图片未显示在 GridView 中

Question

我似乎无法弄清楚为什么我的 ImageView 没有填充到附加了自定义 ArrayAdapter 类的 GridView 中。

我试图根据 AsyncTask 调用填充图像，但我决定尝试将可绘制对象硬编码到正在使用的布局中的 ImageView 中，但它仍然没有显示任何内容。

我的实现有什么突出的地方吗？

我没有收到任何错误，我注意到的一件事是当我尝试调试时，它没有在 getView() 中遇到我的断点。

适配器类

public class MovieAdapter extends ArrayAdapter<Movie> {

    private LayoutInflater mInflater;

    public MovieAdapter(Context context, List<Movie> movies) {
        super(context, 0, movies);
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder vh;
        Movie movie = getItem(position);
        if(convertView == null){
            convertView = mInflater.inflate(R.layout.movie_item, parent, false);
            vh = new ViewHolder();
            vh.ivPoster = (ImageView) convertView.findViewById(R.id.ivMoviePoster);
            convertView.setTag(vh);
        } else {
            vh = (ViewHolder) convertView.getTag();
        }

        vh.ivPoster.setImageDrawable(getContext().getResources().getDrawable(R.drawable.ant_man));

        //Picasso.with(getContext()).load(movie.getFull_poster_path()).into(vh.ivPoster);
        return convertView;
    }

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

    @Override
    public int getPosition(Movie item) {
        return super.getPosition(item);
    }

    private class ViewHolder {
        private ImageView ivPoster;

    }
}

布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent" android:orientation="vertical">

    <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ant_man"
            android:id="@+id/ivMoviePoster"/>
</LinearLayout>

实施

public class MainActivity extends ActionBarActivity {

    private Spinner spinnerMovieSelection;
    private GridView gridViewMovie;
    private MovieAdapter movieAdapter;
    SortByAdapter sortByAdapter;
    private List<Movie> finalMovieList;
    private ImageView ivPoweredBy;
    private ArrayList<String> sortByList;

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

    private void init() {
        finalMovieList = new ArrayList<Movie>();
        sortByList = new ArrayList<String>();
        populateSortByList();

        gridViewMovie = (GridView) findViewById(R.id.gridViewMovie);
        spinnerMovieSelection = (Spinner) findViewById(R.id.spinnerMovieSelection);
        ivPoweredBy = (ImageView) findViewById(R.id.ivPoweredBy);


        sortByAdapter = new SortByAdapter(getApplicationContext(), sortByList);
        movieAdapter = new MovieAdapter(getApplicationContext(), finalMovieList);
        spinnerMovieSelection.setAdapter(sortByAdapter);
        gridViewMovie.setAdapter(movieAdapter);

        spinnerMovieSelection.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                getMovies((String) parent.getItemAtPosition(position));
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });
    }


    @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);
    }

    private void populateSortByList() {
        sortByList.add("Popularity");
        sortByList.add("Highest Rated");
    }

    private void getMovies(String sortBy) {
        Log.e("RANDOM TAG", "GET MOVIES CALLED");
        MovieAsyncTask movieAsyncTask = new MovieAsyncTask() {
            @Override
            public void onResponseReceived(List<Movie> movieList) {
                finalMovieList = movieList;
                movieAdapter.notifyDataSetChanged();
            }
        };
        movieAsyncTask.execute(sortBy);
    }
}

Answer 1

这里的重点是您的电影适配器中的列表始终为空。
您使用空列表初始化电影适配器。
然后在onResponseReceived 在getMovies 中，你分配finalMovieList = movieList; 然后notifyDatasetChanged，但是适配器仍然是空的，因为finalMoviewList 现在指向另一个引用
试试这个：

finalMovieList.clear();
if (movieList != null) {
  finalMovieList.addAll(movieList);
} 
movieAdapter.notifyDataSetChanged();

希望这会有所帮助。