My Jbutton do not take the values of the checkboxes...PLEASE help...

Question

public class  buttonHandler implements ActionListener
        public void actionPerformed(ActionEvent event)
            if(event.getSource()== next)
                pieChart.Chart();
                pieChart.setTitle ("Display Chart");
                pieChart.pack();
                pieChart.show();
                pieChart.setSize(500, 500);
                pieChart.setVisible(true);
            }else if (event.getSource()==graduate && graduate.isSelected())
                      PieChart2D chart2D = new PieChart2D();
                      LegendProperties legendProps = new LegendProperties();
                      String[] legendLabels = {"UnderGraduate", "PostGraduate"};
                      legendProps.setLegendLabelsTexts (legendLabels);
                      numSets = 2;
                      numCats = 1;
                      numItems = 1;
                      Dataset dataset = new Dataset (numSets, numCats, numItems);
                      dataset.set (0, 0, 0, file.uGraduate.length()/13);
                      dataset.set (1, 0, 0, file.pGraduate.length()/12);
                      chart2D.setLegendProperties (legendProps);
                      chart2D.setDataset (dataset);
            } I am trying to get the Jbutton to take the values of the checkbox but i can't make. This is what is have so far. If the values from the check box are in the class the button indicate to the piechart is diplayed. I have registered some more checkboxes after this code still with no values inside. I am using some not java classes to display the piechart. The dataset is a class in this package which stores the values for the pie chart. The error i am getting has as follows.
Validating PieChart2D
Validating Chart2D
Validating Object2D
Validating Object2DProperties
Object2DProperties was valid
Object2D was valid
Validating Chart2DProperties
Chart2DProperties was valid
LegendProperties is null
Chart2D was invalid
Validating PieChart2DProperties
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
PieChart2DProperties was valid
        at net.sourceforge.chart2d.Chart2D.updateChart2D(Chart2D.java:152)
Dataset is null
        at net.sourceforge.chart2d.PieChart2D.getPreferredSize(PieChart2D.java:200)
Validating MultiColorsProperties
        at java.awt.FlowLayout.preferredLayoutSize(FlowLayout.java:368)
MultiColorsProperties was valid
        at java.awt.Container.preferredSize(Container.java:1558)
Possibly unable to check for all invalidities because of early invalidity
        at java.awt.Container.getPreferredSize(Container.java:1543)
PieChart2D was invalidEverything that is valid is in the class the button points to the other and the invalid in the ones i am trying to enter.
Could someone please show me how to do it...? I need to get the values from the checkbox to the button...well that is what i think...
I post the same thing the event handling forum but i didnt get any replay and i thought of trying this one as well...

Answer 1

Post a small demo code that is generally compilable, runnable and could reproduce your problem. See: http://homepage1.nifty.com/algafield/sscce.html.