Python Server / Android Client-Socket-Error

    con = sqlite3.connect(SQL_Adressdateien)
    cursor = con.cursor()
    cursor.execute('''CREATE TABLE IF NOT EXISTS Adressenliste(id INTEGER PRIMARY KEY, ktoNum INT UNIQUE, vorName TEXT, nachName TEXT , gebDat TEXT, pLz INT, wohnOrt TEXT)''')
    cursor = con.cursor()
    cursor.execute('''SELECT ktoNum,vorName,nachName,gebDat,pLz FROM Adressenliste WHERE ktoNum=?''', (ktoNum_handy,))
    aktuellesKonto = cursor.fetchone()

    if aktuellesKonto == None:

        client.send("false")
        print 'Bitte erstmal ein Konto am PC anlegen\n'

    else:

        ktoNum = aktuellesKonto[0]
        vorName = set(aktuellesKonto[1].split(' '))
        nachName = set(aktuellesKonto[2].split(' '))
        gebDat = set(aktuellesKonto[3].split(' '))
        pLz = aktuellesKonto[4]
        wohnOrt = set(aktuellesKonto[5].split(' '))

        if ( int(ktoNum) == int(ktoNum_handy) and vorName == vorName_handy and nachName == nachName_handy and gebDat == gebDat_handy and int(pLz) == int(pLz_handy) and wohnOrt == wohnOrt_handy):  #and str(vorName) is str(vorName_handy) and str(nachName) is str(nachName_handy) and str(gebDat) is str(gebDat_handy) and str(pLz) is str(pLz_handy) and str(wohnOrt) is str(wohnOrt_handy)

            now = datetime.datetime.now()
            currentTime = now.strftime("%d.%m.%Y, %H:%M:%S")
            serverNameDatum = "Stream "+str(kontakt)+(":\n---> DMD-Server ("+currentTime+")\n")
            client.send(serverNameDatum)

            print 'gleich'

        else:
            client.send("false")
            print 'nicht gleich\n'

    kontakt += 1

    client.close()

streamSock.close()

Socket socket = null;

try {

    SocketAddress sock_addresse = new InetSocketAddress(dstAddress, dstPort);
    socket = new Socket();
    socket.connect(sock_addresse, timeoutMs);

    //Senden
    JSONObject json = new JSONObject();

    try (OutputStreamWriter writer = new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8)){

        json.put("Konto",userKonto);
        json.put("Vorname",userVorname);
        json.put("Nachname",userNachname);
        json.put("Geburt",userGeburt);
        json.put("Plz",userPlz);
        json.put("Wohnort",userWohnort);
        writer.write(json.toString());

    } catch (JSONException e) {
        e.printStackTrace();
        failMessage = "Fehler JSON!" + e.toString();

    }finally {

        try {
            //response = "hallo";

            // von hier ...

            InputStream stream = new BufferedInputStream(socket.getInputStream());
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stream));
            StringBuilder builder = new StringBuilder();
            String inputString;
            while ((inputString = bufferedReader.readLine()) != null) {
                builder.append(inputString);
                response = builder.toString();

              //bis hier habe ich neu eingefügt. woraus der fehler entsteht

            }
        }catch (Exception e) {
            e.printStackTrace();
            failMessage = "Fehler INPUTSTRING!" + e.toString();  //<--- dieser fehler spricht an
        }
    }

} catch (UnknownHostException e) {
    e.printStackTrace();
    failMessage = "IP-ADRESSE UNBEKANNT!";

} catch (IOException e) {
    e.printStackTrace();
    failMessage = "PC NICHT ERREICHBAR!";
}finally{
    if(socket != null){
        try {
            socket.close();                                      // <--- und hier wird der socket geschlossen                    

        } catch (IOException e) {
            e.printStackTrace();
            failMessage = "IO-Exception: " + e.toString();
        }
    }
}

}
return null;

//Servernamen empfangen
ByteArrayOutputStream bAPS_Message = new ByteArrayOutputStream(1024);
byte[] bytes_Message = new byte[1024];
int int_Message;
InputStream input_Message = socket.getInputStream();
while(true) {
    int_Message = input_Message.read(bytes_Message);
    bAPS_Message.write(bytes_Message, 0, int_Message);
    response = bAPS_Message.toString("UTF-8");
}