How do I Prompt the user to enter a password before entering the main program?

Question

What I need to do is to prompt the user with a username and password (authentication is done locally) and if it checks out, the user would then be able to access the main pr

Answer 1

You can simply add a static block to your program where you will do your authentication, this static block is always executed before the main method. If the user is not valid go with

System.exit(0);

to exit the program. Else the program will start execution as usual.

Here is one sample program to give you some idea :

import java.awt.Color;
import javax.swing.*;

public class Validation extends JFrame
{
    private static Validation valid = new Validation();
    static
    {
        String choice = JOptionPane.showInputDialog(valid, "Enter Password", "Password", JOptionPane.PLAIN_MESSAGE);
        if ((choice == null) || ((choice != null) && !(choice.equals("password"))))
            System.exit(0);
    }

    private static void createAndDisplayGUI()
    {
        valid.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        valid.setLocationRelativeTo(null);

        valid.getContentPane().setBackground(Color.YELLOW);

        valid.setSize(200, 200);
        valid.setVisible(true);
    }
    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndDisplayGUI();
            }
        });
    }
}