Accessing objects made in main method from other classes

Question

Hey I'm trying to access an object I've made in the main method from another class but when I reference it in the other class it is not recognised. After some research I think this has something to do with access modifiers but I have tried making the object public only for a comment to appear saying "remove invalid modifier". Any pointers?

Sorry about this being so basic but I'm only a beginner and I'm finding this stuff quite tough.

Sorry for not mentioning! I am writing in Java. This is what I have:

public static void main(String[] args) {

    Mainframe mainframe = new Mainframe();
    mainframe.initialiseMF();       
    LoginPanel lp = new LoginPanel();
    mainframe.add(lp);
}

public class Mainframe extends JFrame {

public Mainframe () {
    // Set size of mainframe
    setBounds(0, 0, 500, 500);

}

public void initialiseMF (){
    // Get the size of the screen
    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();

    // Determine the new location of the mainframe
    int w = getSize().width;
    int h = getSize().height;
    int x = (dim.width-w)/2;
    int y = (dim.height-h)/2;

    // Move the mainframe
    setLocation(x, y);
    setVisible(true);
}

}

I am trying to do this statement in another class :

Container content = mainframe.getContentPane();   

Answer 1

Remember, the mainframe object is local to the main() method which is static. You cannot access it outside the class.

Probably this would be a bit cleaner.

public class Mainframe extends JFrame{
     public Mainframe(){
          initialiseMF ();
     }

     public void initialiseMF (){
          //do ur inits here
     }

}

Then do this,

public class TheOtherClass{

    private Mainframe mainFrame;

    public TheOtherClass(){
        mainFrame = MainFrame.mainFrame; //although I would not suggest this, it will avoid the Main.mainFrame call
    }

    public void otherMethodFromOtherClass(JFrame mainFrame){
        Container content = mainFrame.getConentPane();
    }
}