Helper class that allows you to easily change the ringtone on a device for all versions of Android

RingtoneUtils.java

import android.content.ContentUris;
import android.content.Context;
import android.content.Intent;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Build;
import android.provider.MediaStore;
import android.provider.Settings;
import android.support.annotation.NonNull;
import android.support.annotation.RequiresApi;
import android.util.Log;
import android.widget.Toast;

public class RingtoneUtils {

    private static final String LOG_TAG = "RingtoneUtils";

    public static boolean setRingtone(@NonNull Context context, @NonNull Uri ringtoneUri) {
        Log.v(LOG_TAG, "Setting Ringtone to: " + ringtoneUri);

        if (!hasMarshmallow()) {
            Log.v(LOG_TAG, "On a Lollipop or below device, so go ahead and change device ringtone");
            setActualRingtone(context, ringtoneUri);
            return true;
        }
        else if(hasMarshmallow() && canEditSystemSettings(context)) {
            Log.v(LOG_TAG, "On a marshmallow or above device but app has the permission to edit system settings");
            setActualRingtone(context, ringtoneUri);
            return true;
        }
        else if(hasMarshmallow() && !canEditSystemSettings(context)) {
            Log.d(LOG_TAG, "On android Marshmallow and above but app does not have permission to" +
                    " edit system settings. Opening the manage write settings activity...");
            startManageWriteSettingsActivity(context);
            Toast.makeText(context, "Please allow app to edit settings so your ringtone can be updated", Toast.LENGTH_LONG).show();
            return false;
        }

        return false;
    }

    private static void setActualRingtone(@NonNull Context context, @NonNull Uri ringtoneUri) {
        RingtoneManager.setActualDefaultRingtoneUri(context, RingtoneManager.TYPE_RINGTONE, ringtoneUri);
    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    private static void startManageWriteSettingsActivity(@NonNull Context context) {
        Intent intent = new Intent(Settings.ACTION_MANAGE_WRITE_SETTINGS);
        // Passing in the app package here allows the settings app to open the exact app
        intent.setData(Uri.parse("package:" + context.getApplicationContext().getPackageName()));
        // Optional. If you pass in a service context without setting this flag, you will get an exception
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent);
    }

    private static boolean hasMarshmallow() {
        // returns true if the device is Android Marshmallow or above, false otherwise
        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M;
    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    private static boolean canEditSystemSettings(@NonNull Context context) {
        // returns true if the app can edit system settings, false otherwise
        return Settings.System.canWrite(context.getApplicationContext());
    }

}

Example usage:

import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.annotation.NonNull;

    public class ExampleUsage {

        public void setFirstSongOnDeviceAsRingtone(@NonNull Context context) {
            Uri mediaContentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
            String[] projection = new String[] { MediaStore.Audio.Media._ID, MediaStore.Audio.Media.DATA};

            Cursor mediaCursor = context.getContentResolver().query(mediaContentUri, projection, null, null, null);

            if(mediaCursor != null) {
                if(mediaCursor.getCount() >= 0) {
                    // Move to first song item
                    mediaCursor.moveToPosition(0);
                    long songId = mediaCursor.getLong(mediaCursor.getColumnIndex(MediaStore.Audio.Media._ID));
                    String songUri = mediaCursor.getString(mediaCursor.getColumnIndex(MediaStore.Audio.Media.DATA));
                    Uri songContentUri = MediaStore.Audio.Media.getContentUriForPath(songUri);
                    Uri ringtoneUri = ContentUris.withAppendedId(songContentUri, songId);

                    // Use class to change Ringtone
                    RingtoneUtils.setRingtone(context, ringtoneUri);
                }

                mediaCursor.close();
            }
        }

    }