WRITE_SETTINGS Permission ambiguity

Question

I'm building my app for android 6.0 Marshmallow, it needs WRITE_SETTTINGS permission. After searching from here I came to know that calling this:

requestPermissions(new String[]{Manifest.permission.WRITE_SETTINGS},
              101);

won't show dialog permission. So, based on CommonsWare solution, we should check if Settings.System.canWrite() returns true or false. So, I should call Activity with ACTION_MANAGE_WRITE_SETTINGS as action.

But the issue is when I call this activity, it shows my app has already been granted permission though the method Settings.System.canWrite() returns false.

Am I missing something here or I have to disable it then enable it again.

Answer 1

On my Nexus 6 using Android 6.0.1 (MMB29S) this code:

if (!Settings.System.canWrite(this)) {
    Intent intent = new Intent(Settings.ACTION_MANAGE_WRITE_SETTINGS);
    intent.setData(Uri.parse("package:dummy"));
    startActivity(intent);
}

opens the Settings only if Allow modify system settings is set to disabled. For instance, at first launch after fresh install (i.e. not reinstall)

Edit (see comments): Some device may be bugged with respect to this code, in those canWrite() always returns false, whatever the value of the setting.

Answer 2

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (Settings.System.canWrite(context)) {

            //Write code to feature for eg. set brightness or vibrate device 
           /* ContentResolver cResolver = context.getContentResolver();
            Settings.System.putInt(cResolver, Settings.System.SCREEN_BRIGHTNESS,brightness);*/
        }
        else {
            showBrightnessPermissionDialog(context);
        }

Dialog :-

 private  static  void showBrightnessPermissionDialog(final Context context) {

    final AlertDialog.Builder builder = new AlertDialog.Builder(context);
    builder.setCancelable(true);
    final AlertDialog alert = builder.create();
    builder.setMessage("Please give the permission to change brightness. \n Thanks ")
            .setCancelable(false)
            .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    Intent intent = new Intent(android.provider.Settings.ACTION_MANAGE_WRITE_SETTINGS);
                    intent.setData(Uri.parse("package:" + context.getPackageName()));
                   // intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                    context.startActivity(intent);
                    alert.dismiss();
                }
            });
    alert.show();
}

for eg. complete code for Brightness .

 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Build;
 import android.provider.Settings;
 import android.support.v7.app.AlertDialog;

  public class BrightnessHelper {

  public static void  setBrightness(Context context, int brightness){

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (Settings.System.canWrite(context)) {

      //Write code to feature for eg. set brightness or vibrate device
            ContentResolver cResolver = context.getContentResolver();  Settings.System.putInt(cResolver,  Settings.System.SCREEN_BRIGHTNESS,brightness);
        }
        else {
            showBrightnessPermissionDialog(context);
        }
    }

}

public static int getBrightness(Context context) {
    ContentResolver cResolver = context.getContentResolver();
    try {
        return Settings.System.getInt(cResolver,  Settings.System.SCREEN_BRIGHTNESS);
    } catch (Settings.SettingNotFoundException e) {
        return 0;
    }
}

private  static  void showBrightnessPermissionDialog(final Context context) {

    final AlertDialog.Builder builder = new AlertDialog.Builder(context);
    builder.setCancelable(true);
    final AlertDialog alert = builder.create();
    builder.setMessage("Please give the permission to change brightness. \n Thanks ")
            .setCancelable(false)
            .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    Intent intent = new Intent(android.provider.Settings.ACTION_MANAGE_WRITE_SETTINGS);
                    intent.setData(Uri.parse("package:" + context.getPackageName()));
                   // intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                    context.startActivity(intent);
                    alert.dismiss();
                }
            });
    alert.show();
}


/*
    private boolean checkSystemWritePermission(Activity activity) {
        boolean retVal = true;
        if (Build.VERSION.SDK_INT >= activity.Build.VERSION_CODES.M) {
            retVal = Settings.System.canWrite(activity.getApplicationContext());
           // Log.d(TAG, "Can Write Settings: " + retVal);
            if(retVal){
                Toast.makeText(activity, "Write allowed :-)", Toast.LENGTH_LONG).show();
            }else{
                Toast.makeText(this, "Write not allowed :-(", Toast.LENGTH_LONG).show();
                FragmentManager fm = getFragmentManager();
                PopupWritePermission dialogFragment = new PopupWritePermission();
                dialogFragment.show(fm, getString(R.string.popup_writesettings_title));
            }
        }
        return retVal;
    }*/
}

Answer 3

write this method as follows:

public void writePermission() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (!Settings.System.canWrite(getApplicationContext())) {
                Intent intent = new Intent(Settings.ACTION_MANAGE_WRITE_SETTINGS, Uri.parse("package:" + getPackageName()));
                startActivityForResult(intent, 200);

        }
    }
}

then call the method (writePermission) just before you call your dialog

I hope this helps

Answer 4

It turns out that if you have CHANGE_NETWORK_STATE declared in your manifest, the toggle to allow WRITE_SETTINGS will default to the on position even though the permission is not granted. You don't even need to declare WRITE_SETTINGS to encounter this bug.