1. Click a button to take a photo.
2. Save photo.
3. Add photo into the gallery.
4. Show photo into an ImageView.

photoFile = createImageFile();

private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = timeStamp;
    File imageFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), imageFileName + ".jpg");

    if (imageFile.exists()){
        imageFile.delete();
        imageFile.createNewFile();
    }
    else{
        imageFile.createNewFile();
    }

    mCurrentPhotoPath = imageFile.getAbsolutePath();

    return imageFile;
}

if (photoFile != null) {
    Uri photoURI = FileProvider.getUriForFile(getContext(),
                     "es.antonio.prueba.fileprovider",
                     photoFile);
     takePhotoIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
    startActivityForResult(takePhotoIntent, REQUEST_CAMERA);
 }

private void galleryAddPic() {
    Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
    File f = new File(mCurrentPhotoPath);
    Uri contentUri = Uri.fromFile(f);
    mediaScanIntent.setData(contentUri);
    getContext().sendBroadcast(mediaScanIntent);
}

private void setPic(ImageView mImageView) {
    BitmapFactory.Options bmOptions = new BitmapFactory.Options();

    // Decode the image file into a Bitmap sized to fill the View
    bmOptions.inJustDecodeBounds = false;
    bmOptions.inPurgeable = true;

    Bitmap bitmap = BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
    mImageView.setImageBitmap(bitmap);
}