如何在活动中使返回的字符串公开

Question

我有一个活动进入我的服务器并获取一个带有字符串的.txt文件。我想从另一个活动中调用.txt文件中的字符串，以用作函数中的变量。我怎样才能公开这个？我如何从其他活动中调用它？ 代码：

public class getter extends AppCompatActivity {

String TextFileURL = "http://1.2.3.4/test.txt" ;
TextView textView ;
Button button ;
URL url ;
String TextHolder = "" , TextHolder2 = "";
BufferedReader bufferReader ;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_get);

    textView = (TextView)findViewById(R.id.textView);

    button = (Button)findViewById(R.id.button);

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            new GetNotePadFileFromServer().execute();

        }
    });

}

public class GetNotePadFileFromServer extends AsyncTask<Void, Void, Void>{

    @Override
    protected Void doInBackground(Void... params) {

        try {
            url = new URL(TextFileURL);

            bufferReader = new BufferedReader(new InputStreamReader(url.openStream()));

            while ((TextHolder2 = bufferReader.readLine()) != null) {

                TextHolder += TextHolder2;
            }
            bufferReader.close();

        } catch (MalformedURLException malformedURLException) {

            // TODO Auto-generated catch block
            malformedURLException.printStackTrace();
            TextHolder = malformedURLException.toString();

        } catch (IOException iOException) {

            // TODO Auto-generated catch block
            iOException.printStackTrace();

            TextHolder = iOException.toString();
        }

        return null;

    }


    @Override
    protected void onPostExecute(Void finalTextHolder) {

        textView.setText(TextHolder);

        super.onPostExecute(finalTextHolder);
    }

}

我试图用这个来调用字符串：

    public static int getinstVersionCode(Context mContext) {
    if (mContext != null) {
        try {
            return mContext.getPackageManager().getPackageInfo(getter.GetNotePadFileFromServer., 0).versionCode;
        } catch (PackageManager.NameNotFoundException ignored) {
        }
    }
    return 0;
}