stop files from truncating Java?

here is my code

try {
        fstream = new FileWriter("/Applications/AirDrop/contacts.txt");
        BufferedWriter out = n开发者_开发问答ew BufferedWriter(fstream);

          out.write(stringToInsert);

        out.close();

    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

now everytime I try to call this method (this is code is in a method called writeToFile with a string parameter) the string which

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You need to use the two-argument constructor of FileWriter:

fstream = new FileWriter("/Applications/AirDrop/contacts.txt", true);

Better yet: don't use FileWriter at all, because it always uses the platform default encoding, which is not usually a good idea! Instead you should explicitly specify which encoding to use (UTF-8 is usually a good default, if you don't know what else to chose):

fstream = new OutputStreamWriter(new FileOutputStream("/Applications/AirDrop/contacts.txt", true), "UTF-8");

Another hint: it is pretty likely that constantly opening and closing the file is not the best idea: You should usually open the file once for writing, write everything you need to write to it and then close it.