String、Date、Calendar之间的转换

1.String、Date、Calendar之间的转换

　　要用到格式化类SimpleDateFormat

 package com.rong.se;

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

 public class StringDate {

     public static void main(String[] args) {
         // 格式化对象
         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
         // SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
         // /////////////////////////////////////////////////////
         // SimpleDateFormat sdf=new SimpleDateFormat();
         // sdf.applyPattern("yyyy-MM-dd hh:mm:ss");

         try {
             // String类型转换为Date类型
             String string = "2017-11-11 20:20:20";
             Date date = sdf.parse(string);
             System.out.println(date);

         } catch (ParseException e) {
             e.printStackTrace();
         }

         // Date类型转换为String类型
         Date date = new Date();
         String format = sdf.format(date);
         System.out.println(format);

         // Calendar类型转换为Date类型
         Calendar calendar = Calendar.getInstance();
         Date cDate = calendar.getTime();
         System.out.println(cDate);

         // Date类型转换为Calendar类型
         try {
             String string = "1995-09-24 13:14:03";
             Date parse = sdf.parse(string);
             // ///////////////////////////////////
             calendar.setTime(parse);
             // 获取年份
             System.out.println(calendar.get(Calendar.YEAR));

         } catch (ParseException e) {
             e.printStackTrace();
         }
         // String类型转换为Calendar类型
         try {
             String str = "2002-01-01 18:30:00";
             Date parse = sdf.parse(str);
             Calendar instance = Calendar.getInstance();
             instance.setTime(parse);
             System.out.println(instance.get(Calendar.YEAR));
         } catch (ParseException e) {
             e.printStackTrace();
         }
         // Calendar类型转换为String类型
         Calendar instance = Calendar.getInstance();
         Date time = instance.getTime();
         String string = sdf.format(time);
         System.out.println(string);

     }

 }