Saving input to a file is replaced when re-running

Question

I'm trying to create something similar to a mail server. Now, I'm supposed to have a file called 'Credentials' that saves the email and password entered each time I run the client.

File Credentials = new File("Server\\Credentials.txt");
 try{
       if(Credentials.createNewFile()){
               System.out.println("Credentials created");
         }else {System.out.println("Credentials already exists");}

  }catch(Exception error){}

try (
      PrintWriter out = new PrintWriter(Credentials, "UTF-8")
    ) {
               out.println("Email: " + email);
               out.println("Password: " + password);
      } catch(IOException e) {
               e.printStackTrace();
      }

However, each time a client runs, it replaces the old email and password. Any idea how to make it continue to the next line without replacing? Thank you.

Fair, retracted the vote. You have to open your PrintWriter in append mode instead. Check the javadoc for its constructors, there should be one taking a `boolean` to indicate append instead o truncate mode. — Zabuzard, Jan 26 '21 at 17:46
That said, the way you are interacting with your file is very old. Look into NIO, the new modern interface is much simpler and clearer to use. — Zabuzard, Jan 26 '21 at 17:46
@Abra True, but NIO only really got very interesting starting with Java 7, especially 8 and also 9, due to `readAllLines`, `lines`, `readString`, `write`, `writeString` which covers almost all basic file interactons. Although thats also some years ago already, given that we are on 15 already :D — Zabuzard, Jan 26 '21 at 17:59
@Zabuzard Ah, sorry lol. Our professor only taught us about data types, for loops,..etc and gave us a big assignment so all of my information is from googling and I'm sure some of them are old outdated questions. Thanks though! — NayaCruiser, Jan 26 '21 at 18:17

score 0 · Accepted Answer · answered Jan 26 '21 at 18:12

As previously mentioned you have to use the correct constructor, which will append your text instead of overriding.

But I would suggest to do it this way:

  public static void main(String[] args) {

    for (int i = 0; i < 10; i++) {
        doSomething("test" + i);
    }

}

static void doSomething(String text) {
    try (PrintWriter test = new PrintWriter(new BufferedWriter(new FileWriter("your path", true)))) {
        test.print(text);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Here are some further informations and different approaches for your issue: How to append text to an existing file in Java?

Saving input to a file is replaced when re-running

1 Answers1