JAVA基础：万年历 【习题笔记】

 public static void main(String[] args) {System.out.println("请输入年份：");Scanner input = new Scanner(System.in);int year = input.nextInt();System.out.println("请输入月份：");int month = input.nextInt();//计算这个月有多少天int days = 0;if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {days = 31;} else if (month == 4 || month == 6 || month == 9 || month == 11) {days = 30;} else {if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {days = 29;} else {days = 28;}}//2.算输入月份的1号是星期几//2.1先算 你输进来的年份year年 距离 1900年相差的整年天数差int sumYear = 0;for (int i = 1900; i < year; i++) {if (i % 4 == 0 && i % 100 != 0 || i % 400 == 0) {sumYear += 366;} else {sumYear += 365;}}//2.2再算year年的一月 距离month月的天数差int sumMonth = 0;for (int i = 1; i < month; i++) {if (i == 1 || i == 3 || i == 5 || i == 7 || i == 8 || i == 10 || i == 12) {sumMonth += 31;} else if (i == 4 || i == 6 || i == 9 || i == 11) {sumMonth += 30;} else {if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {sumMonth += 29;} else {sumMonth += 28;}}}//2.3计算year年month月1号是星期几？int week = (sumYear + sumMonth + 1) % 7;if (week == 0) {week = 7;}//3.打印日历System.out.println(year + "年" + month + "月");System.out.println("一\t二\t三\t四\t五\t六\t日");for (int i = 1; i < week; i++) {//挤出前面System.out.print("\t");//直接输出}for (int i = 1; i <= days; i++) {//日历内容System.out.print(i + "\t");//直接输出if ((sumMonth + sumYear + i) % 7 == 0) {//换行System.out.println();//输出后换行}}}

最基础的写法，代码量大，但是思路最为清晰，新手必学！！！

 public static void main4(String[] args) {Scanner input = new Scanner(System.in);System.out.println("请输入年份");int year = input.nextInt();System.out.println("请输入月份");int month = input.nextInt();Calendar calendar = Calendar.getInstance();//当前时间calendar.set(Calendar.YEAR, year);calendar.set(Calendar.MONTH, month - 1);//这个月有多少天？int days = calendar.getActualMaximum(Calendar.DATE);//这个月的1号是星期几？calendar.set(Calendar.DATE, 1);int week = calendar.get(Calendar.DAY_OF_WEEK) == 1 ? 7 : calendar.get(Calendar.DAY_OF_WEEK) - 1;//calendar .get(Calendar.DAY_OF_WEEK) :获取1号是本周的第几天//打印日历System.out.println("一\t二\t三\t四\t五\t六\t日\t");for (int i = 1; i < week; i++) {System.out.print("\t");}for (int i = 1; i <= days; i++) {System.out.print(i + "\t");calendar.set(Calendar.DATE, i);if (calendar.get(Calendar.DAY_OF_WEEK) == 1) {System.out.println();}}}

采用日期时间类，使用Canlendar，代码更加简单，更加便捷。