Added name duplicate handler by modifying the ClientHandler class as well as adding a class where all Client names are stored

src/main/java/ch/unibas/dmi/dbis/cs108/multiplayer/client/Client.java

@@ -1,6 +1,7 @@
 package ch.unibas.dmi.dbis.cs108.multiplayer.client;
 
 import ch.unibas.dmi.dbis.cs108.multiplayer.protocol.NoLegalProtocolCommandStringFoundException;
+import ch.unibas.dmi.dbis.cs108.multiplayer.server.NameGenerator;
 
 import java.net.Socket;
 import java.io.*;
@@ -20,7 +21,6 @@ public class Client {
       this.out = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
       this.in = new BufferedReader((new InputStreamReader((socket.getInputStream()))));
 
-      String randomUserName = NameGenerator.randomName();
       //TODO hide connecting logik(next 4 lines)
       this.userName = userName;
       this.out.write(getUsername());
@@ -147,4 +147,6 @@ public class Client {
   public String getUsername() {
     return userName;
   }
+
 }
+

src/main/java/ch/unibas/dmi/dbis/cs108/multiplayer/server/AllClientNames.java

@@ -0,0 +1,14 @@
+package ch.unibas.dmi.dbis.cs108.multiplayer.server;
+
+/* This class is built to contain the usernames of all players in a single string.
+* This allows a duplicate check (--> ClientHandler) when a new player chooses
+* a name: does the string with all the previous names contain the new player's
+* desired username? If yes, he is being assigned a random name. If no, he can keep
+* his desired name. */
+
+public class AllClientNames {
+    static StringBuilder names = new StringBuilder();
+    public static String allNames(String currentName) {
+        return names.append(currentName).toString();
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/multiplayer/server/ClientHandler.java

@@ -28,6 +28,14 @@ public class ClientHandler implements Runnable  {
             this.out = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
             this.in = new BufferedReader((new InputStreamReader((socket.getInputStream()))));
             this.clientUserName = in.readLine();
+
+            // duplicate handling: if username already taken, assign random name to client
+            if (AllClientNames.allNames("").contains(clientUserName)) {
+                clientUserName = NameGenerator.randomName();
+            }
+            // add username to list of all client names for future duplicate checking
+            AllClientNames.allNames(clientUserName);
+
             connectedClients.add(this);
             broadcastMessage("SERVER: " + clientUserName + " has joined the Server");
         } catch (IOException e) {

src/main/java/ch/unibas/dmi/dbis/cs108/multiplayer/server/NameGenerator.java

@@ -1,4 +1,4 @@
-package ch.unibas.dmi.dbis.cs108.multiplayer.client;
+package ch.unibas.dmi.dbis.cs108.multiplayer.server;
 
 import java.util.Random;