Using DataOutputStream in Java gives some Chinese output

I was using DataOutputStream in Java today, but it gave me a Chinese output, that was absolutely NOT what I had expected... Can someone please spot the error in the code?

private void generateButtonActionPerformed(java.awt.event.ActionEvent evt) {
    textToSet="       Student Information";
    textToSet=textToSet+"\nName\t: "+TitleBox.getSelectedItem()+" "+FirstNameField.getText()+" "+LastNameField.getText();
    textToSet=textToSet+"\nClass\t: "+ClassField.getText();
    TextArea.setText(textToSet);
}

private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
    try{
        File f=new File("C:\\Users\\username\\Desktop\\ID Card.txt");
        DataOutputStream fs=new DataOutputStream(new BufferedOutputStream(new FileOutputStream(f)));
        fs.writeUTF(textToSet);
        Desktop d=Desktop.getDesktop();
        d.open(f);
        fs.close();
    }
    catch(Exception e){
        e.printStackTrace();
    }
}

TitleBox is a JComboBox, FirstNameField, LastNameField, and ClassField are JTextField's. TextArea is a JTextArea.

When I choose "Mr." in TitleBox, type "Man" in FirstNameField, "Ly" in LastNameField and "7th" in ClassField, I get the output:

       Student Information
Name    : Mr. Man Ly
Class   : 7th

in the TextArea, but in the file, IDCard.txt, I get the output:

㠀†††匠畴敤瑮䤠普牯慭楴湯上浡॥›牍‮慍祌䌊慬獳㨉㜠桴

textToSet is a String variable defined in the public scope... Can someone point me in the right direction? Is there something wrong with the writeUTF() code?