Adding JCheckBox to JTable using Netbeans - netbeans

Question

I have a JTable in my JDialog which I populate myself in another method. Here is my code and I want the second null in my Object array to be a JCheckBox. I have been scowering the internet and saw someone say I need to override a method in the tablerenderer or something like that and I got confused on how to do it. Anyway here is the code
package privatelessontrackernetbeans;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.TreeMap;
import javax.swing.ImageIcon;
import javax.swing.SwingConstants;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
/**
*
* #author Brent C
*/
public class WeeklyLessonsReductionGUI extends javax.swing.JDialog {
/**
* Creates new form WeeklyLessonsReductionGUI
* #param parent
* #param modal
*/
public WeeklyLessonsReductionGUI(java.awt.Frame parent, boolean modal) {
super(parent, modal);
initComponents();
postInitComponents();
}
private void postInitComponents() {
ImageIcon icon = new ImageIcon(PSLTrackerInfo.file + "ymcaLogo.png");
setIconImage(icon.getImage());
//Table for students that need more lessons
DefaultTableModel dtm = (DefaultTableModel) jTable1.getModel();
dtm.setRowCount(0);
//Center the Titles
DefaultTableCellRenderer centerRenderer = (DefaultTableCellRenderer)
jTable1.getTableHeader().getDefaultRenderer();
centerRenderer.setHorizontalAlignment(SwingConstants.CENTER);
//Center the Cells
jTable1.setDefaultRenderer(Object.class, centerRenderer);
TreeMap<Instructor, ArrayList<Student>> theList =
PSLTrackerInfo.theList_getMap();
for (Instructor key : theList.keySet()) {
ArrayList<Student> students = theList.get(key);
boolean listed = false;
for (Student values : students) {
Calendar c = Calendar.getInstance();
c.set(Calendar.DAY_OF_MONTH, Calendar.MONDAY);
c.set(Calendar.WEEK_OF_YEAR, values.getLastUpdateWeek());
c.set(Calendar.YEAR, values.getLastUpdateYear());
DateFormat df = new SimpleDateFormat("MMMM dd, yyyy");
Date date = c.getTime();
String s = df.format(date);
if (listed) {
Object[] data = new Object[]{null,
values.getName(), s, null, null, null};
dtm.addRow(data);
} else {
Object[] data = new Object[]{values.getInstructor(),
values.getName(), s, null, null, null};
dtm.addRow(data);
listed = true;
}
}
}
}
/**
* 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() {
jScrollPane1 = new javax.swing.JScrollPane();
jTable1 = new javax.swing.JTable();
jButton1 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
setTitle("Lessons Update");
jTable1.setModel(new javax.swing.table.DefaultTableModel(
new Object [][] {
},
new String [] {
"Instructor", "Student", "Last Update", "Lesson Date", "Lesson Complete", "Unscheduled Lessons"
}
) {
boolean[] canEdit = new boolean [] {
false, false, false, false, true, true
};
public boolean isCellEditable(int rowIndex, int columnIndex) {
return canEdit [columnIndex];
}
});
jScrollPane1.setViewportView(jTable1);
jButton1.setText("Update");
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(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 829, Short.MAX_VALUE)
.addContainerGap())
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton1)
.addGap(375, 375, 375))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 275, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jButton1)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
setLocationRelativeTo(null);
}// </editor-fold>
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTable jTable1;
// End of variables declaration
}

Answer 1

No need for a custom renderer, just override the getColumnClass() method of the DefaultTableModel making the column with the boolean a Boolean object.
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;
public class CheckBoxTable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
Object[][] data
= {{"false", false},
{"true", true}};
String[] cols = {"String", "Boolean"};
DefaultTableModel model = new DefaultTableModel(data, cols) {
#Override
public Class<?> getColumnClass(int column) {
if (column == 1) {
return Boolean.class;
} else {
return String.class;
}
}
};
JTable table = new JTable(model);
JOptionPane.showMessageDialog(null, new JScrollPane(table));
}
});
}
}

Answer 2

why you just don't do a "new JCheckBox()" instead of the second null??