Jcalender in Swing Java

Question

// I am creating customize jcalender in swing

//I am facing problem regarding dates set //i.e actual month is start from tuesday and it is starting from wednesday // I am finding problem regarding setting values in calender-model

//Above code is running fine but problem in showing actual dates //please suggest me to make necessary changes

import java.awt.Color;


public class Calendar extends JFrame {

    private JPanel contentPane;

     String[] years = { "2008", "2009", "2010" ,"2011","2012","2013","2014"};

      JComboBox comboBox = new JComboBox(years);

      String[] months = { "January", "February", "March", "April", "May", "June", "July", "August",
          "September", "October", "November", "December" };

      JList list = new JList(months);

      JScrollPane scrollPane = new JScrollPane(list);

      CalendarModel model = new CalendarModel();

      JTable table = new JTable(model);

      public Calendar() {
            super();

            getContentPane().setLayout(null);
            comboBox.setBounds(10, 10, 100, 30);
            comboBox.setSelectedIndex(5);
            comboBox.addItemListener(new ComboHandler());
            scrollPane.setBounds(200, 10, 150, 100);
            list.setSelectedIndex(10);
            list.addListSelectionListener(new ListHandler());
            table.setBounds(10, 150, 550, 200);
            model.setMonth(comboBox.getSelectedIndex() + 1998, list.getSelectedIndex());
            getContentPane().add(comboBox);
            getContentPane().add(scrollPane);
            table.setGridColor(Color.black);
            table.setShowGrid(true);
            getContentPane().add(table);

            this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            setSize(530,300);
            setVisible(true);


          }


    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Calendar frame = new Calendar();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public class ComboHandler implements ItemListener {
        public void itemStateChanged(ItemEvent e) {
            System.out.println("ItemState change Method called ");
          model.setMonth(comboBox.getSelectedIndex() + 1998, list.getSelectedIndex());
          table.repaint();
        }
      }

      public class ListHandler implements ListSelectionListener {
        public void valueChanged(ListSelectionEvent e) {
          model.setMonth(comboBox.getSelectedIndex() + 1998, list.getSelectedIndex());
          table.repaint();
        }
      }
    }
    class CalendarModel extends AbstractTableModel {
      String[] days = { "Sun" , "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };

      int[] numDays = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

      String[][] calendar = new String[7][7];

      public CalendarModel() {

          //setting name of days (mon,tues)
        for (int i = 0; i < days.length; ++i)
        {
            System.out.println("day[i] *** "+days[i]);
            calendar[0][i] = days[i];

        }
        for (int i = 1; i < 7; ++i){
          for (int j = 0; j < 7; ++j)
          {
              System.out.println("calendar[i][j] value i ** "+i +" j value "+ j );
            calendar[i][j] = " ";
          }
        }

      }

      public int getRowCount() {
        return 7;
      }

      public int getColumnCount() {
        return 7;
      }

      public Object getValueAt(int row, int column) {
          System.out.println("get Value at ** "+calendar[row][column]); 
        return calendar[row][column];
      }

      /*
      public void setValueAt(Object value, int row, int column) {
          System.out.println("set Value at ** "+(String) value);
        calendar[row][column] = (String) value;
      }*/

      public void setMonth(int year, int month) {
        for (int i = 1; i < 7; ++i)
        {
          for (int j = 0; j < 7; ++j)
          {
            calendar[i][j] = " ";
          }
        }
        java.util.GregorianCalendar cal = new java.util.GregorianCalendar();
        cal.set(year, month, 1);
        int offset = cal.get(java.util.GregorianCalendar.DAY_OF_WEEK) - 1;
        offset += 7;
        int num = daysInMonth(year, month);
        for (int i = 0; i < num; ++i) {
            System.out.println("offset *** "+Integer.toString(i+1));
          calendar[offset / 7][offset % 7] = Integer.toString(i+1);
          ++offset;
        }
      }

      public boolean isLeapYear(int year) {
          System.out.println("Is Leap Year *** ");
        if (year % 4 == 0)
          return true;
        return false;
      }

      public int daysInMonth(int year, int month) {
          System.out.println("day In month*** ");
        int days = numDays[month];
        if (month == 1 && isLeapYear(year))
          ++days;
        System.out.println("days *** "+days);
        return days;
      }

}

Answer 1

I don't know if these are related but...

public void itemStateChanged(ItemEvent e) {

    int index = comboBox.getSelectedIndex();
    System.out.println("index = " + index + "; " + (index + 1998));

    model.setMonth(comboBox.getSelectedIndex() + 1998, list.getSelectedIndex());
    table.repaint();
}

Doesn't produce results which match those that are listed within the combo box. For example, if you select the first value, it will equal 1998, not 2008

So, if I select 2013 from the combo box, I'm actually getting 2003.

When I changed it to

public void itemStateChanged(ItemEvent e) {

    int index = comboBox.getSelectedIndex();
    System.out.println("index = " + index + "; " + (index + 2008));

    model.setMonth(comboBox.getSelectedIndex() + 2008, list.getSelectedIndex());
    table.repaint();
}

It gave me better results.

I also changed

java.util.GregorianCalendar cal = new java.util.GregorianCalendar();

to

java.util.Calendar cal = java.util.Calendar.getInstance();

You should avoid making assumptions about the users calendar system if possible...

I'd also avoid null layouts as well ;)

You should also avoid calling table.repaint when you change the table model, instead try using fireTableDataChanged from within the setMonth method

I would, personally, add the listeners to the combobox and JList before setting there selected indexes, this will allow the listeners to update the model for you...

You'll also need to fix you ListHandler so that it uses 2008 instead 1998

Answer 2

try this.. use - 2 instead of - 1 in offset calculation.

 java.util.GregorianCalendar cal = new java.util.GregorianCalendar();
    cal.set(year, month, 1);
    int offset = cal.get(java.util.GregorianCalendar.DAY_OF_WEEK)- 2 ;
    offset += 7;
    int num = daysInMonth(year, month);
    for (int i = 0; i < num; ++i) {
        System.out.println("offset *** "+Integer.toString(i+1));
      calendar[offset / 7][offset % 7] = Integer.toString(i+1);
      ++offset;

Answer 3

Have a try with this in setMonth method

 public void setMonth(int year, int month) 

Change

 calendar[offset / 7][offset % 7] = Integer.toString(i+1);

To

 calendar[offset / 7][offset % 7] = Integer.toString(i+2);