Android Parse.com检索图像列表

下面是我使用parse.com API的类

 public class ListActivity extends AppCompatActivity {
        RecyclerView recyclerView;
        LinearLayoutManager manager;
        List<Recipe> recipes;

    static int count = 0;

    private ProgressDialog progressDialog;

    NetworkInfo mWifi;
    ConnectivityManager connManager;
    NetworkInfo mInternet;

    Bitmap bmp;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        recipes = new ArrayList<Recipe>();
        connManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        mWifi = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
        mInternet = connManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
        //Parse.enableLocalDatastore(getApplicationContext());

        // Enable Local Datastore.
        if(mWifi.isConnected() && count == 0 || mInternet.isConnected() && count == 0) {

            //Parse.initialize(getApplicationContext(), "1", "2");
            ParseQuery<ParseObject> query = ParseQuery.getQuery("Recipes");
            progressDialog = ProgressDialog.show(ListActivity.this, "",
                    "Update", true);

            query.findInBackground(new FindCallback<ParseObject>() {
                public void done(List<ParseObject> recipesList, ParseException e) {
                    if (e == null) {

                        ParseObject.pinAllInBackground(recipesList);
                        Log.d("score", "Retrieved " + recipesList.size() + " recipes");
                        for (ParseObject obj : recipesList) {
                            ParseFile image = (ParseFile) obj.get("Picture");
                            image.getDataInBackground(new GetDataCallback() {
                                public void done(byte[] data, ParseException e) {
                                    if (e == null) {
                                        bmp = BitmapFactory.decodeByteArray(data, 0, data.length);
                                    } else {
                                        Log.d("mytag","coldnt load picture");
                                    }
                                }
                            });
                            initializeData(obj, bmp);
                        }
                    } else {
                        Log.d("score", "Error: " + e.getMessage());
                    }
                    initializeAdapter();
                    progressDialog.dismiss();
                }
            });
            count++;
        }if(!mWifi.isConnected() && !mInternet.isConnected() || count != 0) {//error on image

            ParseQuery<ParseObject> query = ParseQuery.getQuery("Recipes");
            query.fromLocalDatastore();
            query.findInBackground(new FindCallback<ParseObject>() {

                @Override
                public void done(List<ParseObject> list, ParseException e) {
                    if(e == null){
                        Log.d("score", "Retrieved " + list.size() + " recipes");
                        for(ParseObject obj : list){
                            initializeData(obj,bmp);
                        }
                    }else {
                        Log.d("score", "Error: " + e.getMessage());
                    }
                    initializeAdapter();
                }
            });
        }


        setContentView(R.layout.activity_main);
        recyclerView = (RecyclerView)findViewById(R.id.recyclerView);
        manager = new LinearLayoutManager(getApplicationContext());
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(manager);

        //added to avoid no adapter set exception
        recipes = new ArrayList<>();
        RVAdapter adapter = new RVAdapter(recipes);
        recyclerView.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    }

    @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 initializeAdapter(){
        RVAdapter adapter = new RVAdapter(recipes);
        recyclerView.setAdapter(adapter);
    }
    private void initializeData(ParseObject obj,Bitmap bmp){
        recipes.add(new Recipe(obj.getString("Description"), obj.getString("shortDescription"), obj.getString("Name"), bmp));
        Log.d("score", Integer.toString(recipes.size()));
    }
}
                 }

---

IMO u在初始化数据（obj、bmp）方面存在asnyc问题；因为它和内部回调不协调，内部回调等待内部查询提供位图实例的数据。正如我看到的那样，在异步从解析查询返回数据以获取文件之前，您正在尝试实例化位图。第二对对象应该带有图像，但实际上所有列表项中都没有图像。但我会试试您的想法。我会看到的。

I add my debug log to make you see what is going on.
08-30 18:14:01.943  31442-31442/by.test.roma.myapplication D/score﹕ 1
08-30 18:14:01.943  31442-31442/by.test.roma.myapplication D/score﹕ 2
08-30 18:14:02.088  31442-31442/by.test.roma.myapplication D/OpenGLRenderer﹕ Flushing caches (mode 0)
08-30 18:14:02.488  31442-31443/by.test.roma.myapplication D/dalvikvm﹕ GC_CONCURRENT freed 264K, 8% free 13277K/14279K, paused 28ms+3ms
08-30 18:14:03.113  31442-31442/by.test.roma.myapplication D/score﹕ Retrieved 2 recipes
08-30 18:14:03.403  31442-31443/by.test.roma.myapplication D/dalvikvm﹕ GC_CONCURRENT freed 367K, 8% free 13376K/14471K, paused 36ms+17ms
08-30 18:14:03.553  31442-31442/by.test.roma.myapplication D/picture﹕ 7345
08-30 18:14:03.608  31442-31442/by.test.roma.myapplication D/score﹕ 3
08-30 18:14:03.613  31442-31442/by.test.roma.myapplication D/picture﹕ 7345
08-30 18:14:03.653  31442-31442/by.test.roma.myapplication D/dalvikvm﹕ GC_FOR_ALLOC freed 79K, 8% free 13435K/14599K, paused 40ms
08-30 18:14:03.658  31442-31442/by.test.roma.myapplication D/score﹕ 4