Activity is completely blank when ran - maybe as a result of internet permissions?

Question

I'm fairly new to java/android development so please bear with me.

I've created an app as part of a online course that should supposedly run a "Guess the celebrity game".

The issue is when i run my code the main activity is completely blank.

The strange part is that the app presented in the course runs without issue and i have followed the code word for word. I have managed to find one other candidate who has the same issue and cannot solve it.

There are no errors (that i can find) in the logs and i can't seem to find any posts with a similar issue.

This weird behaviour only occours when i add the following permission in the manifest xml:

<uses-permission android:name="android.permission.INTERNET" />

Screenshot of emulator (also tested on real device):

https://s9.postimg.org/su0gc58gf/Capture.png/

Code from MainActivity:

public class MainActivity extends Activity {

ArrayList<String> celebURLs = new ArrayList<String>();
ArrayList<String> celebNames = new ArrayList<String>();
int chosenCeleb = 0;
int locationOfCorrectAnswer = 0;
String[] answers = new String[4];

ImageView imageView;
Button button0;
Button button1;
Button button2;
Button button3;

public void celebChosen(View view) {

    if (view.getTag().toString().equals(Integer.toString(locationOfCorrectAnswer))) {

        Toast.makeText(getApplicationContext(), "Correct!", Toast.LENGTH_LONG).show();

    } else {

        Toast.makeText(getApplicationContext(), "Wrong! It was " + celebNames.get(chosenCeleb), Toast.LENGTH_LONG).show();

    }

    createNewQuestion();

}

public class ImageDownloader extends AsyncTask<String, Void, Bitmap> {


    @Override
    protected Bitmap doInBackground(String... urls) {

        try {

            URL url = new URL(urls[0]);

            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            connection.connect();

            InputStream inputStream = connection.getInputStream();

            Bitmap myBitmap = BitmapFactory.decodeStream(inputStream);

            return myBitmap;


        } catch (MalformedURLException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        }

        return null;
    }
}


public class DownloadTask extends AsyncTask<String, Void, String> {


    @Override
    protected String doInBackground(String... urls) {

        String result = "";
        URL url;
        HttpURLConnection urlConnection = null;

        try {

            url = new URL(urls[0]);

            urlConnection = (HttpURLConnection) url.openConnection();

            InputStream in = urlConnection.getInputStream();

            InputStreamReader reader = new InputStreamReader(in);

            int data = reader.read();

            while (data != -1) {

                char current = (char) data;

                result += current;

                data = reader.read();
            }

            return result;

        } catch (Exception e) {

            e.printStackTrace();

        }

        return null;
    }
}

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

    imageView = (ImageView) findViewById(R.id.imageView);
    button0 = (Button) findViewById(R.id.button1);
    button1 = (Button) findViewById(R.id.button2);
    button2 = (Button) findViewById(R.id.button3);
    button3 = (Button) findViewById(R.id.button4);

    DownloadTask task = new DownloadTask();
    String result = null;

    try {

        result = task.execute("http://www.posh24.com/celebrities").get();

        String[] splitResult = result.split("<div class=\"sidebarContainer\">");

        Pattern p = Pattern.compile("<img src=\"(.*?)\"");
        Matcher m = p.matcher(splitResult[0]);

        while (m.find()) {

            celebURLs.add(m.group(1));

        }

        p = Pattern.compile("alt=\"(.*?)\"");
        m = p.matcher(splitResult[0]);

        while (m.find()) {

            celebNames.add(m.group(1));

        }


    } catch (InterruptedException e) {

        e.printStackTrace();

    } catch (ExecutionException e) {

        e.printStackTrace();

    }

    createNewQuestion();

}

public void createNewQuestion() {

    Random random = new Random();
    chosenCeleb = random.nextInt(celebURLs.size());

    ImageDownloader imageTask = new ImageDownloader();

    Bitmap celebImage;

    try {

        celebImage = imageTask.execute(celebURLs.get(chosenCeleb)).get();

        imageView.setImageBitmap(celebImage);

        locationOfCorrectAnswer = random.nextInt(4);

        int incorrectAnswerLocation;

        for (int i = 0; i < 4; i++) {

            if (i == locationOfCorrectAnswer) {

                answers[i] = celebNames.get(chosenCeleb);

            } else {

                incorrectAnswerLocation = random.nextInt(celebURLs.size());

                while (incorrectAnswerLocation == chosenCeleb) {

                    incorrectAnswerLocation = random.nextInt(celebURLs.size());

                }

                answers[i] = celebNames.get(incorrectAnswerLocation);


            }


        }

        button0.setText(answers[0]);
        button1.setText(answers[1]);
        button2.setText(answers[2]);
        button3.setText(answers[3]);


    } catch (Exception e) {
        e.printStackTrace();
    }


}

}

Logs:

  08-21 20:47:46.778 835-835/? I/Choreographer: Skipped 37 frames!  The application may be doing too much work on its main thread.
08-21 20:47:49.283 421-519/? W/AudioTrack: AUDIO_OUTPUT_FLAG_FAST denied by client

                                           --------- beginning of system
08-21 20:47:49.335 421-434/? I/ActivityManager: START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.shenstone.guessthecelebrity2/.MainActivity (has extras)} from uid 10007 on display 0
08-21 20:47:49.614 421-433/? I/art: Background sticky concurrent mark sweep GC freed 10530(678KB) AllocSpace objects, 3(608KB) LOS objects, 12% free, 9MB/10MB, paused 4.358ms total 263.235ms
08-21 20:47:49.854 69-69/? I/art: Background concurrent mark sweep GC freed 794(33KB) AllocSpace objects, 0(0B) LOS objects, 90% free, 111KB/1135KB, paused 12.562ms total 112.418ms
08-21 20:47:49.945 421-1030/? I/ActivityManager: Start proc com.example.shenstone.guessthecelebrity2 for activity com.example.shenstone.guessthecelebrity2/.MainActivity: pid=3562 uid=10055 gids={50055, 9997, 3003} abi=armeabi-v7a
08-21 20:47:49.982 3562-3562/? I/art: Not late-enabling -Xcheck:jni (already on)
08-21 20:47:52.244 3562-3574/? W/art: Suspending all threads took: 12.799ms
08-21 20:47:52.262 3562-3574/? I/art: Background partial concurrent mark sweep GC freed 322(512KB) AllocSpace objects, 0(0B) LOS objects, 64% free, 555KB/1579KB, paused 14.923ms total 43.870ms
08-21 20:47:52.395 3562-3574/? I/art: Background sticky concurrent mark sweep GC freed 219(436KB) AllocSpace objects, 0(0B) LOS objects, 28% free, 1129KB/1579KB, paused 9.677ms total 22.436ms
08-21 20:47:52.534 3562-3574/? I/art: WaitForGcToComplete blocked for 10.763ms for cause Background
08-21 20:47:53.258 3562-3574/? I/art: Background sticky concurrent mark sweep GC freed 469(1634KB) AllocSpace objects, 0(0B) LOS objects, 58% free, 660KB/1599KB, paused 6.830ms total 31.639ms
08-21 20:47:56.495 3562-3573/? I/art: WaitForGcToComplete blocked for 21.032ms for cause HeapTrim
08-21 20:47:59.381 421-443/? W/ActivityManager: Launch timeout has expired, giving up wake lock!
08-21 20:48:00.154 3562-3574/? W/art: Suspending all threads took: 39.137ms
08-21 20:48:00.183 3562-3574/? I/art: Background partial concurrent mark sweep GC freed 108(3KB) AllocSpace objects, 57(862KB) LOS objects, 60% free, 663KB/1687KB, paused 41.100ms total 174.221ms
08-21 20:48:00.244 3562-3574/? W/art: Suspending all threads took: 10.311ms
08-21 20:48:00.255 3562-3574/? I/art: Background sticky concurrent mark sweep GC freed 53(1872B) AllocSpace objects, 30(451KB) LOS objects, 56% free, 728KB/1687KB, paused 12.216ms total 26.132ms
08-21 20:48:00.354 3562-3574/? W/art: Suspending all threads took: 9.038ms
08-21 20:48:00.415 3562-3574/? I/art: Background partial concurrent mark sweep GC freed 135(4KB) AllocSpace objects, 81(1221KB) LOS objects, 48% free, 1094KB/2MB, paused 12.238ms total 111.401ms

Any help would be much appreciated, thanks!

Most likely, both. That method waits for the task to return before processing anything so it freezes the UI. You almost never (if ever) want to use that. — codeMagic, Aug 21 '16 at 20:52
Could you give me some advice on how to achieve the same result a better way? — AngryMan Studios, Aug 21 '16 at 20:55
[The end of this answer](http://stackoverflow.com/questions/18898039/using-asynctask/18898105#18898105) discusses it. You want to use `onPostExecute()` to assign the result to the variable you need. — codeMagic, Aug 21 '16 at 20:58
After about 15 mins of loading on my crappy emulator it finally loaded. That's very helpful advice, thanks! — AngryMan Studios, Aug 21 '16 at 21:02

score 0 · Answer 1 · answered Aug 21 '16 at 21:06

0

You are using the AsyncTask but did not started it. Use execute() method to start your async task.

answered Aug 21 '16 at 21:06

rahul

208
1
7

It's executed here: ' result = task.execute("http://www.posh24.com/celebrities").get(); ' – AngryMan Studios Aug 22 '16 at 10:58

Activity is completely blank when ran - maybe as a result of internet permissions?

1 Answers1