Passing JAVA objects to different methods

Question

As you can see that
"public static IntervalCategoryDataset createDataset()" want to get the data and attributes from storeStartDate and storeEndDate methods. i have class files, StartDate and EndDate that contains all the accessor methods. after i have store the relevant attributes, i want to call it out in the "public static IntervalCategoryDataset createDataset()" method to manipulate it.
i hope that my question doesn't confuse you all. hope that you all can guide me on this. Thank you
package ericTest;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.text.ParseException;
import java.util.StringTokenizer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Calendar;
import java.util.Date;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.data.category.IntervalCategoryDataset;
import org.jfree.data.gantt.Task;
import org.jfree.data.gantt.TaskSeries;
import org.jfree.data.gantt.TaskSeriesCollection;
import org.jfree.data.time.SimpleTimePeriod;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;
import Gantt.Chart;
import com.db4o.Db4o;
import com.db4o.ObjectContainer;
import com.db4o.ObjectSet;
public class GanttDemo3 extends ApplicationFrame {
     private static ObjectContainer db;
     private static String day;
     private static String month;
     private static String year;
     private static String task;
     private static String startDate;
     private static String endDate;
     private static String startDay;
     private static String startMonth;
     private static String startYear;
     public static int startDay1;
     public static int startMonth1;
     public static int startYear1;
     public static int startDay2;
     public static int startMonth2;
     public static int startYear2;
     public static String endDay;
     public static String endMonth;
     public static String endYear;
     public static int endDay1;
     public static int endMonth1;
     public static int endYear1;
     public static int endDay2;
     public static int endMonth2;
     public static int endYear2;
     DataInputStream dis = null;
     String fileRecord = null;
   public GanttDemo3(final String title) {
        super(title);
        final IntervalCategoryDataset dataset = createDataset();
        final JFreeChart chart = createChart(dataset);
        // add the chart to a panel...
        final ChartPanel chartPanel = new ChartPanel(chart);
        chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));
        setContentPane(chartPanel);
         public final static String filename = "C:\\KLGCC Mock Up.yap";
         public void storeData() throws IOException{
              new File(filename).delete();
              db = Db4o.openFile(filename);
                   File f = new File("C:\\KLGCC Mock Up.txt");
                   FileReader fis = new FileReader(f);
                   BufferedReader bis = new BufferedReader(fis);
                   while((fileRecord = bis.readLine()) != null){
                             StringTokenizer st = new StringTokenizer(fileRecord,",");
                             task = st.nextToken();
                             startDate = st.nextToken();
                             endDate = st.nextToken();
                             Country c = new Country(task, startDate, endDate);
                             db.set(c);               
                   db.close();
         public void storeStartDate() throws ParseException{
              db = Db4o.openFile(filename);
              Country c = new Country();
              ObjectSet result = db.get(c);
              while(result.hasNext()){
                   Country obj = (Country)result.next();
                   String sDate = obj.getStartDate();
                   StringTokenizer str = new StringTokenizer(sDate, "/");
                   startMonth = str.nextToken();
                   startDay = str.nextToken();
                   startYear = str.nextToken();
                   int startMonth1 = Integer.parseInt(startMonth);
                   int startDay1 = Integer.parseInt(startDay);
                   int startYear1 = Integer.parseInt(startYear);
                   StartDate sd = new StartDate(startDay1, startMonth1, startYear1);
                   ArrayList<Integer> startDay2 = new ArrayList<Integer>();
                   startDay2.add(startDay1);
                   ArrayList<Integer> startMonth2 = new ArrayList<Integer>();
                   startMonth2.add(startMonth1);
                   ArrayList<Integer> startYear2 = new ArrayList<Integer>();
                   startYear2.add(startYear1);                 
              db.close();          
    public void storeEndDate() throws ParseException{
              db = Db4o.openFile(filename);
              Country c = new Country();
              ObjectSet result = db.get(c);
              while(result.hasNext()){
                   Country obj = (Country)result.next();
                   String sEndDate = obj.getEndDate();
                   StringTokenizer str1 = new StringTokenizer(sEndDate, "/");
                   endMonth = str1.nextToken();
                   endDay = str1.nextToken();
                   endYear = str1.nextToken();
                   int endMonth1 = Integer.parseInt(endMonth);
                   int endDay1 = Integer.parseInt(endDay);
                   int endYear1 = Integer.parseInt(endYear);
                   EndDate ed = new EndDate(endDay1, endMonth1, endYear1);
                   ArrayList<Integer> endDay2 = new ArrayList<Integer>();
                   endDay2.add(startDay1);
                   ArrayList<Integer> endMonth2 = new ArrayList<Integer>();
                   endMonth2.add(endMonth1);
                   ArrayList<Integer> endYear2 = new ArrayList<Integer>();
                   endYear2.add(endYear1);
              db.close();
public static IntervalCategoryDataset createDataset() {
         final TaskSeries s1 = new TaskSeries("Scheduled");
         StartDate sd = new StartDate(startDay1, startMonth1, startYear1);
         EndDate ed = new EndDate(endDay1, endMonth1, endYear1);
        s1.add(new Task(task,
               new SimpleTimePeriod(date(sd.getStartDay1(),sd.getStartDay1(), sd.getStartYear1()),
                                    date(ed.getEndDay1(), ed.getEndMonth1(), ed.getendYear1()))));
        System.out.println("dumb");
                final TaskSeriesCollection collection = new TaskSeriesCollection();
        collection.add(s1);
        return collection;
     * Utility method for creating <code>Date</code> objects.
     * @param day  the date.
     * @param month  the month.
     * @param year  the year.
     * @return a date.
    private static Date date(final int startDay2, final int startMonth2, final int startYear2) {
        System.out.println("sdojsodj");
         final Calendar calendar = Calendar.getInstance();
        calendar.set(startYear2, startMonth2, startDay2);
        final Date result = calendar.getTime();
        return result;
     * Creates a chart.
     * @param dataset  the dataset.
     * @return The chart.
    private JFreeChart createChart(final IntervalCategoryDataset dataset) {
        final JFreeChart chart = ChartFactory.createGanttChart(
            "Gantt Chart Demo",  // chart title
            "Task",              // domain axis label
            "Date",              // range axis label
            dataset,             // data
            true,                // include legend
            true,                // tooltips
            false                // urls
//        chart.getCategoryPlot().getDomainAxis().setMaxCategoryLabelWidthRatio(10.0f);
        return chart;   
    public static void main(final String[] args) throws IOException, ParseException
        final GanttDemo3 demo = new GanttDemo3("Gantt Chart Demo 1");
        demo.storeData();
        demo.storeStartDate();
        //demo.storeEndDate();
        //demo.pack();
        //RefineryUtilities.centerFrameOnScreen(demo);
        //demo.setVisible(true);
}

Answer 1

the error that came out in eclipse is
Exception in thread "main" java.lang.IllegalArgumentException: Null 'description' argument.
     at org.jfree.data.gantt.Task.<init>(Task.java:87)
     at ericTest.GanttDemo3.createDataset(GanttDemo3.java:191)
     at ericTest.GanttDemo3.<init>(GanttDemo3.java:78)
     at ericTest.GanttDemo3.main(GanttDemo3.java:248)and if i replace this
public static IntervalCategoryDataset createDataset() {
         final TaskSeries s1 = new TaskSeries("Scheduled");
         StartDate sd = new StartDate(startDay1, startMonth1, startYear1);
         EndDate ed = new EndDate(endDay1, endMonth1, endYear1);
        s1.add(new Task(task,
               new SimpleTimePeriod(date(sd.getStartDay1(),sd.getStartDay1(), sd.getStartYear1()),
                                    date(ed.getEndDay1(), ed.getEndMonth1(), ed.getendYear1()))));
        System.out.println("dumb");
                final TaskSeriesCollection collection = new TaskSeriesCollection();
        collection.add(s1);
        return collection;
    }with
public static IntervalCategoryDataset createDataset() {
         final TaskSeries s1 = new TaskSeries("Scheduled");
         Chart chart = new Chart();
        s1.add(new Task(chart.getTitle(),
               new SimpleTimePeriod(date(chart.getStartDay(), chart.getStartMonth(), chart.getStartYear()),
                                    date(chart.getEndDay(), chart.getEndMonth(), chart.getEndYear()))));
System.out.println("dumb");
                final TaskSeriesCollection collection = new TaskSeriesCollection();
        collection.add(s1);
        return collection;
    }the chart class file has all the accessor methods and all the values is hard code. so the graph can be generated. the problem now is if i want to get the values from the StartDate and EndDate methods to get the dates so that i can put it into the createDataset method to add the values needed for the graph.
can anyone help me on this? thanks alot