Here you can find the source of daysOfMonth(int year, int month)
public static int daysOfMonth(int year, int month)
//package com.java2s; //License from project: Open Source License public class Main { public static int daysOfMonth(int year, int month) { int days = 0; switch (month) { case 1:/* w w w . j a v a 2s. c o m*/ case 3: case 5: case 7: case 8: case 10: case 12: days = 31; break; case 4: case 6: case 9: case 11: days = 30; break; case 2: if (year % 4 == 0) { days = 29; } else { days = 28; } } return days; } }