roll[K] = new JCheckBox();
        roll[K].setText(metaData.getColumnLabel(columnIndex));
        roll[K].setBounds(X,Y,150,30);
        Y = Y+30;
        Rectangle r = jPanel3.getBounds();
        int h=r.height;
        if (Y>=h-50){
            Y=0;
            X=X+200;
       }
   jPanel3.add(roll[K]);

roll[K].addItemListener(new ItemListener() {
      public void itemStateChanged(ItemEvent e) {
        System.out.println("Checked? " + roll[K].isSelected());
      }
    });