Calling an Object

[67726e]

Ok, if I have an object A, how would I go about calling it from object B?

[Zack]

Be more specific.

Does A have methods? Do you want to call a constructor?

public class B {
    public B() {
        A a = new A(); // calls constructor
        a.someMethod(); // calls method "someMethod"
    }
}

Something like that?

[Fubarable]

Do you mean "class" A and B, not object? If so, then

class A {
   public void someMethodOfA() {
      System.out.println("in someMethodOfA");
   }
}

class B {
   private A aObject = new A();

   public void someMethod() {
      aObject.someMethodOfA();
   }
}

If this is not what you meant, then you will need to clarify your question a lot.

[67726e]

Let me give a more detailed exmaple:

public class RSS {
     public static void main(String[] args) {
          Frame frame = new Frame();
          frame.setDeafultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
          frame.setResizable(false);
     }
}

class Frame extends JFrame {
     public Frame() {
          setBounds(/* location, size */);
          setTitle("Some Text");

          Container contentPane = getContentPane();
          JPanel panel = new Panel();
          contentPane.add(panel);
          panel.setLayout(null);
     }
}

class Panel extends JPanel {
     public Panel() {
          Menu menu = new Menu();
          add(menu);

          text = new JTextField();
          text.setBounds(/* Size it, position it */);
          add(text);
     }

     public String getText() {
          return text.getText();
     }

     private JTextField text;
}

class Menu extends JMenuBar {
     public Menu() {
          setBounds(/* locate, size it */);
          
          JMenu file = new JMenu("File");
          JMenuItem item = new JMenuItem("Do Stuff");
          file.add(item);

          item.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent event) {
                    String str = panel.getText();
               }
          });
     }
}

The code gives me the error:

RSS.java:53: cannot find symbol
symbol: variable panel
String str = panel.getText();
^
1 error

I know I can do it statically by calling Panel.getText(); and making text a static JTextField, but is there a way to do it they way I have above?

[Fubarable]

Pass a reference of the Panel object into Menu via a constructor parameter, and call the method off of that.

e.g.,

class Panel extends JPanel {
   public Panel() {
      Menu menu = new Menu(this); //!! *** note change ****
      add(menu);

      // .... code deleted
   }

   //...   
}

class Menu extends JMenuBar {
   Panel myPanel;

   public Menu(Panel p) {
      myPanel = p; // get your reference and assign it.
      // ....

      item.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent event) {
            // !! String str = panel.getText();
            String str = myPanel.getText();
         }
      });
   }
}

[crikey]

make myPanel static. Then it should work

[Fubarable]

make myPanel static. Then it should work

To the original poster, please do not follow this route as it will destroy any object-oriented abilities of your program.

To crikey: Please stop giving out bad advice (as here secondary-jframe). This is worse than giving no advice at all. And don't get me wrong, I'm not saying I'm perfect, far from it, but at least I state when I don't know what the heck I'm talking about or when I'm guessing.

[67726e]

Passing references! I do that all the time with event delegation in jQuery yet I never realize it is the same concept. Thank you so much!

[alacn]

To the original poster, please do not follow this route as it will destroy any object-oriented abilities of your program.

To crikey: Please stop giving out bad advice (as here secondary-jframe). This is worse than giving no advice at all. And don't get me wrong, I'm not saying I'm perfect, far from it, but at least I state when I don't know what the heck I'm talking about or when I'm guessing.

Fubarable, could you elaborate some more on your comments about declaring things static? i'm very interested in hearing your opinions on this.