MultiplePermissionAtATime.java

  public boolean hasPermission(String permission) {
        return  ContextCompat.checkSelfPermission(getApplicationContext(), permission) == PackageManager.PERMISSION_GRANTED;
    }

  public void askForMultiplePermissions(){
        final int REQUEST_CODE = 13;
        String cameraPermissin = Manifest.permission.CAMERA;
        String readContactsPermission = Manifest.permission.READ_CONTACTS;
        String readExternalStoragePermission = Manifest.permission.READ_EXTERNAL_STORAGE;

        List<String> permissionList = new ArrayList<>();

        if (!hasPermission(cameraPermissin)){
            permissionList.add(cameraPermissin);
        }
        if (!hasPermission(readContactsPermission)){
            permissionList.add(readContactsPermission);
        }
        if (!hasPermission(readExternalStoragePermission)){
            permissionList.add(readExternalStoragePermission);
        }
        if (!permissionList.isEmpty()){
            String[] permissions = permissionList.toArray(new String[PERMISSIONS.size()]);
            ActivityCompat.requestPermissions(this,permissions,REQUEST_CODE);
        }
    }