Use store() to save the properties : Properties « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. Properties

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Properties;

public class MainClass {
  public static void main(String args[]) throws Exception {
    Properties p = new Properties();
    p.load(new FileInputStream("test.txt"));

    p.store(new FileOutputStream("t.txt"),"no comments");
  }
}

//File: test.txt
/*
foo:bar
one
two
three=four
five  six seven eight
nine ten
*/

foo=bar
one=
two=
three=four
five=six seven eight
nine=ten