[안드로이드] View에 날짜를 보여줄 경우 포맷 관련

출처 : http://www.tutorialsbuzz.com/2014/03/android-system-date-time-format.html

we use make use of Calender class of java.util package , the static method getInstance of Calender class returns the  instance of Calender and this object can produce all the time field values  needed to implement the date-time format

 Calendar c = Calendar.getInstance();

After getting calendar Instance , we required a formatted object for date and time.

The SimpleDateFormat Class is used for setting the format , the constructor of this class takes the pattern describing what strings are to produced

SimpleDateFormat format = new SimpleDateFormat("dd:MMMM:yyyy HH:mm:ss ");
String formatdate=format(c.getTime());

file : activity_main.xml

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/display"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:textSize="22sp" />

</RelativeLayout>

file : MainActivity

package com.example.sysdatetime;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {

 TextView tv;
 Button btn;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  tv = (TextView) findViewById(R.id.display);

  Calendar c = Calendar.getInstance();

  SimpleDateFormat format1, format2, format3, format4, format5;

  format1 = new SimpleDateFormat("dd:MM:yyyy:HH:mm:ss ");

  format2 = new SimpleDateFormat("dd-MM-yyyy-HH-mm-ss");

  format3 = new SimpleDateFormat("dd-MMMM-yyyy-HH-mm-ss");

  format4 = new SimpleDateFormat("dd/MMM/yyyy/HH/mm/ss");

  format5 = new SimpleDateFormat("dd_MM_yy_HH_mm_ss a");

  tv.setText(format1.format(c.getTime()) + "\n\n"
    + format2.format(c.getTime()) + "\n\n"
    + format3.format(c.getTime()) + "\n\n"
    + format4.format(c.getTime()) + "\n\n"
    + format5.format(c.getTime()));

 }
}

In this below table you can see the patterns description for date time and also the separator which is used for formatting.

Date format 

Date Format	Description	Value
d	Single digit date eg 1	1
dd	double digit date eg 01	01
M	Single digit month eg: 1	1
MM	Double digit month eg: 01	01
MMM	three letter abbreviation for month ex: jan	jan
MMMM	month spelled out in full ex : january	january
yy	double digit year ex : 14	14
yyyy	four digit year ex : 2014	2014

Time Format 

Time Format	Description	Value
h	single digit hours in 12hours format	9
hh	double digit hours in 12 hour format	09
H	single digit hours in 24 hour format	8AM as 8 8PM as 20
HH	double digit hours in 24 hour format	8AM as 08 8PM as 20
m	single digit minute	9
mm	double digit minute	09
s	single digit second	9
ss	double digit second	09
a	Marker	am/pm

Separator 

Format	Description
" . "	Dots or full stops
" _ "	Hyphens or dashes
" "	Spaces
" : "	colon mostly used between time
" / "	Slash