try{
   String fileName = "myTextFile.txt";
   FileWriter fw = new FileWriter(fileName, true);
   fw.write(" some text & _");
   fw.close();
}catch(FileNotFoundException fnfe){
   System.err.println("FileNotFoundException: " + fnfe.getMessage());
}catch(IOException  ioe){
   System.err.println("IOException: " + ioe.getMessage());
 
}