Oreo (WRITE EXTERNAL STORAGE) Permission

Question

According to "developer.android.com"

If the app targets Android 8.0 (API level 26), the system grants only  READ_EXTERNAL_STORAGE at that time; however, if the app later requests  WRITE_EXTERNAL_STORAGE, the system immediately grants that privilege  without prompting the user. 

Now, I have the READ_EXTERNAL_STORAGE and I'm requesting the DownloadManager to download a file in the Public Download folder

downloadRequest.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, mAttachmentItem.getFilename()); 

Unfortunately, I got

E/UncaughtException: java.lang.IllegalStateException: Unable to create directory: /storage/emulated/0/data/user/0/com.abc.cba/files                                                                            at android.app.DownloadManager$Request.setDestinationInExternalPublicDir(DownloadManager.java:699) 

I have declared both of permissions in the Manifest

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

Read permission is already Granted and in Runtime I'm requesting Write permission, the system doesn't prompt any message or dialog, it's always Denied(Not Granted) in "onRequestPermissionsResult"

public static boolean isPermissionsToAccessStorageAreGranted(Context context, Activity activity) {     ArrayList<String> permissions = new ArrayList<>();      if (!PermissionUtil.checkPermissions(context, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {         permissions.add(Manifest.permission.WRITE_EXTERNAL_STORAGE);     }      if (!permissions.isEmpty()) {         String[] permissionsList = permissions.toArray(new String[permissions.size()]);         PermissionUtil.requestPermissions(activity, permissionsList,                 PermissionUtil.REQUESTCODE_ACCESS_STORAGE);         return false;     } else {         return true;     } }   @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {     super.onRequestPermissionsResult(requestCode, permissions, grantResults);     if(requestCode==REQUESTCODE_ACCESS_STORAGE && grantResults[0]== PackageManager.PERMISSION_GRANTED){  /* downloadFile(); */            } } 

I'm trying to grant those two permissions via ADB, it shows me an error:

adb shell pm grant com.abc.cba  android.permission.WRITE_EXTERNAL_STORAGE Operation not allowed: java.lang.SecurityException: Package com.abc.cbs  has not requested permission android.permission.WRITE_EXTERNAL_STORAGE  adb shell pm grant com.abc.cba  android.permission.READ_EXTERNAL_STORAGE Operation not allowed: java.lang.SecurityException: Can't change  android.permission.READ_EXTERNAL_STORAGE. It is required by the  application 

Answer 1

Actually, It was an external problem. One of App Libs I'm using request the WRITE_EXTERNAL_PERMISSION with android:maxSdkVersion. So when merging with my Manifest it will remove the permission for the whole application.

The Solution is to add:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" tools:node="replace"/>  

Answer 2

You are correct in adding the permissions to the manifest:

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

For versions of Lollipop and higher, you need to also request the permissions at runtime. To solve this problem, I created a new method requestAppPermission that I call when the main activity is created. This method runs only for Lollipop and higher, and returns early otherwise:

private void requestAppPermissions() {     if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {         return;     }      if (hasReadPermissions() && hasWritePermissions()) {         return;     }      ActivityCompat.requestPermissions(this,             new String[] {                     Manifest.permission.READ_EXTERNAL_STORAGE,                     Manifest.permission.WRITE_EXTERNAL_STORAGE             }, REQUEST_WRITE_STORAGE_REQUEST_CODE); // your request code }  private boolean hasReadPermissions() {     return (ContextCompat.checkSelfPermission(getBaseContext(), Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED); }  private boolean hasWritePermissions() {     return (ContextCompat.checkSelfPermission(getBaseContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED); } 

I call this method in the activity's onCreate:

@Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     // Other things     requestAppPermissions(); } 

On first load, this will prompt the user to accept permissions.

Then, before you run any code that needs to read and write to storage, you can check these permissions, either by storing the values or running those checks again using methods hasReadPermissions() and hasWritePermissions() defined above.