Android NetworkOnMainThreadException in Background Methods

Question

I have some network requests in my app, and whenever the network related code is called, I got this exception. I already put them in background:

    @Background
    protected void getBitmapFromURL(String src, ImageView img) {
        try {
            URL url = new URL(src);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setDoInput(true);
            connection.connect();
            InputStream input = connection.getInputStream();
            updateImageView(BitmapFactory.decodeStream(input), img);
            return;
        } catch (IOException e) {
            System.out.println("************** network exception: download image failed");
            return;
        }
    }

    @UiThread
    protected void updateImageView(Bitmap bitmap, ImageView img) {
        img.setImageBitmap(bitmap);
        return;
    }

But the error still exists. I'm implementing my own adapter here, which extends BaseAdapter. I annotated it with @EBean and declared with @Bean in my activity file. The constructor only takes Context parameter, I put the initialization of other parameters in a separate method.

So I think the setup satisfies the requirements of androidannotation, and if the network operations are done in the background, why should this error occur?

The class I'm extending:

@EBean
public class MomentViewAdapter extends BaseAdapter {
    protected LayoutInflater mInflater;
    protected Context mContext;
    protected List<FavoriteInfo> mDatas;
    protected  int mItemLayoutId;

    public MomentViewAdapter(Context context) {
        this.mContext = context;
//        this.mInflater = LayoutInflater.from(mContext);
//        this.mDatas = mDatas;
//        this.mItemLayoutId = itemLayoutId;
    }

    public void setUp(List<FavoriteInfo> mDatas, int itemLayoutId) {
        this.mInflater = LayoutInflater.from(mContext);
        this.mDatas = mDatas;
        this.mItemLayoutId = itemLayoutId;
    }


    @Override
    public int getCount()
    {
        return mDatas.size();
    }

    @Override
    public FavoriteInfo getItem(int position)
    {
        return mDatas.get(position);
    }

    @Override
    public long getItemId(int position)
    {
        return position;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {

        if(convertView == null) {
            convertView = LayoutInflater.from(mContext).inflate(mItemLayoutId, parent, false);
        }
        ImageView img = (ImageView) convertView.findViewById(R.id.detail_moment_camera_picture);
        if (mDatas.get(position).isVideoFavorite()) {
            Bitmap bitmap = ThumbnailUtils.createVideoThumbnail(mDatas.get(position).getVideoURL(), MediaStore.Video.Thumbnails.MINI_KIND);
            img.setImageBitmap(bitmap);
        } else {
            getBitmapFromURL(mDatas.get(position).getImageURL(), img);
            // img.setImageBitmap(getBitmapFromURL(mDatas.get(position).getImageURL()));
        }
        img.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(mContext, GeneratedClassUtils.get(MomentDetailActivity.class));
                Bundle mBundle = new Bundle();
                mBundle.putSerializable(FavoriteInfo.KEY, mDatas.get(position));
                mBundle.putBoolean(CollectionInfo.KEY_WATCH_FLAG, false);
                intent.putExtras(mBundle);
                mContext.startActivity(intent);
            }
        });

        return convertView;

    }

StackTrace (error is in MomentViewAdapter):

09-02 11:35:17.302  30956-30956/com.bloomsky.bloomsky E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.bloomsky.bloomsky, PID: 30956
    android.os.NetworkOnMainThreadException
            at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)
            at libcore.io.BlockGuardOs.recvfrom(BlockGuardOs.java:249)
            at libcore.io.IoBridge.recvfrom(IoBridge.java:553)
            at java.net.PlainSocketImpl.read(PlainSocketImpl.java:485)
            at java.net.PlainSocketImpl.access$000(PlainSocketImpl.java:37)
            at java.net.PlainSocketImpl$PlainSocketInputStream.read(PlainSocketImpl.java:237)
            at com.android.okio.Okio$2.read(Okio.java:113)
            at com.android.okio.RealBufferedSource.indexOf(RealBufferedSource.java:147)
            at com.android.okio.RealBufferedSource.readUtf8LineStrict(RealBufferedSource.java:94)
            at com.android.okhttp.internal.http.HttpConnection.readResponse(HttpConnection.java:175)
            at com.android.okhttp.internal.http.HttpTransport.readResponseHeaders(HttpTransport.java:101)
            at com.android.okhttp.internal.http.HttpEngine.readResponse(HttpEngine.java:616)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:379)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:323)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:190)
            at com.bloomsky.android.ui.adapter.MomentViewAdapter.getBitmapFromURL(MomentViewAdapter.java:132)
            at com.bloomsky.android.ui.adapter.MomentViewAdapter.getView(MomentViewAdapter.java:85)
            at android.widget.AbsListView.obtainView(AbsListView.java:2346)
            at android.widget.GridView.makeAndAddView(GridView.java:1433)
            at android.widget.GridView.makeRow(GridView.java:361)
            at android.widget.GridView.fillDown(GridView.java:302)
            at android.widget.GridView.fillFromTop(GridView.java:437)
            at android.widget.GridView.layoutChildren(GridView.java:1276)
            at android.widget.AbsListView.onLayout(AbsListView.java:2150)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
            at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
            at android.widget.ScrollView.onLayout(ScrollView.java:1502)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
            at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at in.srain.cube.views.ptr.PtrFrameLayout.layoutChildren(PtrFrameLayout.java:247)
            at in.srain.cube.views.ptr.PtrFrameLayout.onLayout(PtrFrameLayout.java:216)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1077)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
            at com.bloomsky.android.ui.SwipeBackLayout.onLayout(SwipeBackLayout.java:233)
            at android.view.View.layout(View.java:15604)
            at android.view.ViewGroup.layout(ViewGroup.java:4967)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
            at android.view.View.layout(View.java:15604

And as requested, here is the related activity code:

        @Bean
        MomentViewAdapter mGridViewAdapter;mGridViewAdapter = new MomentViewAdapter(this);
        mGridViewAdapter.setUp(mMomentDatas, R.layout.device_detail_moment_listitem_simple);
        mGridView.setAdapter(mGridViewAdapter);

Please post your stack trace, and show where you are invoking `getBitmapFromURL()`. You might also consider using one of the seemingly infinite number of [image loading libraries for Android](https://android-arsenal.com/tag/46), as they have already solved this problem. — CommonsWare, Sep 02 '15 at 18:55
@MarkGilchrist I think so. The androidannotations should have taken care of it. — J Freebird, Sep 02 '15 at 19:11
@CommonsWare I added the stack trace. I'm invoking the method in the getView method of my custom adapter. — J Freebird, Sep 02 '15 at 19:13
@JFreebird I think that is where you are going wrong, I am sure they wont answer below looks very good — Mark Gilchrist, Sep 02 '15 at 19:13
I haven't used AndroidAnnotations. The examples of `@Background` that I see are in activities, so perhaps there is some limitation on the classes that can use that annotation. — CommonsWare, Sep 02 '15 at 19:17
Post your Activity and the Manifest (where you declare the Activity) — Gabriele Mariotti, Sep 02 '15 at 19:56
@CommonsWare there is no such limitation. *AndroidAnnotations* adds compile time errors in case of those. :) — WonderCsabo, Sep 02 '15 at 20:35
Did you declare @EActivity in your Activity and register the Activity with "_" in your manifest ? — Gabriele Mariotti, Sep 02 '15 at 20:50
@GabrieleMariotti Yes, I've used AA for some time, and now I'm just adding some more functionality to an old code base. — J Freebird, Sep 02 '15 at 21:06

Jorge Casariego · Answer 1 · 2015-09-02T19:39:15.163

Try to do it this way

    ImageView imageView;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        imageView = (ImageView) findViewById(R.id.imageView);

        // Create an object for subclass of AsyncTask
        BitmapDownloaderTask task = new BitmapDownloaderTask();
         .
         .
         .        

    }

class BitmapDownloaderTask extends AsyncTask<String, Void, Bitmap> {
.
.
.

@Override
// Actual download method, run in the task thread
protected Bitmap doInBackground(String... params) {
     return getBitmapFromURL(params...);
}

@Override
// Once the image is downloaded, associates it to the imageView
protected void onPostExecute(Bitmap bitmap) {
    if (isCancelled()) {
        bitmap = null;
    }
        if (imageView != null) {
            imageView.setImageBitmap(bitmap);
        }
 }
}


protected void getBitmapFromURL(String src) {
        try {
            URL url = new URL(src);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setDoInput(true);
            connection.connect();
            InputStream input = connection.getInputStream();

            //New Line added
            final Bitmap bitmap = BitmapFactory.decodeStream(input);

            //return bitmap
            return bitmap;
        } catch (IOException e) {
            System.out.println("************** network exception: download image failed");
            return;
        }
    }

But instead of doing in this way I would recommend you the use of Volley.

The Volley introduction looks very powerful. I'm gonna learn the docs and give it a try. So you think androidannotations is not working properly here? — J Freebird, Sep 02 '15 at 19:17
@JFreebird I edited my answer. That was a code of a old project I had so I deleted some code now — Jorge Casariego, Sep 02 '15 at 19:35
@Jorge Casariego the purpose of `@Background` is to eliminate the `AsyncTask` boilerplate actually. — WonderCsabo, Sep 02 '15 at 20:34
@JorgeCasariego I cannot access the imageView, unless passed in as a parameter, but the Asynctask methods can only take parameters of the same type. — J Freebird, Sep 02 '15 at 20:50

score 2 · Accepted Answer · answered Sep 02 '15 at 20:33

2

The problem here is you are not using the generated class, but your annotated one which of course does not contain any enhancements. You have to create or inject your enhanced adapter to the class where you want to use it, then call the background method on that instance.

@EActivity
public class YourActivity {

  @Bean // will inject instance of generated MomentViewAdapter_
  MomentViewAdapter adapter;

  @AfterInject // injected beans are only available from here
  public void afterInject() {
     yourList.setAdapter(adapter);
  }
}

answered Sep 02 '15 at 20:33

WonderCsabo

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I got: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.GridView.setAdapter(android.widget.ListAdapter)' on a null object reference at com.bloomsky.android.activities.common.DeviceDetailActivity.afterInject(DeviceDetailActivity.java:626) – J Freebird Sep 02 '15 at 21:02
so it says 'adapter' is null. But I did use: @AfterInject // injected beans are only available from here public void afterInject() { mGridViewAdapter.setUp(mMomentDatas, R.layout.device_detail_moment_listitem_simple); mGridView.setAdapter(mGridViewAdapter); } and annotated it with \@Bean – J Freebird Sep 02 '15 at 21:03
Actually I've used EBean for some time, but I never used the AfterInject annotation. All my previous codes run perfect without it. I thought the instance is automatically created once you used @Bean – J Freebird Sep 02 '15 at 21:05
The NPE: if you inject the `GridView`, you have to use `@AfterViews`, instead of `@AfterInject.` – WonderCsabo Sep 02 '15 at 22:18
Of course an instance is not created. You have to inject an instance, like i said. But you also created an instance, i guess you just used `new MomentViewAdapter()`, which created an instance of the not-enhanced class.. – WonderCsabo Sep 02 '15 at 22:20
Sorry, that is old cold. I didn't have new MomentViewAdapter(). Actually the method with \@AfterInject is called inside another method with \@AfterViews. – J Freebird Sep 02 '15 at 23:11
But the setUp method of that instance did not throw any errors, although it is called before setAdapter, which is confusing to me. – J Freebird Sep 02 '15 at 23:13
The mGridView field is null, when you call setAdapter on it, that is the problem. This means you forgot to instantiate that field, or you use it too early. – WonderCsabo Sep 03 '15 at 05:43
Yes, when I deleted @afterInject, it worked. I think this decorator injects both the views and the enhanced classes. Thanks. – J Freebird Sep 03 '15 at 16:59
Yes. In `@AfterInject` annotated methods injected prefs, resources, beans are available. In `@AfterViews` annotated methods, also views are available. – WonderCsabo Sep 03 '15 at 17:04

Android NetworkOnMainThreadException in Background Methods

2 Answers2