java學習筆記三 2019.6.17 週一 三亞 陰

Date類和Calendar類
一、
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class DateTest1 {

public static void main(String[] args) {
    //Calendar轉化爲Date 
   // Calendar cal=Calendar.getInstance();  
    //Date date=cal.getTime();  

    //Date轉化爲Calendar  日期轉換爲日曆  
    Date now=new Date();
    System.out.println(now.getYear());
    System.out.println(now.getDate());
    System.out.println(now.getHours());
    System.out.println(now.getSeconds());
    System.out.println(now.getClass());

    Calendar cal=Calendar.getInstance();//calendar是抽象類，不能new
    System.out.println(cal.getClass());//java.util.GregorianCalendar

//  GregorianCalendar gc=new GregorianCalendar();
//  gc.setTime(now);
//  System.out.println(gc.get(Calendar.YEAR));

    cal.setTime(now);
    //cal.getTime();

    int year=cal.get(Calendar.YEAR);
    System.out.println(year);
    int month=cal.get(Calendar.MONTH);
    System.out.println(month);
    int week=cal.get(Calendar.DAY_OF_MONTH);
    System.out.println(week);
    int hour=cal.get(Calendar.HOUR);
    System.out.println(hour);
    System.out.println(cal.get(Calendar.DAY_OF_WEEK_IN_MONTH));

    cal.set(2019, 6, 16);
    Date date=cal.getTime();
    System.out.println(date);
    System.out.println(date.getYear());
    System.out.println(date.getMonth());
    System.out.println(date.getDay());

}

}

二、

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class DateTest2 {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Date now=new Date();
    //SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日");//格式要一樣
    String s=sdf.format(now);
    System.out.println(s);

    Date date;
    try {
        date = sdf.parse("2019-06-22 15:33:33");//格式要一樣，不然會拋出異常
        System.out.println(date);
    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}

}