display a new jpanel in an applet

God applets just boggle my mind, but anyways. I've created a class which extends JApplet and calls a class which extends JPanel. I have a button on this JPanel class and when it is clicked, I want it to display a different JPanel.

I'm not sure how to do this.


Here's my JApplet class

Code:

---

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * NewJApplet.java
 *
 * Created on Oct 16, 2009, 6:52:11 PM
 */

package mainPackage;

import javax.swing.JApplet;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;

/**
 *
 * @author Administrator
 */
public class NewJApplet extends javax.swing.JApplet {

    /** Initializes the applet NewJApplet */
    public void init() {
        try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                public void run() {
                    Language lan = new Language();
                    setContentPane(lan);
                }
            });
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    /** This method is called from within the init() method to
    * initialize the form.
    * WARNING: Do NOT modify this code. The content of this method is
    * always regenerated by the Form Editor.
    */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 298, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 297, Short.MAX_VALUE)
        );
    }// </editor-fold>


    // Variables declaration - do not modify
    // End of variables declaration

}

---

and it calls this JPanel class

Code:

---

/*
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * Language.java
 *
 * Created on Oct 17, 2009, 2:40:54 PM
 */

package mainPackage;

/**
 *
 * @author Administrator
 */
public class Language extends javax.swing.JPanel {

    /** Creates new form Language */
    public Language() {
        initComponents();
    }

    /** This method is called from within the constructor to
    * initialize the form.
    * WARNING: Do NOT modify this code. The content of this method is
    * always regenerated by the Form Editor.
    */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        englishButton = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();

        jLabel1.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
        jLabel1.setText("Please select a language");

        englishButton.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
        englishButton.setText("English");
        englishButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                englishButtonActionPerformed(evt);
            }
        });

        jButton2.setText("jButton2");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jLabel1)
                    .addComponent(englishButton)
                    .addComponent(jButton2))
                .addContainerGap(225, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addGap(18, 18, 18)
                .addComponent(englishButton)
                .addGap(58, 58, 58)
                .addComponent(jButton2)
                .addContainerGap(148, Short.MAX_VALUE))
        );
    }// </editor-fold>

    private void englishButtonActionPerformed(java.awt.event.ActionEvent evt) {
        EnterSocial social = new EnterSocial();
        setContentPane(social);
    }


    // Variables declaration - do not modify
    private javax.swing.JButton englishButton;
    private javax.swing.JButton jButton2;
    private javax.swing.JLabel jLabel1;
    // End of variables declaration

}

---

and when the englishButton is clicked, I want it to display this JPanel class

Code:

---

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * EnterSocial.java
 *
 * Created on Oct 17, 2009, 2:29:39 PM
 */

package mainPackage;

/**
 *
 * @author Administrator
 */
public class EnterSocial extends javax.swing.JPanel {

    /** Creates new form EnterSocial */
    public EnterSocial() {
        initComponents();
    }

    /** This method is called from within the constructor to
    * initialize the form.
    * WARNING: Do NOT modify this code. The content of this method is
    * always regenerated by the Form Editor.
    */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();

        jLabel1.setText("jLabel1");

        jTextField1.setText("jTextField1");

        jButton1.setText("jButton1");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jLabel1)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(18, 18, 18)
                        .addComponent(jButton1)))
                .addContainerGap(240, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton1))
                .addContainerGap(234, Short.MAX_VALUE))
        );
    }// </editor-fold>


    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration

}

---

In the second piece of code, where it says setContentPane(social); gives an error. Anybody know how to do this?

It's all about passing and using references. for instance:

NewJApplet.java

Code:

---

public class NewJApplet extends javax.swing.JApplet {
    public void init() {
        try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                public void run() {
                    // pass a reference of the applet to the Language object
                    Language lan = new Language(NewJApplet.this);
                    setContentPane(lan);
                }
            });
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    //........

---

Language.java

Code:

---

public class Language extends javax.swing.JPanel {
    private NewJApplet newapplet;
   
    Language( NewJApplet newapplet) {
        this.newapplet = newapplet;
        initComponents();
    }
 
    //.......

    private void englishButtonActionPerformed(java.awt.event.ActionEvent evt) {
        EnterSocial social = new EnterSocial();
        newapplet.setContentPane(social);
        social.revalidate();
        newapplet.repaint();
    }

---

Myself, I'd not bother with all of this but instead use a CardLayout.

For the record: I thoroughly hate NetBeans-generated code. It's ugly, bloated, and impossible to read and quickly understand what it's doing. In the future, if possible, you would be better off posting non-NetBeans generated code. This way more folks can compile your code, and can read it. All you need to post is code that creates a JPanel with a button and label which would replace 200 lines with 10 max.

For instance, here's a CardLayout example. See how much shorter and more understandable the code is without the NetBeans-generated junk:

Code:

---

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class NewJApplet extends JApplet {
  public static final String PANEL1 = "Panel 1";
  public static final String PANEL2 = "Panel 2";
  private CardLayout cardlayout = new CardLayout();
  private JPanel mainPanel = new JPanel(cardlayout);
 
  public void init() {
      try {
        javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
            public void run() {
              createGUI();
            }
        });
      }
      catch (Exception e) {
        System.err.println("createGUI didn't successfully complete");
      }
  }

  private void createGUI() {
      Panel1 panel1 = new Panel1(this);
      Panel2 panel2 = new Panel2(this);
     
      mainPanel.add(panel1, PANEL1);
      mainPanel.add(panel2, PANEL2);
      getContentPane().add(mainPanel);
  }
 
  public void swapCard(String name) {
      cardlayout.show(mainPanel, name);
  }
}

class Panel1 extends JPanel {
  public Panel1(final NewJApplet newapplet) {
      JButton selectEnglish = new JButton("English");
      selectEnglish.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent e) {
            newapplet.swapCard(NewJApplet.PANEL2);
        }
      });
      add(new JLabel("Please Select a Language:"));
      add(selectEnglish);
  }
}

class Panel2 extends JPanel {
  public Panel2(final NewJApplet newapplet) {
      add(new JLabel("Panel 2"));
  }
 
}

---

Thanks your code worked great!

CardLayout does look alot cleaner.

I have another question now. If I want to now call another JPanel, how would I do that. If i copy this

Code:

---

private NewJApplet newapplet;
   
   
    /** Creates new form Language */
    public Language(NewJApplet newapplet){
        this.newapplet = newapplet;
        initComponents();
    }

---

into my EnterSocial class, I get an error in my Language class at the line
EnterSocial social = new EnterSocial();

Code:

---

private void englishButtonActionPerformed(java.awt.event.ActionEvent evt) {                                             
        EnterSocial social = new EnterSocial();
        newapplet.setContentPane(social);
        social.revalidate();
        newapplet.repaint();
    }

---

Do you know why this is? Am i trying to instantiate something twice?

No idea. You're far better off creating a small non-netbeans class that compiles and demonstrates your error.