How to delete file from removable sd card (second external storage)?

Question

I am trying to delete a file (PATH_TO_SD_CARD/DCIM/1.PDF) on android 9 from my sd card (removable).

1. I get the volumePaths where the 2nd one is my sd card.

private static String[] getVolumePaths(Context context) {
    String[] volumes = null;
    StorageManager managerStorage = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);
    if (managerStorage == null) {
        return volumes;
    }
    try {
        return (String[]) managerStorage.getClass().getMethod("getVolumePaths", new Class[0]).invoke(managerStorage, new Object[0]);
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
        return volumes;
    } catch (IllegalArgumentException e2) {
        e2.printStackTrace();
        return volumes;
    } catch (IllegalAccessException e3) {
        e3.printStackTrace();
        return volumes;
    } catch (InvocationTargetException e4) {
        e4.printStackTrace();
        return volumes;
    }
}

    String[] volumePaths = getVolumePaths(getContext());
    Log.v("VOLUME1: ", "-> "+volumePaths[0]);
    Log.v("VOLUME2: ", "-> "+volumePaths[1]);

LocCat:

2019-07-19 17:06:15.577 13257-13257/com.spicysoftware.spicypdfreader V/VOLUME2:: -> /storage/2585-1513

2. I check if the file exists which returns true

Log.v("FILE EXISTS?", "-> "+new File("/storage/2585-1513/DCIM/1.PDF").exists());

LogCat

2019-07-19 17:06:16.577 13257-13257/com.spicysoftware.spicypdfreader V/FILE EXISTS? -> true

3.1 I am trying to delete the file

But this way does not work, why?

new File("/storage/2585-1513/DCIM/1.PDF").delete();

3.2 I am trying to delete the file via DOCUMENT_FILE_TREE

// call for document tree dialog
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
startActivityForResult(intent, 123);

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
        case 123:
            if (resultCode == Activity.RESULT_OK) {
                String strFilePath = data.getData().getPath()+"/DCIM/1.PDF";
                try {
                    if(new File(strFilePath).delete()){
                        Log.v("FILE", "DELETED");
                    }else{
                        Log.v("FILE", "NOT DELETED");
                    }
                }catch (Exception e){
                    Log.v("ERROR: ", "-> "+e);
                }
            }
            break;
    }
}

LogCat

2019-07-19 17:23:20.523 14343-14343/com.spicysoftware.spicypdfreader V/FILE: NOT DELETED

So my question is: How to delete file from removable sd card (second external storage)? This is so weird... I was 2 days on this problem and didn't find any solution how to delete a file on this sd card...

I also used the storage access framework which did not work. If it is the only way to handle that pls add an example.

Answer 1

How to delete file from removable sd card (second external storage)?

You don't. You do not have read/write access to arbitrary locations on removable storage.

I also used the storage access framework which did not work

Not really. You used ACTION_OPEN_DOCUMENT_TREE to get a Uri, then tried to turn it into a File. That will not work, as a Uri is not a file.

The simplest solution is:

• Use ACTION_OPEN_DOCUMENT

• Pass the Uri that you get (data.getData() from your question) and pass that to DocumentFile.fromSingleUri()

• Call delete() on that DocumentFile

Answer 2

By security, you can access to your SD Card but you can only write & read files into the directory that was created for your app or files inside the directories created by your app (using WRITE_EXTERNAL_STORAGE permission).

for example if your external storage path is

/storage/13257-13257/

and your app package name is com.spicysoftware.spicypdfreader

You can access and delete files created inside this path:

 /storage/13257-13257/com.spicysoftware.spicypdfreader

By the way i suggest to you use ContextCompat.getExternalFilesDirs(context, null) to get the path of your /files directory /storage/13257-13257/com.spicysoftware.spicypdfreader/files .

Example:

 File[] storages = ContextCompat.getExternalFilesDirs(context, null);
Log.i(TAG, "storage[0]: " + storages[0]);
Log.i(TAG, "storage[1]: " + storages[1]);

---

in conclusion, you can delete files here:

new File("/storage/13257-13257/com.spicysoftware.spicypdfreader/files/1.PDF").delete();

or here (outside /files directory):

new File("/storage/13257-13257/com.spicysoftware.spicypdfreader/1.PDF").delete();

but is not possible to do this:

new File("/storage/13257-13257/DCIM/1.PDF").delete();