java获取当前日期的前一天日期与字符串日期之间的转换

 Java中的日期处理一般用util包中的Calendar类，再用Calendar的getTime()方法生成对应的Date，最后用SimpleDateFormat输出

 

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;


public class test1 {

    public static void main(String[] args) {

        //获取当期日期、年份、月份
        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));

        //得到前一天的日期并将所得到的日期以“yyyy-mm-dd”的格式进行输出
        Calendar calendar = Calendar.getInstance();//此时打印它获取的是系统当前时间
        calendar.add(Calendar.DATE, -1);    //获得前一天
        String  yestedayDate= new SimpleDateFormat("yyyy-MM-dd").format(calendar.getTime());
        System.out.println("yestedayDate is："+yestedayDate);
        //前一个月的日期
        calendar.add(Calendar.MONTH, -1);    //获得前一个月
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH)+1; //输出前一月的时候要记得加1

        //字符串转为日期格式
        String date = "2013-01-01 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();
        }
      }
}