Some fields and methods where non-static and I changed them to static.

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

@@ -25,13 +25,12 @@ public class NTtBProtocolParser implements ProtocolParser {
       throws NoLegalProtocolCommandStringFoundException, EmptyClientInputException {
     Scanner sc = new Scanner(msg);
     ArrayList<String> input = new ArrayList<>();
-    String parsedMsg = buildProtocolMsg(input);
+    String parsedMsg;
 
     while (sc.hasNext()) {
       input.add(sc.next());
     }
-
-    return parsedMsg;
+    return buildProtocolMsg(input);
   }
 
 
@@ -42,7 +41,7 @@ public class NTtBProtocolParser implements ProtocolParser {
       throw new EmptyClientInputException(caller);
     }
     StringBuilder s = new StringBuilder(); //friendly little helper
-    s.append(legalCommands.encode(input.get(0)));
+    s.append(InputToProtocolMap.encode(input.get(0)));
     if (containsParameters(input)) {
       int size = input.size();
       for (int i = 1; i < size; i++) {

src/main/java/ch/unibas/dmi/dbis/cs108/multiplayer/protocol/NightTrainProtocol.java

@@ -49,11 +49,11 @@ public class NightTrainProtocol {
      * @param cmd, the string command to be validated
      * @return true if <code>cmd</code> is a valid command
      */
-    public boolean isLegalCmdString(String cmd) {
+    public static boolean isLegalCmdString(String cmd) {
         return legalStrings.contains(cmd);
     }
 
-    public NTtBCommands getCmdEnumObject(String cmd) throws NoLegalProtocolCommandStringFoundException {
+    public static NTtBCommands getCmdEnumObject(String cmd) throws NoLegalProtocolCommandStringFoundException {
         if(isLegalCmdString(cmd)){
             return stringNTtBCommandsHashMap.get(cmd);
         } else {

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

@@ -18,9 +18,9 @@ public class ClientHandler implements Runnable  {
     private ClientMsgDecoder clientMsgDecoder = new ClientMsgDecoder();
 
     /**
-     * Implements the connecting logik in client-server
+     * Implements the login logik in client-server
      * architecture.
-     * @param socket
+     * @param socket the socket on which to make the connection.
      */
     public ClientHandler(Socket socket) {
         try {
@@ -66,7 +66,9 @@ public class ClientHandler implements Runnable  {
 
     @Override
     /**
-     * point of contact for client and server.
+     * The main logik of the client handler.
+     * Since every client is put on a string this is where
+     * most interactions between client and server are held..
      */
     public void run() {
         String msg;

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

@@ -17,8 +17,6 @@ import ch.unibas.dmi.dbis.cs108.multiplayer.protocol.ProtocolDecoder;
 
 public class ClientMsgDecoder implements ProtocolDecoder {
 
-  private NightTrainProtocol protocol;
-
   /**
    * The point of contact for the ClientHandler who calls this method to convert a String in to
    * usable, tokanized format defined by {@link NTtBFormatMsg}.
@@ -78,7 +76,7 @@ public class ClientMsgDecoder implements ProtocolDecoder {
    */
   private NightTrainProtocol.NTtBCommands getCommandConstant(String stringToken) {
     try {
-      return protocol.getCmdEnumObject(stringToken);
+      return NightTrainProtocol.getCmdEnumObject(stringToken);
     } catch (NoLegalProtocolCommandStringFoundException e) {
       return NightTrainProtocol.NTtBCommands.SEROR;
     }