JFrames and JPanels

Question

Hmm, I appear to be running into an odd problem here, that I believe I once solved, but for the life of me cannot remember. I have a JFrame, with a JPanel in it, and I attempt to add another JPanel to the existing JPanel. However, nothing shows up. I've placed with calling setVisible() & repaint(), but still a no go.

Anyone care to take a crack at this?

Here's my code:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package bakarangerx;
import javax.swing.*;
import java.awt.*;
/**
 *
 * @author Ryan
 */
public class MainForm extends javax.swing.JFrame {

    /**
     * Creates new form MainForm
     */
    public MainForm() {
        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() {

        FileChooser_Open = new javax.swing.JFileChooser();
        FileChooser_Save = new javax.swing.JFileChooser();
        Panel_Main = new javax.swing.JPanel();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenu1 = new javax.swing.JMenu();
        MenuItem_New = new javax.swing.JMenuItem();
        MenuItem_Open = new javax.swing.JMenuItem();
        MenuItem_Save = new javax.swing.JMenuItem();
        jMenu2 = new javax.swing.JMenu();

        FileChooser_Open.setDialogTitle("Open BakaRangerX File...");
        FileChooser_Open.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                FileChooser_OpenMouseClicked(evt);
            }
        });

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        Panel_Main.setLayout(new java.awt.GridLayout());

        jMenu1.setText("File");

        MenuItem_New.setText("New");
        MenuItem_New.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                MenuItem_NewMouseClicked(evt);
            }
        });
        jMenu1.add(MenuItem_New);

        MenuItem_Open.setText("Open");
        MenuItem_Open.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                MenuItem_OpenMouseClicked(evt);
            }
        });
        MenuItem_Open.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                MenuItem_OpenActionPerformed(evt);
            }
        });
        jMenu1.add(MenuItem_Open);

        MenuItem_Save.setText("Save");
        MenuItem_Save.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                MenuItem_SaveMouseClicked(evt);
            }
        });
        jMenu1.add(MenuItem_Save);

        jMenuBar1.add(jMenu1);

        jMenu2.setText("Edit");
        jMenuBar1.add(jMenu2);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(Panel_Main, javax.swing.GroupLayout.DEFAULT_SIZE, 788, Short.MAX_VALUE)
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(Panel_Main, javax.swing.GroupLayout.DEFAULT_SIZE, 459, Short.MAX_VALUE)
                .addContainerGap())
        );

        pack();
    }// </editor-fold>

    private void MenuItem_OpenActionPerformed(java.awt.event.ActionEvent evt) {                                              
        //FileChooser_Open.showOpenDialog(this);
        ExaminerPanel newPanel = new ExaminerPanel();
        newPanel.setMinimumSize(new Dimension(200, 200));
        newPanel.setVisible(true);
        Panel_Main.setVisible(true);
        Panel_Main.add(newPanel);
        newPanel.repaint();
        Panel_Main.repaint();
        this.repaint();

    }                                             

    private void MenuItem_NewMouseClicked(java.awt.event.MouseEvent evt) {                                          
        // TODO add your handling code here:
    }                                         

    private void MenuItem_SaveMouseClicked(java.awt.event.MouseEvent evt) {                                           
        // TODO add your handling code here:
    }                                          

    private void MenuItem_OpenMouseClicked(java.awt.event.MouseEvent evt) {                                           
        // TODO add your handling code here:
    }                                          

    private void FileChooser_OpenMouseClicked(java.awt.event.MouseEvent evt) {                                              
        if(!FileChooser_Open.getSelectedFile().equals(null)) 
        {



        }
    }                                             

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(MainForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(MainForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(MainForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(MainForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new MainForm().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JFileChooser FileChooser_Open;
    private javax.swing.JFileChooser FileChooser_Save;
    private javax.swing.JMenuItem MenuItem_New;
    private javax.swing.JMenuItem MenuItem_Open;
    private javax.swing.JMenuItem MenuItem_Save;
    private javax.swing.JPanel Panel_Main;
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenuBar jMenuBar1;
    // End of variables declaration
}




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

/**
 *
 * @author Ryan
 */
public class ExaminerPanel extends javax.swing.JPanel {

    /**
     * Creates new form Examiner
     */
    public ExaminerPanel() {
        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();
        jLabel2 = new javax.swing.JLabel();
        Button_Previous = new javax.swing.JButton();
        Button_Next = new javax.swing.JButton();
        Button_Check = new javax.swing.JButton();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        TextArea_CorrectAnswer = new javax.swing.JTextArea();
        jScrollPane2 = new javax.swing.JScrollPane();
        TextArea_Question = new javax.swing.JTextArea();
        jLabel5 = new javax.swing.JLabel();
        jScrollPane3 = new javax.swing.JScrollPane();
        TextArea_Answer = new javax.swing.JTextArea();
        jLabel6 = new javax.swing.JLabel();
        jLabel7 = new javax.swing.JLabel();
        jLabel8 = new javax.swing.JLabel();
        jLabel9 = new javax.swing.JLabel();
        jLabel10 = new javax.swing.JLabel();
        jLabel11 = new javax.swing.JLabel();
        jLabel12 = new javax.swing.JLabel();
        jLabel13 = new javax.swing.JLabel();
        jLabel14 = new javax.swing.JLabel();
        jLabel15 = new javax.swing.JLabel();

        jLabel1.setText("Question");

        jLabel2.setText("Correct Answer");

        Button_Previous.setText("Previous");

        Button_Next.setText("Next");

        Button_Check.setText("Check");

        jLabel3.setText("Wrong");

        jLabel4.setText("Right");

        TextArea_CorrectAnswer.setColumns(20);
        TextArea_CorrectAnswer.setRows(5);
        jScrollPane1.setViewportView(TextArea_CorrectAnswer);

        TextArea_Question.setColumns(20);
        TextArea_Question.setRows(5);
        jScrollPane2.setViewportView(TextArea_Question);

        jLabel5.setText("Answer");

        TextArea_Answer.setColumns(20);
        TextArea_Answer.setRows(5);
        jScrollPane3.setViewportView(TextArea_Answer);

        jLabel6.setText("Total Time");

        jLabel7.setText("Time");

        jLabel8.setText("jLabel8");

        jLabel9.setText("jLabel9");

        jLabel10.setText("jLabel10");

        jLabel11.setText("jLabel11");

        jLabel12.setText("jLabel12");

        jLabel13.setText("Grade");

        jLabel14.setText("jLabel14");

        jLabel15.setText("%");

        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.TRAILING)
                    .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel2)
                            .addComponent(jLabel1))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jScrollPane2)
                            .addComponent(jScrollPane1)))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(0, 0, Short.MAX_VALUE)
                        .addComponent(jLabel13)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel12)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel9)
                        .addGap(18, 18, 18)
                        .addComponent(jLabel4)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel11)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel7)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel10))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                .addComponent(jLabel5)
                                .addGap(57, 57, 57)
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                    .addGroup(layout.createSequentialGroup()
                                        .addComponent(Button_Previous)
                                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                        .addComponent(Button_Next))
                                    .addComponent(jScrollPane3)))
                            .addGroup(layout.createSequentialGroup()
                                .addGap(0, 0, Short.MAX_VALUE)
                                .addComponent(Button_Check)))
                        .addGap(19, 19, 19))
                    .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                        .addComponent(jLabel6)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel8)
                        .addGap(76, 76, 76)))
                .addContainerGap())
            .addGroup(layout.createSequentialGroup()
                .addGap(318, 318, 318)
                .addComponent(jLabel15)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jLabel14)
                .addContainerGap(430, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel6)
                    .addComponent(jLabel8))
                .addGap(16, 16, 16)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel14)
                    .addComponent(jLabel15))
                .addGap(17, 17, 17)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel3)
                    .addComponent(jLabel4)
                    .addComponent(jLabel7)
                    .addComponent(jLabel9)
                    .addComponent(jLabel10)
                    .addComponent(jLabel11)
                    .addComponent(jLabel12)
                    .addComponent(jLabel13))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel2)
                            .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(22, 22, 22)
                        .addComponent(Button_Check)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel5)
                            .addComponent(jScrollPane3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(Button_Next)
                            .addComponent(Button_Previous)))
                    .addComponent(jLabel1))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
    }// </editor-fold>                        
    // Variables declaration - do not modify                     
    private javax.swing.JButton Button_Check;
    private javax.swing.JButton Button_Next;
    private javax.swing.JButton Button_Previous;
    private javax.swing.JTextArea TextArea_Answer;
    private javax.swing.JTextArea TextArea_CorrectAnswer;
    private javax.swing.JTextArea TextArea_Question;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel10;
    private javax.swing.JLabel jLabel11;
    private javax.swing.JLabel jLabel12;
    private javax.swing.JLabel jLabel13;
    private javax.swing.JLabel jLabel14;
    private javax.swing.JLabel jLabel15;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JLabel jLabel7;
    private javax.swing.JLabel jLabel8;
    private javax.swing.JLabel jLabel9;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JScrollPane jScrollPane2;
    private javax.swing.JScrollPane jScrollPane3;
    // End of variables declaration                   
}

Answer 1

Use CardLayout to add multiple JPanel objects to your frame. With CardLayout you will be able to make one panel visible at any time.

Here is a simple demo of CardLayout: https://stackoverflow.com/a/9377623/544983

Answer 2

Try using Component#validate instead

//FileChooser_Open.showOpenDialog(this);
ExaminerPanel newPanel = new ExaminerPanel();
Panel_Main.add(newPanel);
Panel_Main.validate();
Panel_Main.repaint();

Answer 3

What exactly are you trying to achieve with two panels? I copied your code in eclipse, just because it was opened, as they said, the code is long. What I see is a single frame+panel with a menu. I understand that you tied up showing the panel to the "open" menu command, so maybe you need to add a validate to your second panel call if you want to lay it over the first one? Or resort to layouts if you do something trickier.