PrintWriter append method not appending

The following method only writes out the latest item I have added, it does not append to previous entries. What am I doing wrong?

public void addNew() {
    try {
        PrintWriter pw = new PrintWriter(new File("persons.txt"));
        int id = Integer.parseInt(jTextField.getText());
        String name = jTextField1.getText();
        String surname = jTextField2.getText();
        Person p = new Person(id,name,surname);
        pw.append(p.toString());
        pw.append("sdf");
        pw.close();
    } catch (FileNotFoundException e) {...}
}

The fact that PrintWriter's method is called append() doesn't mean that it changes mode of the file being opened.

You need to open file in append mode as well:

PrintWriter pw = new PrintWriter(new FileOutputStream(
    new File("persons.txt"), 
    true /* append = true */)); 

Also note that file will be written in system default encoding. It's not always desired and may cause interoperability problems, you may want to specify file encoding explicitly.

PrintWriter pw = new PrintWriter(new FileOutputStream(new File("persons.txt"),true));

The true is the append flag. See documentation.

Open the file in append mode, as with the following code:

 PrintWriter pw = new PrintWriter(new FileOutputStream(new File("persons.txt"), true)); 

IMHO the accepted answer does not consider the fact that the intention is to write characters. (I know the topic is old, but since while searching for the same topic I stumbled upon this post before finding the advised solution, I am posting here.)

From the FileOutputStream docs, you use FileOutputStream when you want to print bytes.

> FileOutputStream is meant for writing streams of raw bytes such as > image data. For writing streams of characters, consider using > FileWriter.

Besides, from the BufferedWriter docs:

> Unless prompt output is required, it is advisable to wrap a > BufferedWriter around any Writer whose write() operations may be > costly, such as FileWriters and OutputStreamWriters.

Finally, the answer would be the following (as mentioned in this other StackOverFlow post):

> PrintWriter out = null; > try { > out = new PrintWriter(new BufferedWriter(new FileWriter("writePath", true))); > out.println("the text"); > }catch (IOException e) { > System.err.println(e); > }finally{ > if(out != null){ > out.close(); > } > } > Also, as of Java 7, you can use a try-with-resources statement. No > finally block is required for closing the declared resource(s) because > it is handled automatically, and is also less verbose: > > try(PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("writePath", true)))) { > out.println("the text"); > }catch (IOException e) { > System.err.println(e); > }

You need not to double buffering as shown in all other answers. You can simply do

PrintWriter pw = new PrintWriter(new FileWriter("persons.txt",true));