Calculate leap year in Java [duplicate]

Answer 1

you could use a switch statment, with a few if statements inside the february case:

switch(month)
{
case 1:
    System.out.println("January " + year + " has 31 days");
    break;
case 2:
    int n=28;
    if(year%4==0 && (year%100!=0 || year%400==0)
        n++;
    System.out.println("February " + year + " has "+n+" days");
    break;
case 3:
    System.out.println("March " + year + " has 31 days");
    break;
case 4:
    System.out.println("April " + year + " has 30 days");
    break;
case 5:
    System.out.println("May " + year + " has 31 days");
    break;
case 6:
    System.out.println("June " + year + " has 30 days");
    break;
case 7:
    System.out.println("July " + year + " has 31 days");
    break;
case 8:
    System.out.println("August " + year + " has 31 days");
    break;
case 9:
    System.out.println("September " + year + " has 30 days");
    break;
case 10:
    System.out.println("October " + year + " has 30 days");
    break;
case 11:
    System.out.println("November " + year + " has 30 days");
    break;
case 12:
    System.out.println("December " + year + " has 31 days");
    break;
default case:
    System.out.println("Please enter the numerical value of the month you would like to view");
}

see http://download.oracle.com/javase/tutorial/java/nutsandbolts/switch.html for more info

Answer 2

If you use the GregorianCalendar, you could do as below

Determines if the given year is a leap year. Returns true if the given year is a leap year. To specify BC year numbers, 1 - year number must be given. For example, year BC 4 is specified as -3.

GregorianCalendar cal = new GregorianCalendar();

if(cal.isLeapYear(year))
{
    System.out.print("Given year is leap year.");
}
else
{ 
    System.out.print("Given year is not leap year.");
}

Answer 3

Quoting http://en.wikipedia.org/wiki/Leap_year

Years that are evenly divisible by 100 are not leap years, unless they are also evenly divisible by 400, in which case they are leap years.

So if you want to reinvent the wheel:

boolean isLeapYear = year%4 == 0 && (year%100 != 0 || year%400 == 0)

But the most elegant solution (taken from here) is probably

public static boolean isLeapYear(int year) {
  Calendar cal = Calendar.getInstance();
  cal.set(Calendar.YEAR, year);
  return cal.getActualMaximum(DAY_OF_YEAR) > 365;
}