java.util.Calendar#getInstance ( )源码实例Demo

private void settingInformation() {
    if(getIntent()!=null) {
        Calendar calendar = Calendar.getInstance();
        String date = String.format("%s, %d/%d", convertToDayOfWeek(calendar.get(Calendar.DAY_OF_WEEK)), calendar.get(Calendar.DAY_OF_MONTH), calendar.get(Calendar.MONTH));
        txtDate.setText(date);
        txtFee.setText(String.format("$ %.2f", getIntent().getDoubleExtra("total", 0.0)));
        txtEstimatedPayout.setText(String.format("$ %.2f", getIntent().getDoubleExtra("total", 0.0)));
        txtBaseFare.setText(String.format("$ %.2f", Common.baseFare));
        txtTime.setText(String.format("%s min", getIntent().getStringExtra("time")));
        txtDistance.setText(String.format("%s km", getIntent().getStringExtra("distance")));
        txtFrom.setText(getIntent().getStringExtra("start_address"));
        txtTo.setText(getIntent().getStringExtra("end_address"));

        //add icon_marker
        String[] location_end = getIntent().getStringExtra("location_end").split(",");
        LatLng dropOff = new LatLng(Double.parseDouble(location_end[0]), Double.parseDouble(location_end[1]));

        mMap.addMarker(new MarkerOptions().position(dropOff)
                .title("Drop Off Here")
                .icon(BitmapDescriptorFactory.fromResource(R.drawable.icon_destination_marker)));

        mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(dropOff, 12.0f));
    }
}
 

public void testSMTP(){
    TimeZone timeZone = TimeZone.getTimeZone("GMT-3");
    Calendar cal = Calendar.getInstance(timeZone);
    cal.set(2003,5,8,10,11,12);
    String text = DateFormatUtils.format(cal.getTime(), 
                    DateFormatUtils.SMTP_DATETIME_FORMAT.getPattern(), timeZone,
                    DateFormatUtils.SMTP_DATETIME_FORMAT.getLocale());
    assertEquals("Sun, 08 Jun 2003 10:11:12 -0300", text);
    text = DateFormatUtils.format(cal.getTime().getTime(), 
                    DateFormatUtils.SMTP_DATETIME_FORMAT.getPattern(), timeZone,
                    DateFormatUtils.SMTP_DATETIME_FORMAT.getLocale());
    assertEquals("Sun, 08 Jun 2003 10:11:12 -0300", text);
    text = DateFormatUtils.SMTP_DATETIME_FORMAT.format(cal);
    assertEquals("Sun, 08 Jun 2003 10:11:12 -0300", text);
    
    // format UTC
    text = DateFormatUtils.formatUTC(cal.getTime().getTime(), 
                    DateFormatUtils.SMTP_DATETIME_FORMAT.getPattern(),
                    DateFormatUtils.SMTP_DATETIME_FORMAT.getLocale());
    assertEquals("Sun, 08 Jun 2003 13:11:12 +0000", text);
}
 

private void assertEqualDuration(String message, String expected, int[] start, int[] end, String format) {
    Calendar cal1 = Calendar.getInstance();
    cal1.set(start[0], start[1], start[2], start[3], start[4], start[5]);
    cal1.set(Calendar.MILLISECOND, 0);
    Calendar cal2 = Calendar.getInstance();
    cal2.set(end[0], end[1], end[2], end[3], end[4], end[5]);
    cal2.set(Calendar.MILLISECOND, 0);
    long milli1 = cal1.getTime().getTime();
    long milli2 = cal2.getTime().getTime();
    String result = DurationFormatUtils.formatPeriod(milli1, milli2, format);
    if (message == null) {
        assertEquals(expected, result);
    } else {
        assertEquals(message, expected, result);
    }
}
 

@Test
public void shouldReturn10thNovember2010time8hour20minWhenConvertToLocalDateTime() {
    // given
    Calendar calendar = Calendar.getInstance();
    calendar.set(2010, 10, 10, 8, 20);
    Date dateToConvert = calendar.getTime();

    // when
    LocalDateTime localDateTime = DateToLocalDateTimeConverter.convertToLocalDateTime(dateToConvert);

    // then
    assertEquals(2010, localDateTime.get(ChronoField.YEAR));
    assertEquals(11, localDateTime.get(ChronoField.MONTH_OF_YEAR));
    assertEquals(10, localDateTime.get(ChronoField.DAY_OF_MONTH));
    assertEquals(8, localDateTime.get(ChronoField.HOUR_OF_DAY));
    assertEquals(20, localDateTime.get(ChronoField.MINUTE_OF_HOUR));
}
 

/**
 * 
 * 获取两个日期之间的天数
 * 例如：startDate=2016-04-03   endDate=2016-04-05
 *     返回：2
 *     
 * @author zhangshaobin
 * @created 2016年4月3日 下午午17:41:45
 * 
 * @param startDate
 * @param endDate
 * @return
 */
public static int getDatebetweenOfDayNum(Date startDate, Date endDate ) {
	try {
		startDate = parseDate(getDateFormat().format(startDate.getTime()), dateFormatPattern);
		endDate = parseDate(getDateFormat().format(endDate.getTime()), dateFormatPattern);
	} catch (ParseException e) {
		e.printStackTrace();
	}
	Calendar cal = Calendar.getInstance();
       cal.setTime(startDate);  
       long time1 = cal.getTimeInMillis();               
       cal.setTime(endDate);  
       long time2 = cal.getTimeInMillis();       
       long between_days=(time2-time1)/(1000*3600*24);  
         
      return Integer.parseInt(String.valueOf(between_days));  
}
 

/**
 * 按用户格式字符串距离今天的天数
 *
 * @param date   日期字符串
 * @param format 日期格式
 * @return
 */
public static int countDays(String date, String format) {
    long t = Calendar.getInstance().getTime().getTime();
    Calendar c = Calendar.getInstance();
    c.setTime(parse(date, format));
    long t1 = c.getTime().getTime();
    return (int) (t / 1000 - t1 / 1000) / 3600 / 24;
}
 

public DatePicker(ReadableMap options, Callback callback) {
    final Calendar c = Calendar.getInstance();
    this.callback = callback;
    year = options.hasKey("year") ? options.getInt("year") : c.get(Calendar.YEAR);
    month = options.hasKey("month") ? options.getInt("month") : c.get(Calendar.MONTH);
    day = options.hasKey("day") ? options.getInt("day") : c.get(Calendar.DAY_OF_MONTH);
}
 

public static boolean inSameDay(Date date1, Date Date2) {
	Calendar calendar = Calendar.getInstance();
	calendar.setTime(date1);
	int year1 = calendar.get(Calendar.YEAR);
	int day1 = calendar.get(Calendar.DAY_OF_YEAR);

	calendar.setTime(Date2);
	int year2 = calendar.get(Calendar.YEAR);
	int day2 = calendar.get(Calendar.DAY_OF_YEAR);

	if ((year1 == year2) && (day1 == day2)) {
		return true;
	}
	return false;
}
 

/**
 * Creates a time period for the week in which the specified date/time
 * falls, calculated relative to the specified time zone.
 *
 * @param time  the date/time (<code>null</code> not permitted).
 * @param zone  the time zone (<code>null</code> not permitted).
 * @param locale  the locale (<code>null</code> not permitted).
 *
 * @since 1.0.7
 */
public Week(Date time, TimeZone zone, Locale locale) {
    if (time == null) {
        throw new IllegalArgumentException("Null 'time' argument.");
    }
    if (zone == null) {
        throw new IllegalArgumentException("Null 'zone' argument.");
    }
    if (locale == null) {
        throw new IllegalArgumentException("Null 'locale' argument.");
    }
    Calendar calendar = Calendar.getInstance(zone, locale);
    calendar.setTime(time);

    // sometimes the last few days of the year are considered to fall in
    // the *first* week of the following year.  Refer to the Javadocs for
    // GregorianCalendar.
    int tempWeek = calendar.get(Calendar.WEEK_OF_YEAR);
    if (tempWeek == 1
            && calendar.get(Calendar.MONTH) == Calendar.DECEMBER) {
        this.week = 1;
        this.year = (short) (calendar.get(Calendar.YEAR) + 1);
    }
    else {
        this.week = (byte) Math.min(tempWeek, LAST_WEEK_IN_YEAR);
        int yyyy = calendar.get(Calendar.YEAR);
        // alternatively, sometimes the first few days of the year are
        // considered to fall in the *last* week of the previous year...
        if (calendar.get(Calendar.MONTH) == Calendar.JANUARY
                && this.week >= 52) {
            yyyy--;
        }
        this.year = (short) yyyy;
    }
    peg(calendar);
}
 

public EventWithoutYear(CalendarEvent baseEvent) {
    this.baseEvent = baseEvent;

    Calendar currCal = Calendar.getInstance();
    currCal.setTime(baseEvent.getDate());
    this.baseYear = currCal.get(Calendar.YEAR);
    int startYear = baseYear - X_YEAR;
    int endYear = baseYear + Y_YEAR;
    listYears = new ArrayList<>();
    for (int iteratedYear = startYear; iteratedYear <= endYear; iteratedYear++) {
        listYears.add(iteratedYear);
    }
}
 

/**
  * 获取一年中某周,星期几的日期
  *
  * @param yearNum   年
  * @param weekNum   那一周
  * @param dayOfWeek 周几
  * @return  日期
  */
 private static Date getDateOfYearWeek(int yearNum, int weekNum,
                                       int dayOfWeek) {
     Calendar cal = Calendar.getInstance();
     cal.setFirstDayOfWeek(Calendar.MONDAY);
     cal.set(Calendar.DAY_OF_WEEK, dayOfWeek);
     cal.setMinimalDaysInFirstWeek(DAYS_OF_A_WEEK);
     cal.set(Calendar.YEAR, yearNum);
     cal.set(Calendar.WEEK_OF_YEAR, weekNum);
     /*
      * cal.set(Calendar.HOUR_OF_DAY, 0); cal.set(Calendar.MINUTE, 0);
* cal.set(Calendar.SECOND, 0);
*/
     return cal.getTime();
 }
 

public static long getTimeDifference(final Date date1, final Date date2) {

        final Calendar dateCalendar1 = Calendar.getInstance();
        dateCalendar1.setTime(date1);
        final Calendar dateCalendar2 = Calendar.getInstance();
        dateCalendar2.setTime(date2);

        return (dateCalendar1.getTimeInMillis() - dateCalendar2.getTimeInMillis()) / 1000;
    }
 

/**
 * Generate Calendar object and return it
 * @param timestamp timestamp for which Calendar object to be created
 * @return Calendar object
 */
private Calendar toCalendar(long timestamp) {
    Calendar calendar = Calendar.getInstance();
    calendar.setTimeInMillis(timestamp);
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);
    return calendar;
}
 

public Date getDate()
{
    if (calendar == null) {
        calendar = Calendar.getInstance();
    }
    calendar.set(year, month, day);
    return calendar.getTime();
}
 

/**
 * Returns a JDK calendar type for given locale and time zone.
 * 
 * @param tz time zone
 * @param l locale
 * @return a calendar for given locale and time zone.
 */
public Calendar getCalendar(TimeZone tz, Locale locale) {
    /* TODO: uncomment following code once ICU fixes the calendar bugs. Then API versioning.
     * http://bugs.icu-project.org/trac/ticket/13548
     * http://bugs.icu-project.org/trac/ticket/13601
     
    if (shouldUseICU(locale)) {
        // Create ICU time zone instance.
        com.ibm.icu.util.TimeZone icu_tz = com.ibm.icu.util.TimeZone.getTimeZone(tz.getID());
        // Wrap ICU calendar into Java calendar type.
        return CalendarICU.wrap(com.ibm.icu.util.Calendar.getInstance(icu_tz, locale));
    }
    */
    return Calendar.getInstance(tz, locale);
}
 

public static String getDisplayDate(Context context, int datetime) {
    String[] weekTitle = context.getResources().getStringArray(R.array.weeks);

    int year = datetime / 10000;
    int month = (datetime % 10000) / 100 - 1;
    int day = datetime % 100;
    Date date = new GregorianCalendar(year, month, day).getTime();

    Calendar calendar = Calendar.getInstance();
    calendar.setTime(date);
    int week = calendar.get(calendar.DAY_OF_WEEK);

    return TimeUtils.convertByFormatter(date, "MM月dd日") + " " + weekTitle[week - 1];
}
 

TimeAxis(RrdGraph rrdGraph) {
	this.rrdGraph = rrdGraph;
	if (rrdGraph.im.xsize > 0) {
		this.secPerPix = (rrdGraph.im.end - rrdGraph.im.start) / Double.valueOf(rrdGraph.im.xsize);
	}
	this.calendar = Calendar.getInstance(Locale.getDefault());
	this.calendar.setFirstDayOfWeek(rrdGraph.gdef.firstDayOfWeek);
}
 

/**
 * 获得当前日期的上月的日期(MMM yyyy)
 * 
 * @return 日期
 */
public static String preMonth() {
	Calendar cal = Calendar.getInstance();
	cal.add(Calendar.MONTH, -1);
	return String.valueOf(dfMmmYyyy.format(cal.getTime()));
}
 

/**
 * See above.
 */
public static double secondInMinute()
{
   Calendar cal = Calendar.getInstance();
  return cal.get(Calendar.SECOND);
}
 

/**
 * Gets Date for <code> numberOfDays </code> ago.
 */
public static Date getDayBefore(Date date, int numberOfDays) {
    Calendar cal = Calendar.getInstance();
    cal.add(Calendar.DATE, -numberOfDays);
    return cal.getTime();
}