Question about writing a text file

Question

As we know, we can write a text file using class "FileWriter". I did a test (Please see the code below).
I found that if I used Notepad to open it, it would show "ab", But if I used "MS Word" or "UltraEdit" to open it, it would show " 'a' , new line and 'b' ".
Why Notepad can not display the right format? What's wrong with my code?
//code begin*************************************************
import java.io.*;
public class writeTest {
public writeTest() {
     try{
          File f = new File( "C:\\writeTest.txt" );
          FileWriter fout = new FileWriter( f );
          fout.write( "a" );
          fout.write( "\n" );
          fout.write( "b" );
          fout.close();
     catch( IOException e ){
          e.printStackTrace();
public static void main(String[] args) {
writeTest writeTest1 = new writeTest();
//code end***************************************************

Answer 1

You may use system-dependent line separator:
static final String ls=System.getProperty("line.separator");
fout.write( "a" );
fout.write( ls );
fout.write( "b" );