Update MolecularDatabaseGUI.java

import java.io.*;

import java.net.*;

public class MolecularDatabaseGUI extends JFrame {

public class GUI extends JFrame {

    private JTextArea outputTextArea;

    private JButton chooseFileButton;

    private JButton addMoleculeButton;

    /**

     * GUI constructor

     */

    public MolecularDatabaseGUI() {

    public GUI() {

        // Set up the JFrame

        setTitle("Molecule Database");

        setDefaultCloseOperation(EXIT_ON_CLOSE);

                // Create a file chooser

                JFileChooser fileChooser = new JFileChooser();

                fileChooser.setDialogTitle("Choose a file");

                int result = fileChooser.showOpenDialog(MolecularDatabaseGUI.this);

                int result = fileChooser.showOpenDialog(GUI.this);

                // If a file is selected, set its path in the molecule path field

                if (result == JFileChooser.APPROVE_OPTION) {

                    File selectedFile = fileChooser.getSelectedFile();

        SwingUtilities.invokeLater(new Runnable() {

            @Override

            public void run() {

                MolecularDatabaseGUI gui = new MolecularDatabaseGUI();

                GUI gui = new GUI();

            }

        });

    }