java - ParseQueryAdapter 加载图像不正确

Question

我设置了 ParseQueryAdapter，但图像似乎没有正确加载。我总共有 10 个对象，最新的 3 个带有图像。

我的适配器正在使用适配器将所有这些对象拉入 ListView 中，但看起来不仅 3 个对象显示了图片，而且其他一些对象也在显示这些相同的图片，即使它们不是应该是因为没有对象的图像。

这可能是什么原因造成的？请注意，当我滚动底部的几项时，将交替拍摄列表中前三项的照片。

适配器

public class LocalSalesAdapter extends ParseQueryAdapter<Sale> {

    public LocalSalesAdapter(Context context) {
        super(context, new ParseQueryAdapter.QueryFactory<Sale>() {
            @SuppressWarnings("unchecked")
            public ParseQuery<Sale> create() {

                @SuppressWarnings("rawtypes")
                ParseQuery query = new ParseQuery("Sales");
                query.orderByDescending("createdAt");
                return query;
            }
        });
    }

    @Override
    public View getItemView(Sale sale, View v, ViewGroup parent) {

        if (v == null) {
            v = View.inflate(getContext(), R.layout.listview_local_sales_cell, null);
        }

        super.getItemView(sale, v, parent);

        ParseImageView saleImage = (ParseImageView) v.findViewById(R.id.icon);
        ParseFile photoFile = sale.getParseFile("photo");
        if (photoFile != null) {
            saleImage.setParseFile(photoFile);
            saleImage.loadInBackground(new GetDataCallback() {
                @Override
                public void done(byte[] data, ParseException e) {

                }
            });
        }

        TextView titleTextView = (TextView) v.findViewById(R.id.textView_listView_localSalesSubject);
        titleTextView.setText(sale.getSaleTitle());
        TextView descriptionTextView = (TextView) v.findViewById(R.id.textView_listView_localSalesDescription);
        descriptionTextView.setText(sale.getSaleDescription());
        TextView priceTextView = (TextView) v.findViewById(R.id.textView_listView_localSalesPrice);
        priceTextView.setText(sale.getSalePrice());
        return v;
    }

}

Activity

public class LocalSalesActivity extends ListActivity {
    ListView mLocalSales;

    ParseUser mCurrentUser;
    String mTAG = "LocalSalesActivity";

    private LocalSalesAdapter localSalesAdapter;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_local_sales);
        mLocalSales = (ListView) findViewById(android.R.id.list);
        localSalesAdapter = new LocalSalesAdapter(this);

        setListAdapter(localSalesAdapter);
    }

    @Override
    protected void onResume() {
        super.onResume();
        mCurrentUser = ParseUser.getCurrentUser();

    }
    @SuppressLint("InlinedApi")
    public void presentUserWithLogin() {
        // Displaying the Login Activity to the user
        Intent i = new Intent(this, LoginActivity.class);
        // Logging in =  New Task, Old Task = Clear so back button cannot be used to go back into Profile Activity if logged out.
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
        startActivity(i);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.local_sales, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) 
        {
        case R.id.action_log_out:
            // Logging out the current user and presenting them with the login activity.
            ParseUser.logOut();
            presentUserWithLogin();
            break;
        case R.id.action_post_sale:
            // Launching new intent to start Post Sale Activity
            Intent i = new Intent(this, PostSaleActivity.class);
            startActivity(i);
            break; 
        case R.id.action_profile_activity:
            finish();
        }
        return super.onOptionsItemSelected(item);
    }
}

Answer 1

如果 photoFile == null，您必须以某种方式清除 ParseImageView。例如将透明色设置为图像资源。因此，按以下方式修改 LocalSalesAdapter 类的 getItemView(...) 方法:

@Override
public View getItemView(Sale sale, View v, ViewGroup parent) {

    ...

    ParseImageView saleImage = (ParseImageView) v.findViewById(R.id.icon);
    ParseFile photoFile = sale.getParseFile("photo");
    if (photoFile != null) {
        saleImage.setParseFile(photoFile);
        saleImage.loadInBackground(new GetDataCallback() {
            @Override
            public void done(byte[] data, ParseException e) {
            }
        });
    } else { // Clear ParseImageView if an object doesn't have a photo
        saleImage.setImageResource(android.R.color.transparent);
    }

    ...
}