GridView：GridView没有更新

Question

删除某些文件后，我遇到更新gridView的问题。我一直在寻找解决方案几天但仍然无法解决问题。代码工作正常，所有缩略图都非常流畅，除非删除某些文件，gridView上没有任何更改。通过一些阅读，必须使用notifyDataSetChange()。但我不太清楚如何使用它以及在哪里使用它。

这就是我所拥有的：

public class ImageGridActivity extends Activity{
Cursor cursor;
private GridView mGridView;
ImageAdapter adapter;
private ArrayList<ImageViewInfo> videoRows;


@SuppressWarnings("deprecation")
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.images_layout);




String[] thumbColumns = { MediaStore.Images.Thumbnails.DATA,
        MediaStore.Images.Thumbnails.IMAGE_ID };

    String[] mediaColumns = { MediaStore.Images.Media._ID,
        MediaStore.Images.Media.DATA, MediaStore.Images.Media.TITLE,
        MediaStore.Images.Media.MIME_TYPE };

    cursor = managedQuery(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
        mediaColumns, null, null, null);

    videoRows = new ArrayList<ImageViewInfo>();

    if (cursor.moveToFirst()) {
      do {

        ImageViewInfo newVVI = new ImageViewInfo();
        int id = cursor.getInt(cursor.getColumnIndex(MediaStore.Images.Media._ID));
        Cursor thumbCursor = managedQuery(
            MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI,
            thumbColumns, MediaStore.Images.Thumbnails.IMAGE_ID
                + "=" + id, null, null);
        if (thumbCursor.moveToFirst()) {
          newVVI.thumbPath = thumbCursor.getString(thumbCursor
              .getColumnIndex(MediaStore.Images.Thumbnails.DATA));
          Log.v("", newVVI.thumbPath);
        }

        newVVI.filePath = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA));
        newVVI.title = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.TITLE));
        Log.v("", newVVI.title);
        newVVI.mimeType = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.MIME_TYPE));
        Log.v("", newVVI.mimeType);
        videoRows.add(newVVI);
      } while (cursor.moveToNext());
    }


    adapter = new ImageAdapter(this, videoRows);
    mGridView = (GridView)findViewById(R.id.gridview5);
    mGridView.setAdapter(adapter);


mGridView.setOnItemClickListener(new OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, View v, final int position, long id) {


        //Toast.makeText(ImageGridActivity.this, "" + position, Toast.LENGTH_SHORT).show();
        /*
        if (cursor.moveToPosition(position)) {
              int fileColumn = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
              int mimeColumn = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.MIME_TYPE);
              String videoFilePath = cursor.getString(fileColumn);
              String mimeType = cursor.getString(mimeColumn);
              Intent intent = new Intent(android.content.Intent.ACTION_VIEW);
              File newFile = new File(videoFilePath);
              intent.setDataAndType(Uri.fromFile(newFile), mimeType);
              startActivity(intent);
            }
            */
        final CharSequence[] items = {
                "Open", "Upload","Delete", "Properties"
        };

        AlertDialog.Builder builder = new AlertDialog.Builder(ImageGridActivity.this);
        builder.setTitle("Make your selection");
        builder.setItems(items, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int item) {
                // Do something with the selection
                //mDoneButton.setText(items[item]);
                if(items[item].equals("Open"))
                {
                    if (cursor.moveToPosition(position)) {
                      int fileColumn = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                      int mimeColumn = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.MIME_TYPE);
                      String videoFilePath = cursor.getString(fileColumn);
                      String mimeType = cursor.getString(mimeColumn);
                      Intent intent = new Intent(android.content.Intent.ACTION_VIEW);
                      File newFile = new File(videoFilePath);
                      intent.setDataAndType(Uri.fromFile(newFile), mimeType);
                      startActivity(intent);
                    }



                }
                else if(items[item].equals("Delete"))
                {
                    if (cursor.moveToPosition(position)) {
                          int fileColumn = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                          String videoFilePath = cursor.getString(fileColumn);
                          File newFile = new File(videoFilePath);                 
                          newFile.delete();
                        }
                        //ImageAdapter adapter = new ImageAdapter(ImageGridActivity.this,videoRows);
                        //adapter.notifyDataSetChanged();
                        mGridView.invalidateViews();
                        mGridView.setAdapter(null);

                    String[] thumbColumns = { MediaStore.Images.Thumbnails.DATA,
                            MediaStore.Images.Thumbnails.IMAGE_ID };

                        String[] mediaColumns = { MediaStore.Images.Media._ID,
                            MediaStore.Images.Media.DATA, MediaStore.Images.Media.TITLE,
                            MediaStore.Images.Media.MIME_TYPE };

                        cursor = managedQuery(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                            mediaColumns, null, null, null);

                        ArrayList<ImageViewInfo> videoRows = new ArrayList<ImageViewInfo>();

                        if (cursor.moveToFirst()) {
                          do {

                            ImageViewInfo newVVI = new ImageViewInfo();
                            int id = cursor.getInt(cursor.getColumnIndex(MediaStore.Images.Media._ID));
                            Cursor thumbCursor = managedQuery(
                                MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI,
                                thumbColumns, MediaStore.Images.Thumbnails.IMAGE_ID
                                    + "=" + id, null, null);
                            if (thumbCursor.moveToFirst()) {
                              newVVI.thumbPath = thumbCursor.getString(thumbCursor
                                  .getColumnIndex(MediaStore.Images.Thumbnails.DATA));
                              Log.v("", newVVI.thumbPath);
                            }

                            newVVI.filePath = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA));
                            newVVI.title = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.TITLE));
                            Log.v("", newVVI.title);
                            newVVI.mimeType = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.MIME_TYPE));
                            Log.v("", newVVI.mimeType);
                            videoRows.add(newVVI);
                          } while (cursor.moveToNext());
                        }

                        mGridView.invalidateViews();
                        mGridView.setAdapter(new ImageAdapter(ImageGridActivity.this,videoRows));


                }
                else if (items[item].equals("Properties"))
                {
                    if (cursor.moveToPosition(position)) {
                          int fileColumn = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                          //int fileSize = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.SIZE);
                          String filePath = cursor.getString(fileColumn);
                          //String fileSizes = cursor.getString(fileSize);
                        File newFile = new File(filePath);
                        AlertDialog.Builder builder = new AlertDialog.Builder(ImageGridActivity.this);
                        builder.setTitle("File Details :");
                        builder.setMessage("Name: "+newFile.getName());
                        builder.setMessage("Path: "+filePath);
                        //builder.setMessage("Size: "+fileSizes);
                        builder.setCancelable(true);
                        AlertDialog alert = builder.create();
                        alert.show();

                        }                                           
                }               
            }
        });
        AlertDialog alert = builder.create();
        alert.show();

    }
});


}


class ImageViewInfo {
  String filePath;
  String mimeType;
  String thumbPath;
  String title;
}
public class ImageAdapter extends BaseAdapter {
  private Context context;
  private List<ImageViewInfo> videoItems;

  LayoutInflater inflater;

  public ImageAdapter(Context _context,
      ArrayList<ImageViewInfo> _items) {
    context = _context;
    videoItems = _items;

    inflater = (LayoutInflater) context
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
  }

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

  public Object getItem(int position) {
    return videoItems.get(position);
  }

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

    // 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(getBaseContext());
            imageView.setLayoutParams(new GridView.LayoutParams(95, 95));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
        } else {
            imageView = (ImageView) convertView;
        }
        */

        //View videoRow = inflater.inflate(R.layout.row, null);
        final ImageView videoThumb = (ImageView) getLayoutInflater().inflate(R.layout.rows, parent, false);
        if (videoItems.get(position).thumbPath != null) {
          videoThumb.setImageURI(Uri
              .parse(videoItems.get(position).thumbPath));
        }
        else
        {
            videoThumb.setImageResource(R.drawable.ic_empty);
        }



        /*
            final ImageView imageView;
            if (convertView == null) {
                imageView = (ImageView) getLayoutInflater().inflate(R.layout.row, parent, false);
            } else {
                imageView = (ImageView) convertView;
            }

            imageView.setImageURI(Uri.parse(videoItems.get(position).thumbPath));

        //Log.v("", "file://"+videoItems.get(position).thumbPath);
        //imageView.setImageURI(Uri.parse("file://"+videoItems.get(position).filePath));
        */
        return videoThumb;
    }
}

Answer 1

您需要从适配器中的imageList中删除该文件。这样，文件路径就会从列表中删除，它只显示列表中的图像。

public class ImageAdapter extends BaseAdapter {
    private Context mContext;
    ArrayList<String> itemList = new ArrayList<String>();

    public ImageAdapter(Context c) {
        mContext = c;   
    }

    void add(String path){
        itemList.add(path); 
    }

    void remove(String path){
        itemList.remove(path);
    }
}

public void function_delete(int id){  
    File file = new File(path);
    if(file.exists())
    {
        boolean deleted = file.delete();
    }
    myImageAdapter.remove(path);
    myImageAdapter.notifyDataSetChanged();

    Toast.makeText(this, "Deleted", Toast.LENGTH_SHORT).show();  
}