Simple Password Vault

I made a simple password vault in Java and I was wondering if anyone had any input on it. The code works fine, I just wanted to know if there are any improvements that could be made.

import javax.swing.*;
import javax.swing.table.*;
import java.awt.event.*;

public class PasswordVault implements ActionListener
{
    static String masterPassword, enteredPassword;
    JFrame masterPasswordFrame, passwordVault;
    JPasswordField masterPasswordField;
    JTable passwordTable;
    Object[] columnNames = {"Name of Application", "Application Password", "Description"};
    Object[] rowData = new Object[3];
    JTextField appName, appPass, appDesc;
    JButton add, delete, update;
    JLabel nameOfApp, passOfApp, descOfApp;

    public static void  main(String[] args) 
    {   
        String name = JOptionPane.showInputDialog("What is your name?");
        masterPassword = JOptionPane.showInputDialog("Hello, " + name + ". " + "What would you like your master password to be?");

        new PasswordVault();
    }

    public PasswordVault()
    {
        masterPasswordFrame = new JFrame("Master Password");
        masterPasswordFrame.setSize(400,100);
        masterPasswordFrame.setLocationRelativeTo(null);
        masterPasswordFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel masterPasswordPanel = new JPanel();

        masterPasswordField = new JPasswordField(10);
        masterPasswordField.setEchoChar('*');
        JLabel passwordLabel = new JLabel("Enter Password: ");
        JButton okayButton = new JButton("Check");
        okayButton.addActionListener(this);

        masterPasswordPanel.add(passwordLabel);
        masterPasswordPanel.add(masterPasswordField);
        masterPasswordPanel.add(okayButton);

        masterPasswordFrame.add(masterPasswordPanel);
        masterPasswordFrame.setVisible(true);
        masterPasswordFrame.pack();

        enteredPassword = new String(masterPasswordField.getPassword());    

        passwordVault = new JFrame("Password Vault");
        passwordTable = new JTable();

        DefaultTableModel tableModel = new DefaultTableModel();
        tableModel.setColumnIdentifiers(columnNames);
        passwordTable.setModel(tableModel);

        appName = new JTextField();
        appPass = new JTextField();
        appDesc = new JTextField();

        add = new JButton("Add");
        delete = new JButton("Delete");
        update = new JButton("Update");  

        nameOfApp = new JLabel("App Name: ");
        passOfApp = new JLabel("App password: ");
        descOfApp = new JLabel("Description: ");

        appName.setBounds(400, 220, 100, 25);
        appPass.setBounds(400, 250, 100, 25);
        appDesc.setBounds(400, 280, 100, 25);

        add.setBounds(530, 220, 100, 25);
        update.setBounds(530, 250, 100, 25);
        delete.setBounds(530, 280, 100, 25);

        JScrollPane scrollPane = new JScrollPane(passwordTable);
        scrollPane.setBounds(0, 0, 1000, 200);
        passwordVault.setLayout(null);
        passwordVault.add(scrollPane);

        passwordVault.add(nameOfApp);
        passwordVault.add(passOfApp);
        passwordVault.add(descOfApp);

        passwordVault.add(appName);
        passwordVault.add(appPass);
        passwordVault.add(appDesc);

        passwordVault.add(add);
        passwordVault.add(update);
        passwordVault.add(delete);

        add.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e) 
            {
                rowData[0] = appName.getText();
                rowData[1] = appPass.getText();
                rowData[2] = appDesc.getText();

                tableModel.addRow(rowData);

                appName.setText("");
                appPass.setText("");
                appDesc.setText("");
            }
        });

        update.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e) 
            {
                int i = passwordTable.getSelectedRow();
                if(i >= 0) 
                {
                   tableModel.setValueAt(appName.getText(), i, 0);
                   tableModel.setValueAt(appPass.getText(), i, 1);
                   tableModel.setValueAt(appDesc.getText(), i, 2);

                   appName.setText("");
                   appPass.setText("");
                   appDesc.setText("");
                }
                else
                {
                    JOptionPane.showMessageDialog(null, "Update Error");
                }
            }
        });

        delete.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e) 
            {
                int i = passwordTable.getSelectedRow();
                if(i >= 0)
                {
                    tableModel.removeRow(i);

                    appName.setText("");
                    appPass.setText("");
                    appDesc.setText("");
                }
                else
                {
                    JOptionPane.showMessageDialog(null, "Delete Error");
                }
            }
        });

        passwordTable.addMouseListener(new MouseAdapter()
        {
        public void mouseClicked(MouseEvent e)
        { 
            int i = passwordTable.getSelectedRow();

            appName.setText(tableModel.getValueAt(i, 0).toString());
            appPass.setText(tableModel.getValueAt(i, 1).toString());
            appDesc.setText(tableModel.getValueAt(i, 2).toString());
        }
        });

        passwordVault.setSize(1000,500);
        passwordVault.setLocationRelativeTo(null);
        passwordVault.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void actionPerformed(ActionEvent event)
    {
        if(new String(masterPasswordField.getPassword()).equals(masterPassword))
        {
            masterPasswordFrame.setVisible(false);
            passwordVault.setVisible(true);
        }
        else
        {
            JOptionPane.showMessageDialog(null, "Password Incorrect. Please Try Again.");
        }
    }
}

Some things that caught my eye:

you don’t seem to have any persistent storage just in memory. I believe you would get more versatility by implementing external persistent storage. The storage can be in several different formats, physical file on disk, a database, cloud storage.

In line with that, it is usually not a very good idea to store passwords as literal strings. This leaves you prone to hacking. I would suggest looking at the Cryptography api.

Separate the vault from the GUI. What happens if you decide to run the vault from a server in a webpage or as a console application? You basically have to start over again.