月光宝盒之时间魔法--java时间的前生今世
月光宝盒花絮
“曾经有一份真诚的爱情摆在我的面前，但是我没有珍惜，等到了失去的时候才后悔莫及，尘世间最痛苦的事莫过于此。如果可以给我一个机会再来一次的话，我会跟那个女孩子说我爱她，如果非要把这份爱加上一个期限，我希望是一万年！”---大话西游之仙履奇缘
public static void main(String[] args) { Date date=new Date(2018,12,31,0,0,0); System.out.println(date.getYear()); System.out.println(date.getMonth()); System.out.println(date.getDay()); }
我们想打印出的结果是
2018
12
31
可是，运行后的结果打印
2019
0
5
穿越了吗？还是我的机器有问题？
换了别的机器依然如此。代码是不会骗人的，只好进源码看看
/** * Allocates a <code>Date</code> object and initializes it so that * it represents the instant at the start of the minute specified by * the <code>year</code>, <code>month</code>, <code>date</code>, * <code>hrs</code>, and <code>min</code> arguments, in the local * time zone. * * @param year the year minus 1900. * @param month the month between 0-11. * @param date the day of the month between 1-31. * @param hrs the hours between 0-23. * @param min the minutes between 0-59. * @see java.util.Calendar * @deprecated As of JDK version 1.1, * replaced by <code>Calendar.set(year + 1900, month, date, * hrs, min)</code> or <code>GregorianCalendar(year + 1900, * month, date, hrs, min)</code>. */ @Deprecated public Date(int year, int month, int date, int hrs, int min) { this(year, month, date, hrs, min, 0); }
程序大揭秘
- 设置年份是从1900开始的，即2018-1900=118
- 设置月份是从0开始的，即0~11，12等于下一年119年的第一个月即值为0
- day返回的是是周几
/** * Returns the day of the week represented by this date. The * returned value (<tt>0</tt> = Sunday, <tt>1</tt> = Monday, * <tt>2</tt> = Tuesday, <tt>3</tt> = Wednesday, <tt>4</tt> = * Thursday, <tt>5</tt> = Friday, <tt>6</tt> = Saturday) * represents the day of the week that contains or begins with * the instant in time represented by this <tt>Date</tt> object, * as interpreted in the local time zone. * * @return the day of the week represented by this date. * @see java.util.Calendar * @deprecated As of JDK version 1.1, * replaced by <code>Calendar.get(Calendar.DAY_OF_WEEK)</code>. */ @Deprecated public int getDay() { return normalize().getDayOfWeek() - BaseCalendar.SUNDAY; }
java时间前生之Calenar
在1.1 版中，Calendar 类被添加到了Java 平台中，以矫正Date的缺点，由此大部分的Date 方法就都被弃用了。遗憾的是，这么做只能使情况更糟。我们的程序说明Date 和Calendar API 有许多问题。
public static void