code: private void showChangeTagDialog() {
      View view = getLayoutInflater().inflate(R.layout.dialog_change_tag, null, false);
      final EditText tagEditText = (EditText) view.findViewById(R.id.tag);
      tagEditText.setText(tagView.getText());
  
      new AlertDialog.Builder(this)
          .setTitle(R.string.change_tag)
          .setView(view)
          .setNegativeButton(android.R.string.cancel, null)
          .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
              String tag = tagEditText.getText().toString().trim();
              if (!tag.isEmpty()) {
                tagView.setText(tag);
              }
            }
          })
          .show();
    }
docs: Show a dialog for user to change the tag, empty text is not allowed.