java代码实现月份-1的简单介绍

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这个Java程序，month为什么要减1呢？

因为JDK的月份表示范围是0~11，分别表示1月至12月。

而用户习惯表示的月份往往是从1开始至12之间。

为了将用户习惯的月份表示法转换到JDK固定的表示法，故将用户表示的月份数减1，以得到JDK表示的月份数。

相关问答

Q1: 用java实现日期类的加减

import java.util.Date;

import java.util.Calendar;

import java.text.SimpleDateFormat;

import java.util.*;

public class CalendarExample {

private static void CalendarTimemethod() {

Date date = Calendar.getInstance().getTime();

System.out.println("Current date and time is: " + date);

System.out.println();

}

private static void SimpleDateFormatmethod() {

Calendar date = Calendar.getInstance();

SimpleDateFormat dateformatter = new SimpleDateFormat(

"E yyyy.MM.dd 'at' hh:mm:ss a zzz");

System.out.println("Current date and time in simple date format: "

+ dateformatter.format(date.getTime()));

System.out.println();

}

private static void Adddates() {

System.out.println("Performing operations on calendar dates.");

// Get today's date

Calendar date = Calendar.getInstance();

Calendar cldr;

SimpleDateFormat dateformatter = new SimpleDateFormat(

"E yyyy.MM.dd 'at' hh:mm:ss a zzz");

cldr = (Calendar) date.clone();

cldr.add(Calendar.DAY_OF_YEAR, -(365 * 2));

System.out.println("Before two years it was: "

+ dateformatter.format(cldr.getTime()));

cldr = (Calendar) date.clone();

cldr.add(Calendar.DAY_OF_YEAR, +5);

System.out.println("After five years it will be: "

+ dateformatter.format(cldr.getTime()));

System.out.println();

}

private static void DateDifference() {

System.out.println("Difference between two dates");

Date startDate1 = new GregorianCalendar(2005, 02,

25, 14, 00).getTime();

Date endDate1 = new Date();

;

long diff = endDate1.getTime() - startDate1.getTime();

System.out.println(" Difference between " + endDate1);

System.out.println(" and " + startDate1 + " is " + (diff /

(1000L * 60L * 60L * 24L)) + " days.");

System.out.println();

}

private static void Getcalendermethods() {

System.out.println("Various get methods of the calendar class:");

Calendar calender = Calendar.getInstance();

System.out.println("Year : "

+ calender.get(Calendar.YEAR));

System.out.println("Month : "

+ calender.get(Calendar.MONTH));

System.out.println("Day of Month : "

+ calender.get(Calendar.DAY_OF_MONTH));

System.out.println("Day of Week : "

+ calender.get(Calendar.DAY_OF_WEEK));

System.out.println("Day of Year : "

+ calender.get(Calendar.DAY_OF_YEAR));

System.out.println("Week of Year : "

+ calender.get(Calendar.WEEK_OF_YEAR));

System.out.println("Week of Month : "

+ calender.get(Calendar.WEEK_OF_MONTH));

System.out.println("Day of the Week in Month : "

+ calender.get(Calendar.DAY_OF_WEEK_IN_MONTH));

System.out.println("Hour : " + calender.get(Calendar.HOUR));

System.out.println("AM PM : " + calender.get(Calendar.AM_PM));

System.out.println("Hour of the Day : "

+ calender.get(Calendar.HOUR_OF_DAY));

System.out.println("Minute : " + calender.get(Calendar.MINUTE));

System.out.println("Second : " + calender.get(Calendar.SECOND));

System.out.println();

}

public static void main(String[] args) {

System.out.println();

CalendarTimemethod();

SimpleDateFormatmethod();

Adddates();

DateDifference();

Getcalendermethods();

}

以上答案有林氏120烫伤中心提供。稍微再修改下就可以

Q2: Java Date类型减一个月怎么做

String startDateStr = "";

String endDateStr = "";

TimeZone tzES2 = TimeZone.getTimeZone("GMT+8");

Calendar calES2 = Calendar.getInstance(tzES2);

Calendar ca = Calendar.getInstance();

Date now = ca.getTime();

DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd");

dateFormat.setCalendar(calES2);

ca.set(Calendar.DATE, ca.getActualMinimum(Calendar.DAY_OF_MONTH));//设置当前日期为当前月的第一天

now = ca.getTime();

startDateStr = dateFormat.format(now);

ca.set(Calendar.DATE, ca.getActualMaximum(Calendar.DAY_OF_MONTH));//设置当前日期为当前月的最后一天

now = ca.getTime();

endDateStr = dateFormat.format(now);

System.out.println(startDateStr);

System.out.println(endDateStr);

ca.add(Calendar.MONTH, -1);//设置日期为当前日期加上-1个月(即减去1个月)的日期。

后面的操作同上！

Q3: JAVA中怎么实现，根据用户输入的年份和月份得到当月第1天（该月1号）

抽了点时间写了些代码：给你看看是不是你想要的，你是初学者把，俺给你加些注释 package yjh.action; import java.text.SimpleDateFormat; //定制日期格式的类 import java.util.Calendar; //日历类 import java.util.Date; //当前日期和时间的Data类 import java.util.Scanner;//读取用户输入的类 public class DataCounter{ public int getDay(String strDate) throws Exception { int day = 0; //设定一个特定的日期格式，例如2009-01-03 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); //把用户输入的字符串转化为日期和时间的格式 Date date = format.parse(strDate); //返回系统的当前状态时间 Calendar cal = Calendar.getInstance(); //用给定的 date 设置此 cal cal.setTime(date); //返回年月日中的天数 day = cal.get(cal.DAY_OF_YEAR); return day; } public static void main(String args[]) { try { System.out.println("请输入日期，格式如:2009-03-25:"); //读取用户的输入 Scanner scan = new Scanner(System.in); String str = scan.next(); int day; day = new DataCounter().getDay(str); System.out.println(str + "是" + str.subSequence(0, 4) + "年的第" + day + "天"); } catch (Exception e) { // TODO 自动生成 catch 块 e.printStackTrace(); } } }

Q4: 如何用java编程实现“产生一个1-12的数，并根据随机数的值输出对应月份的名称”？

public String getMonthName() {

int month = (int) (Math.random() * 12 + 1);

switch (month) {

case 1:

return "一月";

case 2:

return "二月";

case 3:

return "三月";

case 4:

return "四月";