java中獲取當前日期和時間的方法

1. 獲取當期日期、年份、月份

import java.util.Calendar;
public class Main {
  public static void main(String[] args) {
    Calendar now = Calendar.getInstance();
    System.out.println("Current Year is : " + now.get(Calendar.YEAR));
    // month start from 0 to 11
    System.out.println("Current Month is : " + (now.get(Calendar.MONTH) + 1));
    System.out.println("Current Date is : " + now.get(Calendar.DATE));
  }
}

 

2. 獲取前一天、前一個月的日期

Calendar calendar = Calendar.getInstance();//此時打印它獲取的是系統當前時間
calendar.add(Calendar.DATE, -1);    //得到前一天
String  yestedayDate = new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime());
        calendar.add(Calendar.MONTH, -1);    //得到前一個月
        int year = calendar.get(Calendar.YEAR);
       int month = calendar.get(Calendar.MONTH)+1; //輸出前一月的時候要記得加1

 3. 字符串轉爲日期格式

 

String date = "2010-02-01 23:59:59";
SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
try {
Date d = sf.parse(date);
System.out.println(sf.format(d));
} catch (ParseException e) {
e.printStackTrace();
}

 

4.完整的一個例子

 

import   java.util.Date;
import   java.util.Calendar;
import   java.text.SimpleDateFormat;
public   class   TestDate{
public   static   void   main(String[]   args){
Date   now   =   new   Date();
SimpleDateFormat   dateFormat   =   new   SimpleDateFormat("yyyy/MM/dd   HH:mm:ss");//可以方便地修改日期格式
String   hehe   =   dateFormat.format(   now   );
System.out.println(hehe);
Calendar   c   =   Calendar.getInstance();//可以對每個時間域單獨修改
int   year   =   c.get(Calendar.YEAR);
int   month   =   c.get(Calendar.MONTH);
int   date   =   c.get(Calendar.DATE);
int   hour   =   c.get(Calendar.HOUR_OF_DAY);
int   minute   =   c.get(Calendar.MINUTE);
int   second   =   c.get(Calendar.SECOND);
System.out.println(year   +   "/"   +   month   +   "/"   +   date   +   "   "   +hour   +   ":"   +minute   +   ":"   +   second);
}
}