Question

My app is using GridView to get image from JSON. Everything is ok but now I want to make it for loading more by clicking on button. I followed this tutorial Android ListView with Load More Button.
When I followed it, I used runOnUiThread(new Runnable() {
public void run() { } } in the doInBackground but it errors NetworkOnMainThreadException i knew this cuz I run it on UI thread. but when I remove runOnUiThread..., it errors also

How can I fix this error? full source http://pastie.org/5659969

01-10 14:39:14.970: E/AndroidRuntime(19609): FATAL EXCEPTION: AsyncTask #3
01-10 14:39:14.970: E/AndroidRuntime(19609): java.lang.RuntimeException: An error occured while executing doInBackground()
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.os.AsyncTask$3.done(AsyncTask.java:299)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.lang.Thread.run(Thread.java:856)
01-10 14:39:14.970: E/AndroidRuntime(19609): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4847)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.ViewRootImpl.invalidateChildInParent(ViewRootImpl.java:974)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.ViewGroup.invalidateChild(ViewGroup.java:4075)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.View.invalidate(View.java:10525)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.View.invalidate(View.java:10480)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.widget.ImageView.invalidateDrawable(ImageView.java:190)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.graphics.drawable.Drawable.invalidateSelf(Drawable.java:350)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.graphics.drawable.Drawable.setVisible(Drawable.java:546)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.widget.ImageView.onDetachedFromWindow(ImageView.java:1173)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.View.dispatchDetachedFromWindow(View.java:12096)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:2541)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.view.ViewGroup.removeAllViewsInLayout(ViewGroup.java:3828)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.widget.AbsListView.resetList(AbsListView.java:2130)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.widget.GridView.setAdapter(GridView.java:170)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at com.camitss.mcolle.CardActivity$LoadMore.doInBackground(CardActivity.java:254)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at com.camitss.mcolle.CardActivity$LoadMore.doInBackground(CardActivity.java:1)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at android.os.AsyncTask$2.call(AsyncTask.java:287)
01-10 14:39:14.970: E/AndroidRuntime(19609):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
01-10 14:39:14.970: E/AndroidRuntime(19609):    ... 5 more

AsyncTask when first load

// Download JSON in Background
public class DownloadJSONFileAsync extends AsyncTask<String, Void, Void> {
    String token = getIntent().getExtras().getString("token1");

    protected void onPreExecute() {
        super.onPreExecute();
        showDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
    }

    @Override
    protected Void doInBackground(String... params) {
        String url = "http://xxx.xxx.xxx/card/all/"+num_page+"/0/?token="+token;
        JSONArray data = null;

        try {

            JSONObject jsonObject = new JSONObject(getJSONUrl(url));
            MyArrList = new ArrayList<HashMap<String, Object>>();
            HashMap<String, Object> map;
            data = jsonObject.getJSONArray("data");

            for (int i = 0; i < data.length(); i++) {
                JSONObject c = data.getJSONObject(i);
                map = new HashMap<String, Object>();

                // Thumbnail Get ImageBitmap To Object
                map.put("cardimage", (String) c.getString("cardimage"));
                map.put("ImageThumBitmap",(Bitmap) loadBitmap(c.getString("cardimage")));
                map.put("categoryid", (String) c.getString("categoryid"));
                MyArrList.add(map);
            }

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return null;
    }

    protected void onPostExecute(Void unused) {
        ShowAllContent(); // When Finish Show Content
        dismissDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
        removeDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
    }

}

AsycTask when using button to click to load more

// load more

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

    String token = getIntent().getExtras().getString("token1");

    protected void onPreExecute() {
        super.onPreExecute();
        showDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
    }

    @Override
    protected Void doInBackground(String... params) {
                num_page += 1;
                String url = "http://xxx.xxx.xxx/card/all/"+num_page+"/0/?token="+token;
                JSONArray data = null;

                try {

                    JSONObject jsonObject = new JSONObject(getJSONUrl(url));

                    MyArrList = new ArrayList<HashMap<String, Object>>();
                    HashMap<String, Object> map;
                    data = jsonObject.getJSONArray("data");
                    for (int i = 0; i < data.length(); i++) {
                        JSONObject c = data.getJSONObject(i);
                        map = new HashMap<String, Object>();

                        // Thumbnail Get ImageBitmap To Object
                        map.put("cardimage", (String) c.getString("cardimage"));
                        map.put("ImageThumBitmap",(Bitmap) loadBitmap(c.getString("cardimage")));
                        map.put("categoryid", (String) c.getString("categoryid"));
                        MyArrList.add(map);
                    }

                    int currentPosition = gridView1.getFirstVisiblePosition();
                    ImageAdapter adapter = new ImageAdapter(CardActivity.this, MyArrList);
                    gridView1.setAdapter(adapter);
                    gridView1.setSelection(currentPosition + 1);

                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
        return null;
    }

    protected void onPostExecute(Void unused) {
        ShowAllContent();
        dismissDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
        removeDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
    }

}

Answer 1

You should probably move this code:

                int currentPosition = gridView1.getFirstVisiblePosition();
                ImageAdapter adapter = new ImageAdapter(CardActivity.this, MyArrList);
                gridView1.setAdapter(adapter);
                gridView1.setSelection(currentPosition + 1);

into the onPostExecute method, because it has to be run on UI thread