
--- /dev/null
+++ b/Hometask_6/src/main/java/server/ServerChat.java
@@ -0,0 +1,97 @@
+package server;
+
+import org.apache.log4j.Logger;
+
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.Date;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+
+public class ServerChat implements Chat {
+    private static final Logger logger = Logger.getLogger(ServerChat.class);
+    private ServerSocket serverSocket;
+    private Set<ClientHandler> clients;
+    private AuthenticationService authenticationService;
+
+    public ServerChat() {
+        start();
+    }
+
+
+    @Override
+    public AuthenticationService getAuthenticationService() {
+        return authenticationService;
+    }
+
+    private void start() {
+        try {
+            serverSocket = new ServerSocket(9998);
+            String startMessage = "Server started";
+            logger.info(startMessage);
+            clients = new HashSet<>();
+            authenticationService = new AuthenticationService();
+
+            while (true) {
+
+                System.out.println("Server is waiting for a connection ...");
+                Socket socket = serverSocket.accept();
+                ClientHandler clientHandler = new ClientHandler(socket, this);
+                System.out.println(String.format("[%s] Client[%s] is successfully logged in", new Date(), clientHandler.getName()));
+            }
+        } catch (Exception e) {
+            logger.error("An error :" +e.getMessage());
+            e.printStackTrace();
+        }
+    }
+
+
+    @Override
+    public synchronized void broadcastMessage(String message) {
+        for (ClientHandler client : clients) {
+            client.sendMessage(message);
+        }
+        logger.info(message);
+    }
+
+    @Override
+    public synchronized boolean isNicknameOccupied(String nickname) {
+        for (ClientHandler client : clients) {
+            if (client.getName().equals(nickname)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public synchronized void subscribe(ClientHandler client) {
+        clients.add(client);
+        logger.info(client.getName()+ "connected to server");
+
+    }
+
+    @Override
+    public synchronized void unsubscribe(ClientHandler client) {
+        clients.remove(client);
+        logger.info(client.getName() + "disconnected from server");
+    }
+    @Override
+    public void sendPrivateMessage(String privateMessage, ClientHandler clientHandler, String destName) {
+            ClientHandler dest = getClientByNickname(destName);
+        if (Objects.nonNull(dest)){
+
+            dest.sendMessage(String.format("[%s private 4u] : %s", clientHandler.getName(), privateMessage));
+        } else {
+            clientHandler.sendMessage(String.format("[%s] is offline. Cannot send message",  destName));
+        }
+    }
+    private ClientHandler getClientByNickname( String name){
+        for (ClientHandler s : clients) {
+            if (s.getName().equals(name)) return s;
+        }
+        return null;
+    }
+}
diff --git a/Hometask_6/src/main/resources/log4j.properties b/Hometask_6/src/main/resources/log4j.properties
new file mode 100644
index 0000000..3c3c96f
--- /dev/null
+++ b/Hometask_6/src/main/resources/log4j.properties
@@ -0,0 +1,16 @@
+# Root logger option
+log4j.rootLogger=DEBUG, stdout, file
+
+# Redirect log messages to console
+log4j.appender.stdout=org.apache.log4j.ConsoleAppender
+log4j.appender.stdout.Target=System.out
+log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
+log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
+
+# Redirect log messages to a log file, support file rolling.
+log4j.appender.file=org.apache.log4j.RollingFileAppender
+log4j.appender.file.File=logs.log
+log4j.appender.file.MaxFileSize=5MB
+log4j.appender.file.MaxBackupIndex=10
+log4j.appender.file.layout=org.apache.log4j.PatternLayout
+log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
\ No newline at end of file
diff --git a/Hometask_6/src/test/java/homework_6_test/Task_2_Test.java b/Hometask_6/src/test/java/homework_6_test/Task_2_Test.java
new file mode 100644
index 0000000..711a564
--- /dev/null
+++ b/Hometask_6/src/test/java/homework_6_test/Task_2_Test.java
@@ -0,0 +1,57 @@
+package homework_6_test;
+
+import homework_6.Task2;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import java.util.stream.Stream;
+
+
+public class Task_2_Test {
+    private Task2 t2 = new Task2();
+
+    @ParameterizedTest
+    @MethodSource("arraysProvider1")
+    void shouldReturnAnArrayOfIntNumbersFollowingTheLastFour(int[] expected, int[] source) {
+        Assertions.assertArrayEquals(expected, t2.getNumbersAfterLast4(source));
+    }
+    @ParameterizedTest
+    @MethodSource("arraysProvider2")
+    void shouldReturnNullIfDigit4IsTheLastElementOfSourceArray(int[] expected, int[] source) {
+        Assertions.assertArrayEquals(expected, t2.getNumbersAfterLast4(source));
+    }
+
+    @Test
+    void shouldThrowNullPointerExceptionWhenInputIsNull(){
+        Assertions.assertThrows(NullPointerException.class,()-> t2.getNumbersAfterLast4(null));
+    }
+    @Test
+    void shouldIllegalArgumentExceptionWhenInputArrayContainsNoElements(){
+        Assertions.assertThrows(IllegalArgumentException.class,()-> t2.getNumbersAfterLast4(new int[0]));
+    }
+    @Test
+    void shouldThrowRuntimeExceptionWhenInputArrayDoesNotContainDigit4(){
+        Assertions.assertThrows(RuntimeException.class,()-> t2.getNumbersAfterLast4(new int[]{1,2,3,5,6}));
+    }
+
+    private static Stream<Arguments> arraysProvider1() {
+        return Stream.of(
+                Arguments.arguments(new int[]{1, 7},new int[]{1,2,4,4,2,3,4,1,7}),
+                Arguments.arguments(null, new int[]{1,4}),
+                Arguments.arguments(null, new int[]{4}),
+                Arguments.arguments(new int[]{1}, new int[]{4,1}),
+                Arguments.arguments(new int[]{3,3,3,3,3,3,5}, new int[]{4,1,4,3,3,3,3,3,3,5})
+
+        );
+    }
+    private static Stream<Arguments> arraysProvider2() {
+        return Stream.of(
+                Arguments.arguments(null, new int[]{1,4}),
+                Arguments.arguments(null, new int[]{4}),
+                Arguments.arguments(null, new int[]{1,2,3,3,3,3,3,3,4})
+
+        );
+    }
+}
diff --git a/Hometask_6/src/test/java/homework_6_test/Task_3_Test.java b/Hometask_6/src/test/java/homework_6_test/Task_3_Test.java
new file mode 100644
index 0000000..ab82757
--- /dev/null
+++ b/Hometask_6/src/test/java/homework_6_test/Task_3_Test.java
@@ -0,0 +1,39 @@
+package homework_6_test;
+
+import homework_6.Task_3;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.stream.Stream;
+
+public class Task_3_Test {
+    Task_3 t3 = new Task_3();
+
+    @ParameterizedTest
+    @MethodSource("resultProvider")
+    void shouldCheckIfArrayContainsOnlyNumbers1and4(boolean expected, int[] source) {
+        Assertions.assertEquals(expected, t3.chekElementsOfArray(source));
+    }
+
+    @Test
+    void shouldThrowNullPointerExceptionWhenInputIsNull() {
+        Assertions.assertThrows(NullPointerException.class, () -> t3.chekElementsOfArray(null));
+    }
+    @Test
+    void shouldIllegalArgumentExceptionWhenInputArrayContainsNoElements(){
+        Assertions.assertThrows(IllegalArgumentException.class,()-> t3.chekElementsOfArray(new int[0]));
+    }
+
+    private static Stream<Arguments> resultProvider() {
+        return Stream.of(
+                Arguments.arguments(true, new int[]{1, 1, 1, 4, 4, 1, 4, 4}),
+                Arguments.arguments(false, new int[]{1, 1, 1, 1, 1, 1}),
+                Arguments.arguments(false, new int[]{4, 4, 4, 4}),
+                Arguments.arguments(false, new int[]{1, 4, 4, 1, 1, 4, 3})
+
+        );
+    }
+}
diff --git a/Hometask_6/target/classes/log4j.properties b/Hometask_6/target/classes/log4j.properties
new file mode 100644
index 0000000..3c3c96f
--- /dev/null
+++ b/Hometask_6/target/classes/log4j.properties
@@ -0,0 +1,16 @@
+# Root logger option
+log4j.rootLogger=DEBUG, stdout, file
+
+# Redirect log messages to console
+log4j.appender.stdout=org.apache.log4j.ConsoleAppender
+log4j.appender.stdout.Target=System.out
+log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
+log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
+
+# Redirect log messages to a log file, support file rolling.
+log4j.appender.file=org.apache.log4j.RollingFileAppender
+log4j.appender.file.File=logs.log
+log4j.appender.file.MaxFileSize=5MB
+log4j.appender.file.MaxBackupIndex=10
+log4j.appender.file.layout=org.apache.log4j.PatternLayout
+log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
\ No newline at end of file
diff --git a/Hometask_6/target/maven-status/maven-compiler-plugin/compile/default-cli/inputFiles.lst b/Hometask_6/target/maven-status/maven-compiler-plugin/compile/default-cli/inputFiles.lst
new file mode 100644
index 0000000..e69de29