[問題] progressBar+asyncTask(null reference)

[comteken ([CR])]

public class MorePhotoDialog extends DialogFragment {
        private static final String TAG = "MorePhotoDialog";
        private CustomAdapter _customAdapter;
        private Context _context;
        private ListView _listView;
        private LinearLayout _linearLayout;
        private ProgressBar _progressBar;

        public MorePhotoDialog(Context context) {
                Log.d(TAG, "new MorePhotoDialog");
                _customAdapter = new CustomAdapter(context);
                _context = context;
        }

        @Override
        public Dialog onCreateDialog(Bundle savedInstanceState) {
                LayoutInflater inflater = getActivity().getLayoutInflater();
                View view = inflater.inflate(R.layout.custom_adapter, null);
                _progressBar = (ProgressBar) view
                .findViewById(R.id.custom_adapter_progressBar2);

                _linearLayout = (LinearLayout) view
                                .findViewById(R.id.custom_adapter_progressLine);

                _listView = (ListView) view.findViewById(R.id.custom_adapter_listView);
                _listView.setAdapter(_customAdapter);

                AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
                builder.setView(view);
                builder.setTitle(R.string.more_photo_dialog_more);

                return builder.create();
        }

        int endFlag = 0;

        public void addImageLoaderTask(String... urls) {

                endFlag = urls.length - 1;
                for (int i = 0; i < urls.length - 1; i++) {
                        ImageLoaderTask imageLoaderTask = new ImageLoaderTask(i);
                        Log.d(TAG, "imageLoaderTask.execute: " + urls[i]);
                        imageLoaderTask.execute(urls[i]);
                }

        }

        // private class ImageLoaderTask extends AsyncTask<String, Void,
Bitmap[]> {
        private class ImageLoaderTask extends AsyncTask<String, Void, Void> {
                private int _flag = 0;
                private ProgressBar progressBar;

                public ImageLoaderTask(int flag) {
                        _flag = flag;
//                      progressBar = (ProgressBar)
getActivity().findViewById(R.id.custom_adapter_progressBar2);
                }

                @Override
                protected void onPreExecute() {
                        // TODO progress bar
                        // Display progress bar
                        if (_flag == 0) {
                                _linearLayout.setVisibility(View.VISIBLE);
//                              progressBar.setVisibility(View.VISIBLE);
                        }
                }

                @Override
                protected Void doInBackground(String... url) {
                        String imgUrl = url[0];
                        Log.w(TAG, "url[0] = " + url[0]);

                        // Getting Caching directory
                        File cacheDirectory = _context.getCacheDir();

                        // Temporary file to store the downloaded image
                        File tmpFile = new File(cacheDirectory.getPath(),
                                        FunctionUtility.getLastString(imgUrl));

                        Log.d(TAG, "imgUrl(" + tmpFile.getName() + ") = " + imgUrl);
                        if (!tmpFile.exists()) {
                                Log.w(TAG, tmpFile.getPath() + " not exists");
                                BitmapFuntions.downloadBitmapFromUrl(imgUrl, tmpFile);
                        }
                        // Load bitmap and put in adapter
                        Bitmap bitmap = BitmapFuntions.decodeFile(tmpFile, 300, 200);
                        _customAdapter.addBitmap(bitmap);

                        // Show Logs
                        Log.d(TAG, "bitmap.getByteCount() = " + bitmap.getByteCount());
                        Log.d(TAG, tmpFile.getPath());
                        Log.d(TAG, tmpFile.getName() + " = " + tmpFile.length() / 1024
                                        + " Kb");

                        return null;
                }

                @Override
                // protected void onPostExecute(Bitmap[] result) {
                protected void onPostExecute(Void result) {
                        Log.d(TAG, "onPostExecute");

                        _customAdapter.notifyDataSetChanged();


                        if (_flag == endFlag) {
                                _linearLayout.setVisibility(View.GONE);
                                //progressBar.setVisibility(View.GONE);
                        }

                }
        }
}


呼叫dialogFragment的方法是

                        // Show MorePhotoDialog
                        MorePhotoDialog morePhotoDialog = new MorePhotoDialog(
                                        Image_enlarge.this);
                        morePhotoDialog
                                        .show(getSupportFragmentManager(), "morePhotoDialog");

                        morePhotoDialog.addImageLoaderTask(imglist);



可是會跑出NullPointerException
07-24 14:59:22.000: E/AndroidRuntime(7064): java.lang.NullPointerException:
Attempt to invoke virtual method 'void android.view.View.setVisibility(int)'
on a null object reference
07-24 14:59:22.000: E/AndroidRuntime(7064):     at
com.gundam.cool.dialog.MorePhotoDialog$ImageLoaderTask.onPreExecute(MorePhotoDialog.java:96)
07-24 14:59:22.000: E/AndroidRuntime(7064):     at
android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
07-24 14:59:22.000: E/AndroidRuntime(7064):     at
android.os.AsyncTask.execute(AsyncTask.java:535)


不懂為什麼抓不到view...


--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 114.36.155.148
※ 文章網址: http://www.ptt.cc/bbs/AndroidDev/M.1406228461.A.A3C.html
推 markzog21:你把要顯示的view丟到asyncTask裡面去試試看
→ markzog21:要顯示dialog的view
試過了，也是一樣的結果

→ corrupt003:你的activity的layout裡有view叫
→ corrupt003:R.id.custom_adapter_progressBar2 嗎？
有，我是用alt+/找到的

※ 編輯: comteken (140.124.249.8), 07/26/2014 09:25:59
推 corrupt003:alt + / 是找到R.java的所有資料…你還是要看activity
→ corrupt003: 的layout 有沒有訂義這個id，因為你是用getActivity去
→ corrupt003:取得view的
推 freesamael:morePhotoDialog.show() 是 non-blocking call,
→ freesamael:FragmentManager 會排程到下一次 main thread 空閒時
→ freesamael:才把 DialogFragment 加到 activity。因此
→ freesamael:onCreateDialog() 被呼叫的時間會在
→ freesamael:addImageLoaderTask() 之後，此時 layout 還沒設定