小编Rav*_*avi的帖子

我使用了 Paho Eclipse repo 中的 Android Service jar。在客户端连接后订阅任何主题时，我遇到了 NUllPOinterException。

    public void connect(View view) {

    MqttConnectOptions conOpt = new MqttConnectOptions();

    String uri = "tcp://" + host + ":" + port;
    boolean cleanSession = true;
    // int timeout = 60 ;
    // int keepalive = 60 ;
    clientHandle = uri + clientId;

    MqttAndroidClient client;
    client = Connections.getInstance(this)
            .createClient(this, uri, clientId);

    Connection conn = new Connection(clientHandle, clientId, host, port,
            this, client, sslConnection);

    conOpt.setCleanSession(cleanSession);
    // conOpt.setConnectionTimeout(timeout);
    conOpt.setKeepAliveInterval(100);;

    MqttCallbackHandler callback = new MqttCallbackHandler(this,
            MainActivity.this, clientHandle); …