authentication - How to prevent a window to load if it has not previously gone through the stage of login in Java? -

i have made program in java has 2 windows (jframes):

a) log-in window,

b) main window.

the correct way run program run first "log-in window" , if username , password correct, window redirects "main window", making "log-in window" dispose.

but

if runs directly "main window" (ignoring log-in stage), window run correctly without authentication...

so

how can prevent "main window" loading , running if runs directly (e.g.>> java main_window)? want program run only order (1) "log-in window" , (2) "main window".

edit

the main_window class has 1 main method below code:

public static void main(string[] args) {    eventqueue.invokelater(new runnable() {     public void run() {       try {          final main_window frame = new main_window();                     frame.setlocationrelativeto(null);         frame.setvisible(true);          frame.addwindowlistener(new windowadapter() {            public void windowclosing(windowevent e) {             torunonclose();             frame.dispose();           }          });        } catch (exception e) {         e.printstacktrace();       }      }    });  } 

suggestions:

• your login window should modal dialog, such jdialog, not jframe.
• your gui should have one main method, method calls login modal dialog first, , if successful, opens main jframe after this.

the main main method like:

   private static void createandshowgui() {       logindialog logindialog = new logindialog();       logindialog.setvisible(true);        // verify user authentic       if (logindialog.verify()) {          maingui maingui = new maingui();          maingui.setvisible(true);       }    }     public static void main(string[] args) {       swingutilities.invokelater(new runnable() {          public void run() {             createandshowgui();          }       });    } 

in example above, since logindialog modal, code below logindialog.setvisible(true) not run until dialog window no longer visible.

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regarding questions:

1) run code @ loading time of main window,

run in single 1 main method.

2) how can set , feel (later) without main method

you'll have main method, one main method.

3) how can run code when frame closes (as doing now)?

do same thing in single main method.