/*
	Counting Days from the start of the year
	
	Given today's date, tell us which days of the year today is.
	For example, Jan 1 is the first day of the year
	December 31 is the 365th day of the year (if the year is not a leap year), etc.
*/

import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;

public class CountingDays extends Applet implements AdjustmentListener
       {
   int day, month, year;
   int dayNumber;
   
   Scrollbar dayBar, monthBar;
   Label dayLabel, monthLabel;
   
   public void init() {
   
      // initialize the variables to today's date
      day = 6;
      month = 10;
      year = 2003;
      // Later we will see how to get this either form the user
      // or from within the computer itself
   
      // Create GUI
      // dayBar will be used to adjust the day (goes from 1..31)
      dayLabel = new Label("Day:");
      add(dayLabel);
      dayBar = new Scrollbar(Scrollbar.HORIZONTAL, day, 1, 1, 32);
      add(dayBar);
      dayBar.addAdjustmentListener(this);
   
   
      // monthbar will be used to adjust the month (goes from 1..12)
      monthLabel = new Label("Month:");
      add(monthLabel);
      monthBar = new Scrollbar(Scrollbar.HORIZONTAL, month, 1, 1, 13);
      add(monthBar);
      monthBar.addAdjustmentListener(this);
   
      // count the days
      dayNumber = countDays(day, month, year);
   
   } // init
   
   public void paint(Graphics g) {
      // print the value of date and day number
      g.drawString("The date is "+month+"/"+day+"/"+year,   20, 100);
      g.drawString("It is the "+dayNumber+"th day of the year.",   20, 120);
   } // paint
   
   public void adjustmentValueChanged(AdjustmentEvent e) {
   
      // some srollbar was adjusted, get new values for both
      int d, m;
   
      d = dayBar.getValue();
      m = monthBar.getValue();
   
      // make sure the d is a valid date in the month, m
      if (d <= daysInMonth(m, year)) {
   
         day = d;
         month = m;
   
         // compute the number of days
         dayNumber = countDays(day, month, year);
   
         // redraw the result
         repaint();
      }
   } // adjustmentValueChanged
   
   private int countDays(int d, int m, int y) {
   
      int result = 0;
   
      // Start from Jan, and go all the way to m-1 and count
      // all the days in full months from Jan to m-1
      for (int mo = 1; mo < m; mo++)
      result = result + daysInMonth(mo, y);
   
      // Add days in current month
      result = result + d;
    
      return result;
   } // countDays
   
   private int daysInMonth(int m, int y) {
      // return the number of days in the month m, in year y
      switch (m) {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12: return 31;
        case 4:
        case 6:
        case 9:
        case 11: return 30;
        case 2: if (leapYear(y))
                  return 29;
                else
                  return 28;
       } // switch
       return 0;	// This is needed. If it gets here, m was not a valid #
   } // daysInMonth
   
   private boolean leapYear(int y) {
      // returns true is y is a leap year
      return ((y % 4 == 0 && y%100 != 0) || (y%400 == 0));
   } // leapYear
   
   
}// CountingDays
     

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