Add item to JList from another class

[Dan Quartz]

Hi,
I have a problem that made me to spend 20hrs with no luck. Here is the problem. I have a program with 3 classes. Main, ClassA, ClassB. Main Class is just a simple main method to load JFrame in class A. In class A I got a JList and a JButton. So whenever I press this button, it loads Class B. In class B I got another button that its job is to add items to the JList in ClassA. Let's say when ever I press that button, it does Button.addElement("Item");

I made the layout but the problem is because they are in separate classes they cant link well. I guess I could not pass the instance. Anyway here is the code for each class:

Main Window:

public class main {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        JFrame frame = new ClassA();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

    }

}

ClassA:

public class ClassA extends JFrame {

        DefaultListModel<String> myList;
        JList list;

        public ClassA() {

        setSize(300,200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(2,1));

        myList = new DefaultListModel<String>();
        list = new JList(myList);


        //ClassB sendsText = new ClassB(myList, list);

        JButton find = new JButton("Find");
        find.addActionListener(new ActionListener(){

            public void actionPerformed(ActionEvent e) {
                new ClassB().setVisible(true);
            }

        });


        add(panel);
        panel.add(find);
        panel.add(list);
    }

}

ClassB:

public class ClassB extends JFrame {

    DefaultListModel<String> myList;
    JList list;
    public ClassB(DefaultListModel<String> myList, JList list){
        this.myList = myList;
        this.list = list;
    }


    public ClassB() {
        setSize(300,200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(2,1));

        JButton addMe = new JButton("Add Me");
        addMe.addActionListener(new ActionListener(){

            public void actionPerformed(ActionEvent e) {
                myList.addElement("Danial");

            }

        });

        add(panel);
        panel.add(addMe);
    }

}

So when I press the add button in classB it gives lots of errors and basically doesn't work. Any idea?

Thanks in advance.

[Rob Spoor]

Call the other ClassB constructor.

Merge the two ClassB constructors into one. In the first you only set the fields you need to set. In the second you setup the UI. You need to do both.

[Dan Quartz]

Rob Spoor wrote:Call the other ClassB constructor.

Merge the two ClassB constructors into one. In the first you only set the fields you need to set. In the second you setup the UI. You need to do both.

Wow thank you so much. Worked perfectly.