Modify UI from Listener

Question

Recently I'm working on App, that show video stream from URL. After connecting to specified WiFi it should open WebView, and stream Video.

Problem is, that I need to check if we are using proper WiFi, then switch to new Activity. Listener, that checks it is creating own thread, and can't modify UI. I've tried runOnUiThread, but it still don't change the UI, I just get rid of Exceptions. Is there a way to make it working? My code:

public class MainActivity extends AppCompatActivity {

    ...
    private Boolean mStatus = Boolean.FALSE;
    private ConnectionHandler mConnectionStatus;
    ...

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ...
        mConnectionStatus = new ConnectionHandler();
        ...


        connectButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startLoadingScreen();
                connectToCamera(mWifiManager);
                new Thread(new ConnectivityStatus()).start();
            }
        });

        mConnectionStatus.addConnectivityListener(new ConnectionHandler.ConnectivityListener() {
            @Override
            public void onChange() {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        stopLoadingScreen();
                        openWebView();
                    }
                });
            }
        });

        final Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                if(!mConnectionStatus.getStatus()){
                    stopLoadingScreen();
                    Toast.makeText(getApplicationContext(),
                            "Camera not found.\nMake sure that camera is turned on.",
                            Toast.LENGTH_LONG).show();
                }
            }
        }, 30000);
    }

    public void stopLoadingScreen() {
        connectButton.setAlpha(1.0f);
        mTextView.setAlpha(1.0f);
        mLoadingView.setVisibility(View.GONE);
    }

    ...

    private void openWebView() {
        Intent intent = new Intent(this, WebViewActivity.class);
        startActivity(intent);
    }

    class ConnectivityStatus implements Runnable{
        @Override
        public void run(){

            long startTime = System.currentTimeMillis();
            if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                mPermissions = Boolean.FALSE;
            }
            WifiInfo wifiInfo = mWifiManager.getConnectionInfo();
            if (wifiInfo.getSupplicantState() == SupplicantState.COMPLETED) {
                while ((System.currentTimeMillis() - startTime) < 30000) {
                    if (wifiInfo.getSSID().equals(mSsid)) {
                        mConnectionStatus.setStatus(Boolean.TRUE);
                        break;
                    }
                }
            }
        }
    }

}

Answer 1

Try to use post() method from Handler. For example:

new Handler().post(runnable)