ShowopenDialog not working under actionlistener

Question

So I have been trying to make a filechooser that opens a text file and then paste the contents in a JtextArea I have defined as textArea. But I cannot get my showOpenDialog to not give an error while having the argument (this), and I researched and the answer was to fill in (null) and this does make the filechooser work but when I try to print the contents of it it also just returns null. I am using the Eclipse program hence the auto filled code. I am fairly new to Java and have no clue what is going wrong. Im really sorry if this is not the way to post things here.

JButton btnNewButton = new JButton("Bladeren");
btnNewButton.addActionListener(
    new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            JFileChooser fileChooser = new JFileChooser();
            fileChooser.setCurrentDirectory(new File(System.getProperty("user.home")));
            int result = fileChooser.showOpenDialog(this);
            if (result == JFileChooser.APPROVE_OPTION) {
                File selectedFile = fileChooser.getSelectedFile();
                System.out.println("Selected file: " + selectedFile.getAbsolutePath());
                String content = readFile(selectedFile, StandardCharsets.UTF_8);
                System.out.println(content);
                textArea.setText(content);
            }

        }

        private String readFile(File selectedFile, Charset utf8) {
            // TODO Auto-generated method stub
            return null;
        }
    }
);

Answer 1

You can look into the API that the parameter has to be from type Component . So what does this mean in your example? Which other class/interface does your class extends from or implements ?

You didn't paste the code of your readFile method but ask why it returns null? This way we cannot help you so please post the code.