Java Object Oriented function calling between classes

Question

I ma new in OOD and working on Academic project. I am facing a problem while programming it.

The scenario is that I have a main class in which I have made an object of "login" class and call its function.

Now in that "login" class function I create an object of jFrame class to show a login view, where user enters the login info and press login button.

Now I want that when user press login button I should pass that info to an authenticate function in my "login" class.

The problem is that how can I call that function (its a non-static function), and upon invalid info call a function of jFrame class to show error message.

And I want to do this function calling all over in my project.

Answer 1

Maybe you need to redesign your program a bit. The login class should not be creating a JFrame. Let the login class concentrate on authenticating users and its related functions. So something like this:

  public class Login{

      public boolean authenticate(String uname, String pword){
           return .......
      }

  }

Whenever you need to use the functions of Login, you can instantiate it and call the function. You can create a JFrame for instance that prompts the user for username and password and in the action of the button:

         loginBtn.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e){

                      Login login = new Login();
                      if(login.authenticate(txtUname.getText(), txtPWord.getText())){
                              //display success on JFrame
                      }else{
                              //display failure on JFrame
                      }
                }
          });

Where txtUname and txtPWord may be 2 JTextFields on you JFrame, and lginBtn may be a button on your JFrame.

If you need to perform the same function somewhere else then you instantiate Login again and call the function.

Answer 2

Here is a nice & working example of How-to-create-a-login-form-in-javax.swing

A swing tutorial link for Java Beginner Swing