Question

仅在活动第一次运行时填充ListView。重新创建活动后，不会填充列表。如果我从应用程序退出并再次打开它，它将无法正常工作。但是，如果我从任务菜单中删除它并再次打开它，它的工作原理。此外，ArrayAdapter在onResume和onImagesRetrieved中具有不同的count（getCount）。关于为什么会发生这种情况的任何想法？

public class GalleryActivity extends Activity implements ImagesDatabaseHelper.ImageDatabaseCallbacks {
    private static final int NUMEBR_OF_IMAGES = 10;
    private ArrayAdapter arrayAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gallery);
        arrayAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, new ArrayList());
        ((ListView)findViewById(R.id.lv_titles)).setAdapter(arrayAdapter);
    }

    @Override
    protected void onResume() {
        super.onResume();
        ImagesDatabaseHelper.getInstance(this, NUMEBR_OF_IMAGES).retrieveImages();
    }

    @Override
    public void onImagesRetrieved(List<Image> images) {
        Toast.makeText(this, "Successfully got " + images.size() + " images", Toast.LENGTH_LONG).show();
        arrayAdapter.clear();
        arrayAdapter.addAll(images);
        arrayAdapter.notifyDataSetChanged();
    }
}

Answer 1

试试这个，

public class GalleryActivity extends Activity implements ImagesDatabaseHelper.ImageDatabaseCallbacks {
    private static final int NUMEBR_OF_IMAGES = 10;
    private ArrayAdapter arrayAdapter;
    List<Image> dataset = new ArrayList();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gallery);
        arrayAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, dataset);
        ((ListView)findViewById(R.id.lv_titles)).setAdapter(arrayAdapter);
    }

    @Override
    protected void onResume() {
        super.onResume();
        ImagesDatabaseHelper.getInstance(this, NUMEBR_OF_IMAGES).retrieveImages();
    }

    @Override
    public void onImagesRetrieved(List<Image> images) {
        Toast.makeText(this, "Successfully got " + images.size() + " images", Toast.LENGTH_LONG).show();
        dataset.clear();
        dataset.addAll(images);
        arrayAdapter.notifyDataSetChanged();
    }
}

Answer 2

试试这个：

public class GalleryActivity extends Activity implements ImagesDatabaseHelper.ImageDatabaseCallbacks {
private static final int NUMEBR_OF_IMAGES = 10;
private ArrayAdapter arrayAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_gallery);
   ImagesDatabaseHelper.getInstance(this, NUMEBR_OF_IMAGES).retrieveImages();
}

@Override
protected void onResume() {
    super.onResume();
    ImagesDatabaseHelper.getInstance(this, NUMEBR_OF_IMAGES).retrieveImages();
}

@Override
public void onImagesRetrieved(List<Image> images) {
    Toast.makeText(this, "Successfully got " + images.size() + " images", Toast.LENGTH_LONG).show();
    arrayAdapter.clear();
    arrayAdapter.addAll(images);
     arrayAdapter = new ArrayAdapter(this,   android.R.layout.simple_list_item_1, images);
    ((ListView)findViewById(R.id.lv_titles)).setAdapter(arrayAdapter);
   // arrayAdapter.notifyDataSetChanged();
}
 }

Answer 3

将ArrayAdapter更改为静态字段可解决此问题。

重新启动Activity后，Android ListView不会填充

3 个答案: