Android UI from other thread

Question

I'm creating an application that gets the get the homestatus from a server in json but this happens on another thread. this isn't a problem when i try to set most Items on the ui because i can set them in a static void. but when i try to create a new switch and space i can't call 'this' to create a new.

code for getting the homestatus:

public void loadHomeStatus()
{
    if(socket != null) {`enter code here`
        if (socket.isConnected()) {
            Log.d("BtnUpdate","already connected");
            return;
        }
    }

    swAlarm = (Switch) findViewById(R.id.swAlarmState);
    tvTemperature = (TextView) findViewById(R.id.tvTemprateur);
    tvHumidity = (TextView) findViewById(R.id.tvHumidity);
    llDevices = (LinearLayout) findViewById(R.id.llDevices);

    new Thread() {
        public void run() {
            try
            {
                busyConnecting = true;
                Log.d("loadHomeStatus","trying to connect to: " + host + ":" + port);
                 socket = new Socket(host, port);
                uiConnected();

                    Log.d("loadHomeStatus","Connected");
                    DataOutputStream os = new DataOutputStream(socket.getOutputStream());
                    DataInputStream is = new DataInputStream(socket.getInputStream());


                    os.writeBytes(password);
                    Log.d("Connect", "send: " + password);
                while (socket.isConnected()) {
                    byte[] data = new byte[500];
                    int count = is.read(data);
                    String recieved = new String(data).trim();
                    Log.d("loadHomeStatus","recieved " + recieved );
                    if(recieved.toLowerCase() == "failed")
                    {
                        Log.d("loadHomeStatus","failed to log in");
                    }
                    else
                    {
                        try
                        {
                            homeStatus = new Gson().fromJson(recieved, HomeStatus.class);
                            uiLoadStatus();
                        } catch (Exception e)
                        {
                            Log.d("Error", e.toString());
                        }
                    }
                }//end of while loop

                Log.w("loadHomeStatus", "end connection thread ");
                //ends thread
                Thread.currentThread().interrupt();
                return;
            }
            catch (UnknownHostException e)
            {
                e.printStackTrace();
                Log.w("loadHomeStatus", "no Failed to connect: " + host + "-" + 8001);
            }
            catch (IOException e)
            {
                e.printStackTrace();
                Log.w("loadHomeStatus", "no Failed to connect: " + host + "-" + 8001);
            }
            Log.w("loadHomeStatus","Connection ended");
            socket = null;
            busyConnecting = false;
            uiDisconnected();
        }
    }.start();
}`

Code for setting ui

public static void uiLoadStatus()
{
    if (homeStatus != null)
    {
            try {

                tvTemperature.post(new Runnable()
                {
                    public void run()
                    {
                        //Log.d("uiLoadStatus to string",homeStatus.toString());

                        tvTemperature.setText(homeStatus.temperature + "°C");
                        tvHumidity.setText(homeStatus.humidity + "%");
                    }
                });
        }
        catch(Exception e)
        {
            Log.d("uiLoadStatus status fragment", e.toString());
        }


        try {
            swAlarm.post(new Runnable()
            {
                public void run() {
                    swAlarm.setChecked(homeStatus.alarmState);
                }
            });
        }
        catch (Exception e)
        {
            Log.d("uiLoadStatus alarm fragment", e.toString());

        }
    }
    try {
        llDevices.post(new Runnable()
        {
            public void run() {
                uiLoadDevices(); //this gives and error because it's not static
            }
        });
    }
    catch (Exception e)
    {
        Log.d("uiLoadStatus alarm fragment", e.toString());

    }
}


public void uiLoadDevices()
{
    for (int i = 0; i < homeStatus.lstDevices.size(); i++) {

        String deviceAdd = homeStatus.lstDevices.get(i);
        Space  mySpace = new Space(this);
        Switch mySwitch = new Switch(this);

        mySpace.setMinimumHeight(50);
        mySwitch.setText(homeStatus.getName(deviceAdd));
        mySwitch.setChecked(homeStatus.getState(deviceAdd));
        mySwitch.setTextSize(18);

        LinearLayout.LayoutParams lp = new          LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,       LinearLayout.LayoutParams.WRAP_CONTENT);
        lp.gravity = Gravity.LEFT;

        llDevices.addView(mySpace, lp);
        llDevices.addView(mySwitch, lp);
    }
}

Answer 1

uiLoadStatus is a static method (not sure why or if it has to be without looking at all of your code) and therefore you cannot call non-static methods from within it, such as uiLoadDevices

I would advise taking a look at your code and update your uiLoadStatus to not be static if at all possible. Abusing static can lead to sloppy code.

Answer 2

You should use AsyncTask and put the network interaction part in the doInBackground() method. To update the UI components, implement those logics in the onPostExecute() method