package com.sun.lesson02; import java.time.DayOfWeek; import java.time.LocalDate; public class LocalDate01 { public static void main(String[] args) { LocalDate date = LocalDate.now(); int month = date.getMonthValue(); int today = date.getDayOfMonth(); date = date.minusDays(today - 1); DayOfWeek weekday = date.getDayOfWeek(); int value = weekday.getValue(); System.out.println("Mon Tue Wed Thu Fri Sat Sun"); for (int i = 1; i < value; i++) { System.out.print(" "); } while (date.getMonthValue() == month) { System.out.printf("%3d", date.getDayOfMonth()); if(date.getDayOfMonth() == today) { System.out.print("*"); } else { System.out.print(" "); } date = date.plusDays(1); if(date.getDayOfWeek().getValue() == 1) System.out.println(); } if(date.getDayOfWeek().getValue() != 1) System.out.println(); } }
关于minusDays,其内部源码形式如下:
public LocalDate minusDays(long daysToSubtract) { return (daysToSubtract == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-daysToSubtract)); }
如果当天是1号,today-1的输入就是0,然后三目运算会返回1;
如果当天不是1号,那么today就会加上-(today-1),也就是1.