java update txt file content line by line

Question

I am trying to update a txt file in place, namely without creating a temp file or writing a file in a new file destination but I've tried all the solutions on stack overflow and none of these have worked so far.

It always give me an empty file as result. it simply delete all the content of the source file.

So I am trying to modify the following code, which takes two files as input, in order to take only one input (the file source) but without success.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;

public class CopyFiles {

  private static void copyFile(String sourceFileName, String destinationFileName) {

  try  (BufferedReader br = new BufferedReader(new FileReader(sourceFileName));
        PrintWriter pw = new PrintWriter(new FileWriter(destinationFileName))) {
    String line;
    while ((line = br.readLine()) != null) {
      line += " ENDING ";
      pw.println(line);
    }
  } catch (Exception e) {
    e.printStackTrace();
  }
}

public static void main(String[] args) {
  String destinationFileName = "destination.csv";
  String sourceFileName = "source.csv";
  copyFile(sourceFileName, destinationFileName);
}

}