DateFormat 和 SimpleDateFormat

DateFormat是一個格式化和解析日期或時間的抽象類. 它的子類, 如SimpleDateFormat, 允許進行格式化(即date -> text), 分析(text -> date), 規範化. 該日期以Date對象表示, 或自1970年1月1日, 格林尼治標準時間(GMT)00:00:00起以毫秒表示.

SimpleDateFormat是一個用於本土(locale-sensitive)格式化和解析日期方式的具體類.

時間格式語法
要指定的時間格式, 使用時間模式字符串. 在這個模式中, 所有的ASCII字母被保留為模式字母, 其中定義如下：

Symbol	Meaning	Presentation	Example
G	era designator	(Text)	AD
y	year	(Number)	1996
M	month in year	(Text & Number)	July & 07
d	day in month	(Number)	10
h	hour in am/pm (1˜12)	(Number)	12
H	hour in day (0˜23)	(Number)	0
m	minute in hour	(Number)	30
s	second in minute	(Number)	55
S	fractional second	(Number)	978
E	day of week	(Text)	Tuesday
D	day in year	(Number)	189
F	day of week in month	(Number)	2 (2nd Wed in July)
w	week in year	(Number)	27
W	week in month	(Number)	2
a	am/pm marker	(Text)	PM
k	hour in day (1˜24)	(Number)	24
K	hour in am/pm (0˜11)	(Number)	0
z	time zone	(Text)	Pacific Standard Time
Z	time zone (RFC 822)	(Number)	-0800
v	time zone (generic)	(Text)	Pacific Time
V	time zone (location)	(Text)	United States (Los Angeles)
'	escape for text	(Delimiter)	'Date='
''	single quote	(Literal)	'o''clock'

實例:



main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/hello"
  />
<TextView
  android:id="@+id/currenttime"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  />
</LinearLayout>

AndroidSimpleDateFormat.java

package com.AndroidSimpleDateFormat;

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

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidSimpleDateFormat extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      TextView currentTime = (TextView)findViewById(R.id.currenttime);
    
      SimpleDateFormat formatter = new SimpleDateFormat("dd MMM yyyy  hh:mm:ss a");
      String now = formatter.format(new Date());
    
      currentTime.setText("Now is: " + now);
    
  }
}