Question

我使用async task获取数据，其中包含ImageUrl，title，rating，e.t.c等电影的详细信息。我为movie制作了一个电影课，我正在ImageUrl中加载gridView的图片。单击图像将导航到movie_detail_activity。
现在，当我最初运行应用程序时，单击图像导航到具有正确详细信息的活动，但是当我向下滚动然后向上滚动时，imageViews会自动更改，但详细信息活动保持原来的状态。

import...
public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        String url = "https://api.themoviedb.org/3/movie/top_rated?api_key=MY_KEY";
        new FetchPopularMoviesData().execute(url);
    }

    public void launch_activity(View view, MovieClass movie){
        Intent intent= new Intent(this,MovieDetails.class);
        Gson gson = new Gson();
        String movieJson = gson.toJson(movie);
        intent.putExtra("MovieJSON",movieJson);
        startActivity(intent);
    }
    public class FetchPopularMoviesData extends AsyncTask<String, Void, ArrayList<MovieClass>> {

        private Exception exception;         

        protected void onPreExecute() {


        }

        protected ArrayList<MovieClass> doInBackground(String... urls) {

            ArrayList<MovieClass> movies = new ArrayList<>();
            //code for fetching data from api
                return movies;              
        }

        protected void onPostExecute(final ArrayList<MovieClass> movies) {

            if (movies == null) {
                Log.e("After Parse Error", "No data found ,THERE WAS AN ERROR");

                Toast.makeText(getApplicationContext(), "No working internet connection", Toast.LENGTH_LONG).show();
            }
            else {
                for (int i = 0; i < movies.size(); i++) {
                    String title_name = movies.get(i).getTitle();
                    Log.i("INFO", title_name);
                }
                GridView gridview = (GridView) findViewById(R.id.gridview);
                gridview.setAdapter(new MovieAdapter(MainActivity.this, movies));

                gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                    public void onItemClick(AdapterView<?> parent, View v,
                                            int position, long id) {
                        launch_activity(v, movies.get(position));
                    }
                });
             }
    }    
}

以下是适配器的代码

public class MovieAdapter extends BaseAdapter {
    private Context mContext;
    private ArrayList<MovieClass> movies;

    public MovieAdapter(Context c,ArrayList<MovieClass> movies) {
        mContext = c;
        this.movies = movies;
    }

    public int getCount() {
        return movies.size();
    }

    public Object getItem(int position) {
        return null;
    }

    public long getItemId(int position) {
        return 0;
    }

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;
        if (convertView == null) {
            // if it's not recycled, initialize some attributes
            imageView = new ImageView(mContext);
            Picasso.with(mContext)
                    .load(movies.get(position).getPoster())
                    .into(imageView);
            imageView.setLayoutParams(new GridView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        } else {
            imageView = (ImageView) convertView;
        }

        return imageView;
    }
}

如何让ImageView与movie_details_activity内容保持同步？

Answer 1

public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    if (convertView == null) {
        // if it's not recycled, initialize some attributes
        imageView = new ImageView(mContext);
        imageView.setLayoutParams(new GridView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
    } else {
        imageView = (ImageView) convertView;
    }
    imageView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });

     Picasso.with(mContext)
                .load(movies.get(position).getPoster())
                .into(imageView);


    return imageView;
}

检查这是否可行。

Answer 2

使用ViewHolder。

这肯定会解决你的问题。希望它有所帮助。

private MovieClass mItem;//declare globally
 private ViewHolder holder;


 @Override
public View getView(int position, View convertView, ViewGroup parent)   {
    mItem = getItem(position);
    holder = null;
    if (convertView == null) {
        convertView = inflater
                .inflate(R.layout.row_fav_mem_list_item, null); //add imageview in this layout..
        holder = new ViewHolder(); //declare this globally
         holder.userPic = (ImageView) convertView
            .findViewById(R.id.img_user_pic);
        convertView.setTag(holder);
    }
       else
        holder = (ViewHolder) convertView.getTag();
        String imgURL = mItem.getPoster();
    if (!TextUtils.isEmpty(imgURL)) {
        imgLoader.load(imgURL).error(R.drawable.user_profile_image) //use default image if there is no image.
                .placeholder(R.drawable.user_profile_image)
                .into(holder.userPic);
    } else
        holder.userPic.setImageResource(R.drawable.user_profile_image);
    return convertView;
}

 public static class ViewHolder {
    ImageView userPic;
}

@Override
public MovieClass getItem(int position) {
    return movies.get(position);
}

Android：如何为gridView同步imageView和setOnItemClickListener

2 个答案: