Accessing getExternalStorageDirectory

Question

Using some pretty simple android code I am trying to access a folder according to the following logic:

public void try_to_navigate_local_dir(){
    Environment e = new Environment();
    ArrayList<String> filesList = new ArrayList<String>();
    String sd_card = Environment.getExternalStorageDirectory().toString() + "/subdir_x";
    File file = new File( sd_card ) ;
    File list[] = file.listFiles();
    for( int i=0; i< list.length; i++) {
        filesList.add( list[i].getName() );
    }
}

Where subdir_x is created by another application on my phone.

I can view in those folders using file manager, yet my code returns null when I try to file.listFiles().

How may I access these files?

http://stackoverflow.com/a/41221852/5488468 – Bipin Bharti Dec 20 '16 at 10:45 — Bipin Bharti, Dec 20 '16 at 10:45

score 10 · Accepted Answer · edited Nov 07 '17 at 16:02

I have tried this logic in Marshmallow (6.0) :

make sure you have this in your manifest :

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

when try to access external storage please check the permission before entering the logic to read directory :

public void checkPermissionReadStorage(Activity activity){
         if (ContextCompat.checkSelfPermission(activity,      Manifest.permission.READ_EXTERNAL_STORAGE) !=     PackageManager.PERMISSION_GRANTED) {

        // Should we show an explanation?
        if (ActivityCompat.shouldShowRequestPermissionRationale(activity,
                Manifest.permission.READ_EXTERNAL_STORAGE)) {

            // Show an expanation to the user *asynchronously* -- don't block
            // this thread waiting for the user's response! After the user
            // sees the explanation, try again to request the permission.

        } else {

            // No explanation needed, we can request the permission.

            ActivityCompat.requestPermissions(activity,
                    new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
                    MY_PERMISSIONS_REQUEST_READ_STORAGE);

            // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
            // app-defined int constant. The callback method gets the
            // result of the request.
        }
    }
}

and then override this method in your activity :

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case PermissionManager.MY_PERMISSIONS_REQUEST_READ_STORAGE: {
            //premission to read storage
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                // permission was granted, yay! Do the
                // contacts-related task you need to do.

            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
                Toast.makeText(SnapSellAddActivity.this, "We Need permission Storage", Toast.LENGTH_SHORT).show();
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
}

after that you can finally read the external storage in android devices, I tried like this method to read directory in external storage :

public File getPreviewTempExternalDirectory(Context context) {
    File previewDir = new File(context.getExternalFilesDir(null), PLACE YOUT DIR HERE);
    if (!previewDir.exists()) previewDir.mkdir();
    return previewDir;
}

and now you have the directory, you can list file or create file there. hope it helps.

score 3 · Answer 2 · edited May 23 '17 at 11:46

Prior to Marshmallow, follow @Cory Charlton's answer. However his answer for Android Marshmallow (6.0) won't work.

Actually as of Android 6.0 (API level 23), we don't have the following permission anymore.

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

For more information, please this question:

Android Marshmallow permission model on OS 4.0 READ_EXTERNAL_STORAGE permission always not granted

By the way, Environment e = new Environment(); is useless, remove it.

score 0 · Answer 3 · answered Jan 18 '16 at 22:39

Make sure your AndroidManifest.xml has the appropriate permission:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

The next problem might be your filename. I use the following in one of my applications and it works (note the trailing slash and lack of leading slash):

directory = new File(Environment.getExternalStorageDirectory(), "Subdirectory/")
final File[] files = directory.listFiles();

The next problem might be the path Environment.getExternalStorageDirectory() is giving you. Newer devices have a partition on the internal storage that emulates an sd card and Environment.getExternalStorageDirectory() can return this rather than the real sd card.

Accessing getExternalStorageDirectory

3 Answers3

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