在面板之间传递信息吗？

Question

Im using swing in java to make a quiz for my coursework. I have made my main class, a tabbed frame that holds separate jpanels as tabs for example the login page, and im using sqlite to get my data. However Im struggling to see how i can communicate between say my login jpanel and my main class.

mainJFrame.addWindowListener(new WindowAdapter() {
        public void windowActivated(WindowEvent arg0) {
            LoginPanel loginEntry = new LoginPanel();
            welcomePanel.add(loginEntry);
            welcomePanel.setBounds(0,0,728,390);

//So here i would like an if statement so that on successful login, the other tabs are added and can be seen. But are not available if you are not logged in.

                tabbedPane.addTab("Quick Guide", null, quickGuidePanel, null);
                tabbedPane.addTab("Examples", null, examplePanel, null);
                tabbedPane.addTab("Run Quiz", null, runQuizPanel, null);
                tabbedPane.addTab("Exams", null, examPanel, null);
                tabbedPane.addTab("View Performance", null, viewPerfPanel, null);
                tabbedPane.addTab("Settings", null, settingsPanel, null);

        }
    });

I tried creating a getter and setter and tried to getSuccessfulLogin() but that wasn't working :(

thanks

Answer 1

I good way to populate your loginInformation in the Application would be a Singleton Pattern. For example:

public class AuthService {
   private static AuthService myInstance;

   private User currentUser;
   ...

   private AuthService() {
       // Constructor is private. The Object can only be instanciated by getInstance()
   }

   public static AuthService getInstance() {
      if (myInstance == null) {
         myInstance = new AuthService();
      }

      return myInstance;
   }

   public User getCurrentUser()
   ...


   public void setLoggedInUser(User user)
   ...

   public User login(String userName, String password)
   ...

}

Via the static getInstance()-method you can get an Instance of exact the same object everywhere in your Appliaction without the need to carry the Object trough all constructros or methods. You can hold all your authentification-related Data there and even some Methods, that do the login-work. The getCurrentUser() could return null if no succelsful logged in user exists.

If it is possible to login from more then one client at the same time you will need to hold different UserInformations for different sessions in your AuthService.

Answer 2

Change the line:

LoginPanel loginEntry = new LoginPanel();

to

LoginPanel loginEntry = new LoginPanel(MainJFrame.this);

and inside the login function:

if (success) {
    //add the TabbedPane
    mainJFrame.add(tabbedPane);
} else {
    // do not add the TabbePane
}

Answer 3

For checking if the log in is successful you could create a static variable that holds a Boolean whether the current user is successfully logged in. Static has the meaning that it is accessible throughout the whole program.

static Boolean isLoggedIn

You probably see that you need to set that variable somewhere, and read it somewhere to allow 'communication'

For more information it is better to assign methods within the tabs that inform each other. This would be more event/action based programming where you keep the responsibilities of each part of your program straight.

As @Adel noted, you could link the main frame to the login panel. This has the advantage that you keep it tighter, but this also might have to problem that if you have more tabs you want to communicate with each other, that you need to inform all panels which panels there are.

Answer 4

you can create a static method. hold login info!!