在第二次编译后，Listview不会出现在Fragment中

Question

Listview在第二次编译后没有出现在Fragment中。 片段中的按钮有效，所以问题出在listview和适配器上，但我无法理解问题所在。

即使我删除程序并重新安装，也无济于事。只有移动其他位置方法updatepost，它才能工作一次。 希望有所建议！我只是在学习这一切。

主要片段：

public class MainFragment extends Fragment {

ArrayList<Bitmap> bitArray;
CustomListAdapter adapter;

public MainFragment() {
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

}

@Override
public void onStart() {
    super.onStart();}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main, container, false);
    ListView listview = (ListView)rootView.findViewById(R.id.listViewPost);
    Log.v("Plaxehere","1");
        adapter = new CustomListAdapter(getContext(), bitArray);
        listview.setAdapter(adapter);

        listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
                Toast.makeText(getActivity(), "YESS", Toast.LENGTH_SHORT).show();
            }
        });


    Button but =(Button) rootView.findViewById(R.id.button_back_to_home);
    but.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v) {
            Toast.makeText(getContext(), "Text", Toast.LENGTH_SHORT).show();
            /*Intent intent = new Intent(getActivity(), MainActivity.class).putExtra(Intent.EXTRA_TEXT, "Hello");
            startActivity(intent);*/
        }
    });

    return rootView;
}


private void updatePost() {

    FetchPosterTask postTask = new FetchPosterTask(getActivity());
    postTask.execute("uk_news.json");

}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    bitArray = new ArrayList<>();
    updatePost();

}

class FetchPosterTask extends AsyncTask<String, Void, ArrayList<Bitmap>> {
    private final String LOG_TAG = FetchPosterTask.class.getSimpleName();
    private Context context;


    public FetchPosterTask (Context myContext) {
        this.context = myContext;
    }

    @Override
    protected ArrayList<Bitmap> doInBackground(String... params) {

        if(params.length ==0 ){
            return null;
        }

        String json = null;

        try {
            json = getJson(params[0]);

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

        try {
            String[] masPst = getPosterfromJsonAsString(json);
            ArrayList<Bitmap> result =decodeImageToBitmap(masPst);

            return result;
        }catch (JSONException e){
            Log.e(LOG_TAG, "Place 5", e);
        }

        return null;
    }

    private String getJson(String filename) throws IOException{
        InputStream is = this.context.getAssets().open(filename);
        int size = is.available();
        byte[] buffer = new byte[size];
        is.read(buffer);
        is.close();
        return new String(buffer);

    }

    private String[] getPosterfromJsonAsString(String posterJson) throws JSONException {
        final String OWM_NFO = "nfo";
        final String OWM_NWS = "nws";
        final String OWM_PST = "pst";


        JSONObject imageJson = new JSONObject(posterJson);
        JSONObject nfoArray = imageJson.getJSONObject(OWM_NFO);
        JSONArray nwsArray = nfoArray.getJSONArray(OWM_NWS);

        String[] resultStr = new String[nwsArray.length()];

        for(int i =0; i<nwsArray.length(); i++){
            JSONObject pst = nwsArray.getJSONObject(i);
            String im = pst.getString(OWM_PST);

            resultStr[i] = im;
        }

        return resultStr;

    }


    public ArrayList<Bitmap> decodeImageToBitmap (String[] base64Image) {
        ArrayList<Bitmap> bitmapArrayList = new ArrayList<Bitmap>();
        for(int i =0; i<4; i++) {
            byte[] decodedString = Base64.decode(base64Image[i], Base64.DEFAULT);
            Bitmap base64Bitmap = BitmapFactory.decodeByteArray(decodedString, 0,
                    decodedString.length);
            bitmapArrayList.add(i, base64Bitmap);
        }
        return bitmapArrayList;
    }

    @Override
    protected void onPostExecute(ArrayList<Bitmap> bitmapArrayList) {
        if(bitArray.size()!=0){
            bitArray.clear();
            bitArray.addAll(bitmapArrayList);
        }
        else{
                bitArray.addAll(bitmapArrayList);

        }
    }
}


}

适配器

public class CustomListAdapter extends BaseAdapter {
private final String LOG_TAG = CustomListAdapter.class.getSimpleName();
private ArrayList<Bitmap> bitmapArrayList;
private LayoutInflater layoutInflater;

public CustomListAdapter(Context context, ArrayList<Bitmap> bitmapArrayList) {
    this.bitmapArrayList = bitmapArrayList;
    this.layoutInflater = LayoutInflater.from(context);
}

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

@Override
public Object getItem(int position) {
    return bitmapArrayList.get(position);
}
@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;

    if(convertView == null) {
        convertView = layoutInflater.inflate(R.layout.list_post_item, null);

        holder = new ViewHolder();
        holder.imageView = (ImageView) convertView.findViewById(R.id.list_item);
        convertView.setTag(holder);
        Log.v(LOG_TAG,"1");
    }
 else {
    holder = (ViewHolder) convertView.getTag();
        Log.v(LOG_TAG,"2");
}
    Log.v(LOG_TAG,"3");
    if(getItem(position) == null) {
        holder.imageView.setImageResource(R.drawable.pst_0);
        Log.v(LOG_TAG,"5");
    }
    else{
        holder.imageView.setImageBitmap((Bitmap) getItem(position));
        Log.v(LOG_TAG,"6");
    }
    Log.v(LOG_TAG,"4");

    return convertView;
}

static class ViewHolder {
    ImageView imageView;

}


}

主要活动

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new MainFragment())
                .commit();
    }

}

}