我正在使用光标浏览我的内部文件夹，但文件夹是空的？

Question

我正在尝试查找内部存储中包含图像的所有文件夹。为此，我正在使用光标。光标不是空的，它是空的，我应该寻找不同的空间来找到这些文件夹吗？

        imageFolders = new ArrayList<String>();

        String[] projection = new String[]{
                MediaStore.Images.Media.DATA,
                MediaStore.Images.Media._ID,
                MediaStore.Images.Media.BUCKET_DISPLAY_NAME,
                MediaStore.Images.Media.DATE_TAKEN};
        System.out.println("Print progress: Created String Projection");
        System.out.println("Print progress: " + projection[0] + " " + projection[1] + " " + projection[2] + " " + projection[3]);

        Uri imageUri = MediaStore.Images.Media.INTERNAL_CONTENT_URI ;
        System.out.println("Print progress: images uri " + imageUri);
        final String orderBy = android.provider.MediaStore.Images.Media.DATE_TAKEN;
        System.out.println("Print progress: orderBy " + orderBy);

        Cursor cur = getContentResolver().query(imageUri, projection, // Which columns to return
                null, // Which rows to return (all rows)
                null, // Selection arguments (none)
                orderBy + " DESC" // Ordering
        );
        System.out.println("Print progress: cursor created");
        ArrayList<String> imagePath;



        if (cur.moveToFirst()) {
            System.out.println("Print progress: entered cursor"
            );
            String bucket, date;

            int bucketColumn = cur.getColumnIndex(MediaStore.Images.Media.BUCKET_DISPLAY_NAME);
            System.out.println("Print progress: bucketColumn: " + bucketColumn);
            int dateColumn = cur.getColumnIndex(MediaStore.Images.Media.DATE_TAKEN);
            System.out.println("Print progress: dateColumn: " + dateColumn);
            do {
                bucket = cur.getString(bucketColumn);
                System.out.println("Print progress: bucket: " + bucket);

                date = cur.getString(dateColumn);
                System.out.println("Print progress: date: " + date);
                if (!imageFolders.contains(bucket)) {
                    imageFolders.add(bucket);
                }
                imagePath = listImageByFolder.get(bucket);
                if (imagePath == null) {
                    imagePath = new ArrayList<String>();
                }
                imagePath.add(cur.getString(cur
                        .getColumnIndex(MediaStore.Images.Media.DATA)));
                listImageByFolder.put(bucket, imagePath);
            } while (cur.moveToNext());
        }
        System.out.println("Print progress: Found the Internal Image Folders");
        return imageFolders;

Answer 1

假设 refuses to moveToFirst 你的意思是if 块被跳过，因为moveToFirst() 返回false。当Cursor 为空时会发生这种情况：

public abstract boolean moveToFirst()

将光标移动到第一行。如果 光标为空。 - 安卓API.