Generating check boxes dynamically, Netbeans - netbeans

Question

I am developing a desktop application in which I want Admin have option to delete users, for which I planned that whenever Admin clicks on 'delete users' button a new tab will open in which check boxes with the name of all existing users in my database should appear(so that he can delete multiple users simultaneously); so basically I need to generate dynamic check boxes as per my database.
I am using Netbeans 7.0.1, jdk 1.6, sqlite3.
After searching on google I got two links which match to my problem:
http://www.coderanch.com/t/345949/GUI/java/create-dynamic-checkboxes#2805277
Creating dcheckbox dynamically in Java-NetBeans
I have tried to follow the code from above first link but it does not working for me properly. What I does is just created new JFrame in netbeans and called a method inside constructor which create checkboxes as per needed, method's code is as below:
public class Work extends javax.swing.JFrame {
/** Creates new form Work */
public Work() {
initComponents();
checks = new java.util.ArrayList<>();
createCheckboxes();
}
/** 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() {
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
private void createCheckboxes(){
panel = new javax.swing.JPanel();
this.add(panel);
for(int i = 0; i<4; i++){
javax.swing.JCheckBox box = new javax.swing.JCheckBox("check"+i);
panel.add(box);
checks.add(box);
panel.revalidate();
panel.repaint();
}
panel.setVisible(true);
}
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(Work.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Work.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Work.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Work.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 Work().setVisible(true);
}
});
}
// Variables declaration - do not modify
// End of variables declaration
private java.util.ArrayList <javax.swing.JCheckBox> checks;
private javax.swing.JPanel panel;
}
The output is just a blank frame. Please help me to know where I am wrong!!
And yes this code is not connected to database yet, once it will work then I can modify it to work with database.
Also is their any other betterway to accomplish my task or am on right path?`

Answer 1

I think it might help if u call the following function whenever to wanna create a new checkbox..
public class CheckBox extends JFrame{
//private static final long serialVersionUID = 1L;
public CheckBox() {
// set flow layout for the frame
this.getContentPane().setLayout(new FlowLayout(FlowLayout.TRAILING, 50, 20)); //(default) centered alignment and a default 5-unit horizontal and vertical gap.
JCheckBox checkBox1 = new JCheckBox("Checkbox 1");
checkBox1.setSelected(true);
JCheckBox checkBox2 = new JCheckBox("Checkbox 2", true);
JCheckBox checkBox3 = new JCheckBox("Checkbox 3");
// add checkboxes to frame
add(checkBox1);
add(checkBox2);
add(checkBox3);
}
private static void createAndShowGUI() {
//Create and set up the window.
//JFrame frame = new CreateCheckedUncheckedJCheckBox();
CheckBox cb = new CheckBox();
//Display the window.
cb.pack();
cb.setVisible(true);
cb.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
createAndShowGUI();
}
});
}
}

Answer 2

You add the new checkboxes as if your frame was using some simple layout such as FlowLayout, but it is not - it is using GroupLayout - see the generated initComponents() method.
If you want to handle ALL components in the frame dynamically, you can do this (it is better to create an empty class file and then paste the code below; do not ask NB to create a JFrame as it would again create a form to be designed in the visual designer; if you still do it then r-click it and change the layout to something simpler):
public class Work extends javax.swing.JFrame {
private java.util.List <javax.swing.JCheckBox> checks = new java.util.ArrayList<>();;
public Work() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new java.awt.FlowLayout()); // simply put the components next to each other
createCheckboxes();
}
private void createCheckboxes(){
for(int i=0; i<4; i++) {
javax.swing.JCheckBox box = new javax.swing.JCheckBox("check"+i);
add(box);
checks.add(box);
}
pack(); // this will tell the JFrame's panel to layout all the components
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Work().setVisible(true);
}
});
}
}
Or you can design part of your frame with the visual designer and then add the checkboxes. In that case add an empty panel in the designer, set the panel's layout to something like flow or grid layout and then add the checkboxes to that panel from your code in the same way as above.
You validate needs to be called only if the panel/frame is already visible. Calling pack works even then, but might change the size of the frame. Also validating can be done after all components were added not after adding each one.

Answer 3

To add check boxes or any other component dynamically in Netbeans JFrame one need to manage Layout Managers, by default netbeans frames use Free Design Layout, follow steps below:
Create blank JFrame -->Add Jpanel to it-->right click to the panel, select setLayout and change it to GridLayout.
Now we are free to add ant components on this panel.
Also don't forgate to add revalidate() and repaint() methods.
This worked for me.