Finally box, connectionToServer

src/main/java/ChatClient.java

@@ -61,6 +61,15 @@ public class ChatClient extends JFrame implements KeyListener {
         catch (Exception e) {
             JOptionPane.showMessageDialog(null, "Verbindung zum Server \"" + address + "\" fehlgeschlagen.");
         }
+        finally {
+        	try {
+				connectionToServer.close();
+			} catch (IOException e) {
+				// TODO Auto-generated catch block
+				e.printStackTrace();
+			}
+        	
+        }
     }
 
     @Override