Java 日期時間函數

1. Java 日期時間函數 DateTime Method

2. 日期時間類別庫 • java.util.* • java.util.Calendar • java.util.GregorianCalendar • java.util.TimeZone • java.util.SimpleTimeZone • java.util.Date • java.text.* • java.text.DateFormat • java.text.SimpleDateFormat • java.text.DateFormatSymbols

3. java.util.Date • 宣告物件 Date today = new Date(); • 方法 • 抓取時getHours() • 抓取分 getMinutes() • 抓取秒 getSeconds()

4. 範例 import java.util.Date; public class TimeExample1{ public static void main(String args[]) { Date nowTime = new Date(); System.out.println(nowTime.getHours()+":“ +nowTime.getMinutes()+":“ +nowTime.getSeconds()); } }

5. java.util.Calendar • Calendar 日曆類別 • 參考網址http://nothing.tw/JDK_API_1_6/java/util/Calendar.html • 宣告物件取得現在的時間 Calendar today = Calendar.getInstance();

6. 範例 import java.util.Calendar; public class CalendarExample1{ public static void main(String args[]) { Calendar today = Calendar.getInstance(); System.out.println("現在時區ERA:"+today.get(Calendar.ERA)); System.out.println("現在年份:"+today.get(Calendar.YEAR)); System.out.println("今天日期:"+today.get(Calendar.DATE)); System.out.println("今天是這個月的幾號:"+today.get(Calendar.DAY_OF_MONTH)); System.out.println("今天是這星期的第幾天:"+today.get(Calendar.DAY_OF_WEEK)); System.out.println("現在幾點:"+today.get(Calendar.HOUR)); } }

7. java.text.DateFormat • DateFormat是日期/時間格式化子類別的抽象類別。(設定日期時間格式用。) • 參考網址 http://nothing.tw/JDK_API_1_6/java/text/DateFormat.html • 方法 • getInstance() • getDateInstance() • getTimeInstance() • getDateTimeInstance() • DateFormat.格式化樣式 • FULL • LONG • MEDIUM • SHORT

8. 範例 import java.text.DateFormat; import java.util.Date; public class DateFormatExample1 { public static void main(String[] args) { Date now = new Date(); System.out.println(" 1. " + now.toString()); System.out.println(" 2. " + DateFormat.getInstance().format(now)); System.out.println(" 3. " + DateFormat.getTimeInstance().format(now)); System.out.println(" 4. " + DateFormat.getDateTimeInstance().format(now)); System.out.println(" 5. " + DateFormat.getTimeInstance(DateFormat.SHORT).format(now)); System.out.println(" 6. " + DateFormat.getTimeInstance(DateFormat.MEDIUM).format(now)); System.out.println(" 7. " + DateFormat.getTimeInstance(DateFormat.LONG).format(now)); //續下頁

9. //承上頁 System.out.println(" 8. " + DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT).format(now)); System.out.println(" 9. " + DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.SHORT).format(now)); System.out.println("10. " + DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG).format(now)); System.out.println("11. " + DateFormat.getDateTimeInstance(DateFormat.FULL, DateFormat.FULL).format(now)); } }

10. SimpleDateFormat import java.text.SimpleDateFormat; import java.util.Date; public class SimpleExample1{ public static void main(String args[]) { Date today = new Date(); SimpleDateFormat f1=new SimpleDateFormat("yyyy/M/d a h:m"); SimpleDateFormat f2=new SimpleDateFormat("yyyy/MMM/d H:m:s"); System.out.println(f1.format(today)); System.out.println(f2.format(today)); } }

11. java.text.SimpleDateFormat

12. java.text.SimpleDateFormat