Copying a value from 1 JPanel to another

[Steve Gebert]

Hi - I am having a heck of a time with what I am sure is a simple issue. I have a frame with a tabbed pane. In this pane I have placed two JPanels that are separate classes. I am trying to copy the value of a text field from one panel to the other based on the button press action on the second. I seem to have missed the concept of visibility here. What I am trying to do is pretty simple in VB etc but for the life of me I can't seem to get it here. I need this so that I can do updates on records in a database and promulgate the record id's. Any help woudl be greatly appreciated. Thanks in advance.


Here is the code for the frame that holds the tabbed panel etc;

import javax.swing.JFrame;
import java.awt.Dimension;
import javax.swing.JTabbedPane;
import java.awt.Rectangle;
 
public class MainFrame extends JFrame 
{
  private JTabbedPane mainTab = new JTabbedPane();
  private PanelA myPanelA = new PanelA();
  private PanelB myPanelB = new PanelB();
 
  public MainFrame()
  {
    try
    {
      jbInit();
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
 
  }
 
  private void jbInit() throws Exception
  {
    this.getContentPane().setLayout(null);
    this.setSize(new Dimension(807, 459));
    mainTab.setBounds(new Rectangle(42, 72, 723, 294));
    mainTab.addTab("A", myPanelA);
    mainTab.addTab("B", myPanelB);
    this.getContentPane().add(mainTab, null);
  }
}

Here is the code for the 1st panel

  
import javax.swing.JPanel;
import javax.swing.JTextField;
import java.awt.Rectangle;
 
public class PanelA extends JPanel 
{
  public JTextField test_txt = new JTextField();
 
  public PanelA()
  {
    try
    {
      jbInit();
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
 
  }
 
  private void jbInit() throws Exception
  {
    this.setLayout(null);
    test_txt.setText("This is a test");
    test_txt.setBounds(new Rectangle(75, 45, 222, 36));
    this.add(test_txt, null);
  }
}

And here is the code for the second and problematic panel;

  
import javax.swing.JPanel;
import javax.swing.JTextField;
import java.awt.Rectangle;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
 
public class PanelB extends JPanel 
{
  private JTextField secondTest_txt = new JTextField();
  private JButton pressMe_btn = new JButton();
  // If I add the following it will compile but does not reference the real panelA
  //public PanelA myPanelA;
  // or this which gives me nothing because it is a new empty panel reference
  //public PanelA myPanelA = new PanelA();
  
  public PanelB()
  {
    try
    {
      jbInit();
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
 
  }
 
  private void jbInit() throws Exception
  {
    this.setLayout(null);
    secondTest_txt.setBounds(new Rectangle(84, 36, 159, 48));
    pressMe_btn.setText("Press Me");
    pressMe_btn.setBounds(new Rectangle(84, 117, 159, 48));
    pressMe_btn.addActionListener(new ActionListener()
      {
        public void actionPerformed(ActionEvent e)
        {
          pressMe_btn_actionPerformed(e);
        }
      });
    this.add(pressMe_btn, null);
    this.add(secondTest_txt, null);
  }
 
  private void pressMe_btn_actionPerformed(ActionEvent e)
  {
    // If I try the following I get a static context error
    //String myString = PanelA.test_txt.getText();
    
    String myString = myPanelA.test_txt.getText();
    secondTest_txt.setText("");
  }
}

And finally here is the code for the bootstrap program that contains my Main;

  
import java.awt.Frame;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.UIManager;
import java.awt.Dimension;
import java.awt.Toolkit;
 
public class VisTest 
{
  public VisTest()
  {
    Frame frame = new MainFrame();
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    Dimension frameSize = frame.getSize();
    if (frameSize.height > screenSize.height)
    {
      frameSize.height = screenSize.height;
    }
    if (frameSize.width > screenSize.width)
    {
      frameSize.width = screenSize.width;
    }
    frame.setLocation((screenSize.width - frameSize.width) / 2, (screenSize.height - frameSize.height) / 2);
    frame.addWindowListener(new WindowAdapter()
      {
        public void windowClosing(WindowEvent e)
        {
          System.exit(0);
        }
      });
    frame.setVisible(true);
  }
 
  /**
   * 
   * @param args
   */
  public static void main(String[] args)
  {
    try
    {
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
 
    new VisTest();
  }
}

[Michael Dunn]

class MainFrame extends JFrame
{
  private JTabbedPane mainTab = new JTabbedPane();
  private PanelA myPanelA = new PanelA();
  private PanelB myPanelB = new PanelB(myPanelA);//<-------------------

class PanelB extends JPanel
{
  private JTextField secondTest_txt = new JTextField();
  private JButton pressMe_btn = new JButton();
  PanelA panelA;//<----------------
  public PanelB(PanelA pa)//<----------------
  {
    panelA = pa;//<----------------
    try
    {
      jbInit();
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
  }
  private void jbInit() throws Exception
  {
    this.setLayout(null);
    secondTest_txt.setBounds(new Rectangle(84, 36, 159, 48));
    pressMe_btn.setText("Press Me");
    pressMe_btn.setBounds(new Rectangle(84, 117, 159, 48));
    pressMe_btn.addActionListener(new ActionListener()
      {
        public void actionPerformed(ActionEvent e)
        {
          pressMe_btn_actionPerformed(e);
        }
      });
    this.add(pressMe_btn, null);
    this.add(secondTest_txt, null);
  }
 
  private void pressMe_btn_actionPerformed(ActionEvent e)
  {
    String myString = panelA.test_txt.getText();//<----------------
    secondTest_txt.setText(myString);
  }
}

[Scott Delap]

Sounds like you need some sort of shared "controller" or data model behind the panels. You would share this class and then have the panel set a value on it. It would then update any listeners (one which could be your other panel).

Scott Delap
ClientJava.com
Desktop Java Live

[Steve Gebert]

Thanks guys - I am on the track of it now. One each of the panels I wrote the following;

public void setParent(MainFrame myMainFrame)
{
this.myMainFrame = myMainFrame;
}

and on the frame I added;
myPanelA.setParent(this);
myPanelB.setParent(this);

and on PanelB I added this line;
secondTest_txt.setText(myMainFrame.myPanelA.test_txt.getText());

This gives me a reference to each panel. Works great. Thanks