Java Swing Login Form

[sehudson]

I am using swing to build an application, and want to have a login screen.

I basically have 2 panel classes, one being the main page of the application, and the other being the login screen panel.

My question is, how do I (in java) do a "hold", type of action.

In other words, In my main program, before I do an initComponents, I do a loginscreen.setVisible(true), which displays the login to the user, and then based on whether or not they put in the correct login. I am going to set a boolean up to be true or false, which I guess will be interpreted by my main applcationView class.

But how would I create a "pause" after I set the screen visible to wait on the user to hit the "submit" button, at which point I want to check the login, and then run the rest of the program.

I saw something about wait and notify, but was unsure of how to use them, or if this was the right approach.

Thanks

[Fubarable]

One way is to make the login screen a modal JDialog and not display the main JFrame until after it returns and it's fields are checked and found to comply with your login restraints.

[sehudson]

actually, i meant to say that the login screen is actually a jdialog.

Here is the first part of the code in my main applicationView class:

public InventoryView(SingleFrameApplication app) {
super(app);
F = new JFrame();
db = new DatabaseConn(this);
//Connect to the Database.
db.Connect();
Login = new LoginScreen(F, true, db, this);
Login.setVisible(true);
initComponents();


so basically, I want there to be a pause between the login.setVisible(true), and the init components, which basically waits for a response from the jdialog, on whether or not the conditions are met after they click OK on the login screen.

[Fubarable]

A modal JDialog will do just that. For instance a JOptionPane is in fact a modal JDialog, so it can demonstrate this well:

import java.awt.Dimension;
import java.awt.GridLayout;

import javax.swing.*;

public class LoginTest {
   private static void createAndShowUI() {
      LoginPanel login = new LoginPanel();
      int response = JOptionPane.showConfirmDialog(null, login, "Please Enter Name and Password", 
               JOptionPane.OK_CANCEL_OPTION, JOptionPane.PLAIN_MESSAGE);
      
      if (response == JOptionPane.OK_OPTION) {
         String name = login.getName();
         String pWord = login.getPassword();
         
         if (name.equals("Fubar") && pWord.equals("Snafu")) {
            JFrame frame = new JFrame("Main Application");
            JLabel label = new JLabel("Main Application", SwingConstants.CENTER);
            label.setPreferredSize(new Dimension(400, 300));
            frame.getContentPane().add(label);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
         }
         
         else {
            String msg = "Incorrect name and password. \n(try Fubar and Snafu)";
            JOptionPane.showMessageDialog(null, msg);
         }
      }
      
   }

   public static void main(String[] args) {
      java.awt.EventQueue.invokeLater(new Runnable() {
         public void run() {
            createAndShowUI();
         }
      });
   }
}

class LoginPanel extends JPanel {
   private JTextField nameField = new JTextField(10);
   private JPasswordField passwordField = new JPasswordField(10);
   
   public LoginPanel() {
      setLayout(new GridLayout(2, 2, 5, 5)); // change to GridBagLayout later
      add(new JLabel("Name:"));
      add(nameField);
      add(new JLabel("Password:"));
      add(passwordField);
   }
   
   public String getName() {
      return nameField.getText();
   }
   
   public String getPassword() {
      return new String(passwordField.getPassword()); // shouldn't do this!
   }
}

[sehudson]

so I tried to create a string in the login class called passOrFail, and basically whenever they login, the string will be pass or "fail". And then in my main application class, right after I make the login screen visible, I say

if (loginscreen.passorfail().equals("fail"){
system.out.println("wrong login")
}
else{
initComponents..
etc
etc
etc.
}


but I get the error, notStatic method "passorfail" cannot be referenced from a static context.

[Fubarable]

but I get the error, notStatic method "passorfail" cannot be referenced from a static context.

So don't reference it in a static way -- create an object and use this object. Knowledge of static and non-static is a bit of a prerequisite for coding with Swing, and so you might want to hit some of the basic tutorials about object creation first before moving on here.