This are some methods I usually use to handle android 6 permissions

AndroidMarshmallowPermissions.java

/**
     * Check whether the passed permissions are granted and if not it requests them.
     * @param activity The activity that requires the permissions
     * @param requestCode The request code
     * @param permissions The permissions you want to grant
     */
    public static void requestPermissionsNotAllowed(@NonNull  Activity activity, 
                                                    @NonNull int requestCode, 
                                                    @NonNull String... permissions){
        ArrayList<String> missing = new ArrayList<>(permissions.length);
        for(String perm : permissions){
            int resp = ContextCompat.checkSelfPermission(activity,perm);
            if(resp != PackageManager.PERMISSION_GRANTED){
                missing.add(perm);
            }
        }
        ActivityCompat.requestPermissions(activity,
                missing.toArray(new String[missing.size()]),
                requestCode);
    }

    /**
     * Returns True if the permission is granted false otherwise
     * @param context  The context from where its being asked
     * @param permission  The permission to be asked @see android.Manifest.permission
     * @return true if granted, else false
     */
    public static boolean isPermissionGranted(@NonNull Context context, @NonNull String permission){
        return ContextCompat.checkSelfPermission(context, permission) == PackageManager.PERMISSION_GRANTED; 
    }