Thread: Getting data back from a child form

Hello everyone

I am frantically trying to learn Java and have now found myself wondering if I am passing variables back from a temporary child dialog back to the caller correctly. If somebody would be so good, I would appreciate it if you could look at my example classes and tell me if I am doing it correctly. If not, why not!

For this example, in C++ I would probably pass in a pointer and have the caller updated that way but of course Java doesn't support primitive type pointers.

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JTextField;
 
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
public class Example extends JFrame {
 
    //Instantiate the container object
      Container c = new Container();
 
    public static void main(String[] args) {
 
        Example w = new Example();
        w.initGUI();
 
    }
 
    private void initGUI(){
 
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
 
        // SETUP BASIC GUI COMPONENTS
        JPanel p = new JPanel();
        JButton b = new JButton("CLICK ME");
        final JTextField tf = new JTextField();
 
        // SETUP ACTION LISTENER
        b.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent evt){
 
                DialogHarvester dialog = new DialogHarvester(c);
                dialog.setModal(true);
                dialog.setVisible(true);
 
                tf.setText(c.userParameter);
 
                return;             
            }
        });
 
        // SIZE THEM AND ADD TO THE FORM
        tf.setPreferredSize(new Dimension(100,25));
        tf.setEditable(false);
        p.add(b);
        p.add(tf);
 
        this.add(p);
        this.setSize(200, 100);
        this.setVisible(true);
 
        return;
    }
 
}

AND

import java.awt.Dimension;
import javax.swing.JDialog;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JButton;
 
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
 
public class DialogHarvester extends JDialog{
 
    Container c;
    JTextField t;
 
    DialogHarvester(Container con){
 
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);
        c = con;
        this.initGUI();
 
    }
 
    private void initGUI(){
 
        // SETUP BASIC GUI COMPONENTS
        JPanel p = new JPanel();
        JButton b = new JButton("OK");
 
        t = new JTextField();
 
 
        // SETUP ACTION LISTENER
        b.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent evt){
                exitForm();
            }
        });
 
        // SIZE THEM AND ADD TO THE FORM
        t.setPreferredSize(new Dimension(100,25));
        p.add(t);
        p.add(b);
 
        this.add(p);
        this.setSize(100,100);
 
    }
 
    private void exitForm(){
 
        c.userParameter = t.getText();
        this.dispose();
    }
 
}

AND

public class Container {
 
    Container(){}
 
    public String userParameter;
 
}

Many thanks for reading and I thank people in advance for helping me yet again.

Regards
Nikki

Hi, thank you.

Yes, it does, works perfectly! I was really thinking about best practice.

Thank you

Thank you very much Kevin.

I'm off to do some reading....