File fileDir = new File("PATH");
BufferedReader in = new BufferedReader(new FileReader(fileDir));
			
String str = "";
styledText.setText(""); 
			
while ((str = in.readLine()) != null) {
        //Just to see if was right
        System.out.println(str);

        //to write each line of the file in the styledText
	styledText.setText(styledText.getText() + "\n" + str);
}
			
in.close();