android 在 asynctask 中显示 dialogfragment

Question

我的 AsyncTask 中的对话框片段有一些问题。基本上这是发生的事情的要点。我有一个自定义列表适配器来构建 ListView。在执行前，我显示我的对话框。数据通过 doInBackground 加载到列表中。在 post 执行时，我关闭了我的对话框。问题是我现在只剩下一个空白屏幕。对话框出现然后消失，但没有项目列表。真的不确定发生了什么。这是我的 DialogFragment class:

public class ProcessingDialog extends DialogFragment {

    private String dialog_text;


    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the Builder class for convenient dialog construction
        final AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        // Get the layout inflater
        LayoutInflater inflater = getActivity().getLayoutInflater();

        View dialog_view = inflater.inflate(R.layout.dialog_loading, null);
        final TextView tv1 = (TextView) dialog_view.findViewById(R.id.dialog_text);
        dialog_text = getArguments().getString("message");
        tv1.setText(dialog_text);
        // Inflate and set the layout for the dialog
        // Pass null as the parent view because its going in the dialog layout

        builder.setView(dialog_view);

        // Create the AlertDialog object and return it
        return builder.create();
    }
}

这是我的 MainActivity：

public class MainActivity extends FragmentActivity {

    private Context context = this;
    private List<RandomdataModel> list;
    private LayoutInflater layoutInflater;
    private CustomListAdapter listAdapter;
    private ProcessingDialog dialog_fragment_loading;
    private MessageDialog dialog_fragment_message;

    private final String[] parts = new String[]{"Sprocket", "Screw", "Nail",
            "Widget", "Gear", "Cog", "Tube", "Spring", "Tape", "Bolt"};


    private static final String LOGTAG = "MainActivity";
    private static final boolean DEBUG = true;

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

        listAdapter = new CustomListAdapter(this);
        ListView listView = (ListView) this.findViewById(R.id.listView);
        listView.setAdapter(listAdapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View view, int position, long id) {
                if (DEBUG) {
                    Log.d(LOGTAG, "onItemClick(): arg0=" + arg0.getClass().getSimpleName());
                    Log.d(LOGTAG, "onItemClick(): arg1=" + view.getClass().getSimpleName());
                }

                TextView tv1 = (TextView) view.findViewById(R.id.listitemTextIDValue);
                TextView tv2 = (TextView) view.findViewById(R.id.listitemTextPartValue);
                RandomdataModel data = new RandomdataModel();

                data.setId(Integer.parseInt(tv1.getText().toString()));
                data.setPart(tv2.getText().toString());

                Intent intent = new Intent(context, DisplayActivity.class);
                intent.putExtra("data", data);

                if (intent.resolveActivity(getPackageManager()) != null) {
                    startActivity(intent);
                }
            }
        });
    }

    @Override
    public void onResume() {
        //called after onStart() just before activity comes to the foreground
        super.onResume();
        new UpdateList().execute();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    class CustomListAdapter
            extends BaseAdapter {
        private Context context;
        private List<RandomdataModel> list;
        private LayoutInflater layoutInflater;

        CustomListAdapter(Context context) {
            this.context = context;
        }

        public void setList(List<RandomdataModel> list) {
            this.list = list;
        }

        @Override
        public int getCount() {
            return ((list == null) ? 0 : list.size());
        }

        @Override
        public Object getItem(int position) {
            //  In theory we should not be called if getCount() returned 0;
            return list.get(position);
        }

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

        class ViewHolder {
            int position;
            TextView textView1;
            TextView textView2;
            Button button;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (DEBUG) {
                Log.d(LOGTAG, "getView.position=" + position);
                Log.d(LOGTAG, "getView.convertView=" + convertView);
            }
            if (list == null) {
                //  In theory it should not happen but handle this in some graceful way.
                //  Returning null will not produce graceful results.


                //display dialog of no data found....
                return null;
            }

            ViewHolder holder;

            if (convertView == null) {
                convertView = getLayoutInflator().inflate(R.layout.list_view_items, null);
                holder = new ViewHolder();
                holder.textView1 = (TextView) convertView.findViewById(R.id.listitemTextIDValue);
                holder.textView2 = (TextView) convertView.findViewById(R.id.listitemTextPartValue);
                holder.button = (Button) convertView.findViewById(R.id.listitemButton);
                holder.button.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {


                    }
                });
                convertView.setTag(holder);

            } else {
                holder = (ViewHolder) convertView.getTag();
            }

            RandomdataModel item = list.get(position);
            holder.textView1.setText("" + item.getId());
            holder.textView2.setText(item.getPart());
            holder.button.setText("Submit " + item.getId());

            return convertView;
        }

        private LayoutInflater getLayoutInflator() {
            if (layoutInflater == null) {
                layoutInflater = (LayoutInflater)
                        this.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            }
            return layoutInflater;
        }
    }

    class UpdateList
            extends AsyncTask<Void, Void, List<RandomdataModel>> {
        private final String LOGTAG = "Updating List";
        private final boolean DEBUG = true;
        private ProgressDialog dialog;


        @Override
        protected void onPreExecute() {
            //progressBarCircle.setVisibility(View.VISIBLE);
            dialog_fragment_loading = processingDialog("Loading Data...");
            dialog_fragment_loading.show(getSupportFragmentManager(), "loading_data");
        }

        @Override
        protected List<RandomdataModel> doInBackground(Void... params) {
            if (DEBUG) Log.d(LOGTAG, "**** doInBackground() STARTING");

            List<RandomdataModel> listData = new ArrayList<>();

            RandomdataModel data;

            int len = parts.length;
            try {
                Thread.sleep(4000);

                //loading data from array
                for (int i = 0; i < len; i++) {
                    data = new RandomdataModel();
                    data.setId(i);
                    data.setPart(parts[i]);
                    listData.add(data);
                }
            } catch (Exception e) {
                if (DEBUG) Log.d(LOGTAG, e.toString());
                e.printStackTrace();
            }

            return listData;
        }

        @Override
        protected void onPostExecute(List<RandomdataModel> listData) {
            //close dialog
            dialog_fragment_loading.dismiss();
            listAdapter.setList(listData);
        }
    }

    public static ProcessingDialog processingDialog(String message) {
        final ProcessingDialog f = new ProcessingDialog();
        final Bundle args = new Bundle();
        args.putString("message", message);
        f.setArguments(args);
        return f;
    }    
}

一直在搜索和搜索，只是没有运气，所以我想 post 我的问题在这里。任何帮助将不胜感激！

Answer 1

请在设置新列表后尝试调用listAdapter.notifyDataSetChanged()。

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