Java开发网 - 关于GregorianCalendar类的DAY_OF

Topic: 关于GregorianCalendar类的DAY_OF_MONTH问题

1.关于GregorianCalendar类的DAY_OF_MONTH问题

Posted by: szaba
Posted on: 2005-07-08 15:13

我是菜鸟最近刚开始看 CORE JAVA这本书
其中有一段关于GregorianCalendar类的例程我稍微改了一下以对其方法和属性有进一步了解
代码如下：
文件名：gCalendar.java
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
import java.util.*;

public class gCalendar
{
public static void main(String[] args)
{
GregorianCalendar g_now = new GregorianCalendar(2005,6,1);
Date d_now = g_now.getTime();
System.out.println(g_now);
System.out.println(d_now);
System.out.println("DAY_OF_MONTH = ["+g_now.DAY_OF_MONTH+"]");
}
}
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
输出结果如下：
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
java.util.GregorianCalendar[time=1120147200000,areFieldsSet=false,areAllFieldsSe
t=false,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Shanghai",offset=2
8800000,dstSavings=0,useDaylight=false,transitions=19,lastRule=null],firstDayOfW
eek=1,minimalDaysInFirstWeek=1,ERA=?,YEAR=2005,MONTH=6,WEEK_OF_YEAR=?,WEEK_OF_MO
NTH=?,DAY_OF_MONTH=1,DAY_OF_YEAR=?,DAY_OF_WEEK=?,DAY_OF_WEEK_IN_MONTH=?,AM_PM=?,
HOUR=?,HOUR_OF_DAY=?,MINUTE=?,SECOND=?,MILLISECOND=?,ZONE_OFFSET=?,DST_OFFSET=?]

Fri Jul 01 00:00:00 CST 2005
DAY_OF_MONTH = [5]
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
问题是日期设为2005年7月1日，为什么DAY_OF_MONTH的值是5呢？从直接输出的GregorianCalendar数据看其中的DAY_OF_MONTH明明是1呀？

2.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]	Copy to clipboard
Posted by: maple Posted on: 2005-07-08 17:31 DAY_OF_MONTH是GregorianCalendar这个类中的一个public static的一个常量，是取得DAY_OF_MONTH这个值的ID，想要取得这个值需要g_now.get(GregorianCalendar.DAY_OF_MONTH)这么来获得。

3.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]	Copy to clipboard
Posted by: szaba Posted on: 2005-07-08 21:02 YES！谢谢楼上的兄弟！

4.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]	Copy to clipboard
Posted by: szaba Posted on: 2005-07-08 21:03 那象我这样的写法取出来的是什么东东呢？

5.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]	Copy to clipboard
Posted by: why Posted on: 2005-07-08 23:15 szaba wrote: 那象我这样的写法取出来的是什么东东呢？ g_now.toString() d_now.toString()

6.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: why]	Copy to clipboard
Posted by: szaba Posted on: 2005-07-09 06:58 老大不好意思我还是不明白能说详细一点吗？

7.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]

Copy to clipboard

Posted by: why
Posted on: 2005-07-09 07:55

szaba wrote:
老大不好意思我还是不明白
能说详细一点吗？

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/System.html
out
public static final PrintStream outThe "standard" output stream. This stream is already open and ready to accept output data. Typically this stream corresponds to display output or another output destination specified by the host environment or user.

For simple stand-alone Java applications, a typical way to write a line of output data is:

System.out.println(data)

See the println methods in class PrintStream.

http://java.sun.com/j2se/1.4.2/docs/api/java/io/PrintStream.html#print(java.lang.Object)
public void print(Object obj)
Print an object. The string produced by the String.valueOf(Object) method is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
obj - The Object to be printed

See Also:
Object.toString()

8.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: why]

Copy to clipboard

Posted by: szaba
Posted on: 2005-07-09 22:29

why wrote:
g_now.toString()
d_now.toString()

可是如果我把您说的g_now.toString()直接用println输出的话内容是下面这样子
DAY_of_MONTH = [java.util.GregorianCalendar[time=1120919176762,areFieldsSet=true
,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Shan
ghai",offset=28800000,dstSavings=0,useDaylight=false,transitions=19,lastRule=nul
l],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2005,MONTH=6,WEEK_OF_YEA
R=28,WEEK_OF_MONTH=2,DAY_OF_MONTH=9,DAY_OF_YEAR=190,DAY_OF_WEEK=7,DAY_OF_WEEK_IN
_MONTH=2,AM_PM=1,HOUR=10,HOUR_OF_DAY=22,MINUTE=26,SECOND=16,MILLISECOND=762,ZONE
_OFFSET=28800000,DST_OFFSET=0]]
这个结果和我原来写的大相径庭啊
原来的是这样的
DAY_of_MONTH = [5]
DAY_of_YEAR = [6]
这个 5 和6具体是怎么出来的呢？
请WHY老大继续赐教！谢谢！

9.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]

Copy to clipboard

Posted by: why
Posted on: 2005-07-10 00:48

szaba wrote:
可是如果我把您说的g_now.toString()直接用println输出的话内容是下面这样子
...
这个结果和我原来写的大相径庭啊
原来的是这样的
DAY_of_MONTH = [5]
DAY_of_YEAR = [6]
这个 5 和6具体是怎么出来的呢？
请WHY老大继续赐教！谢谢！

I don't know what you've done and how you got the above result.

You should not access g_now.DAY_OF_MONTH and g_now.DAY_OF_YEAR, which are static constants (field numbers) defined for java.util.Calendar
http://java.sun.com/j2se/1.4.2/docs/api/constant-values.html#java.util.Calendar.DAY_OF_MONTH
http://java.sun.com/j2se/1.4.2/docs/api/constant-values.html#java.util.Calendar.DAY_OF_YEAR
public static final int DAY_OF_MONTH 5
public static final int DAY_OF_WEEK 7
public static final int DAY_OF_WEEK_IN_MONTH 8
public static final int DAY_OF_YEAR 6

10.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]	Copy to clipboard
Posted by: bluepure Posted on: 2005-07-10 10:07 源代码定义的全局静态不可变变量就是 public final static int DAY_OF_MONTH = 5; 你真要问为什么，就去找sun吧。真正的取时间值是调用get方法： g_now.get(g_now.DAY_OF_MONTH) System.out.println("DAY_OF_MONTH = [" + g_now.get(g_now.DAY_OF_MONTH) + "]"); 这个才是取得域为 DAY_OF_MONTH 的值。

11.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]	Copy to clipboard
Posted by: szaba Posted on: 2005-07-10 11:08 呵呵楼上两位老大多谢了！我是菜鸟还没敢想去看DOC “源代码定义的全局静态不可变变量就是” 明白了！再次感谢各位！！！

12.Re:关于GregorianCalendar类的DAY_OF_MONTH问题 [Re: szaba]	Copy to clipboard
Posted by: szaba Posted on: 2005-07-11 15:11 了解了既然是常量那么记住了以后只要这样写结果也是一样的 g_now.get(5) 跟 g_now.get(GregorianCalendar.DAY_OF_MONTH) 是一样的