Question

我想将格式为MM/dd/yyyy HH:mm的{{3}}转换为PST Time。

我试过的代码如下。目前我在IST Time Zone并使用JDK1.7。

以下代码生成输出This is the Code Test : 08/31/2015 07:20 MST

我怀疑它是否真的是MST！因为MST Time在这里显示为20:50所以我教过它，它应该显示为8:50，考虑到am / pm（12hr）时钟。

这让我很困惑 - 我想知道出了什么问题？

   /**
     * 
     * Read a Date in the Format of MM/dd/yyyy HH:mm which is a (PST) Time Zone.
     * Convert it to MST Time Zone and Save.
     * 
     * Step 1 : Set Timezone as PST to Date in format of MM/dd/yyyy HH:mm,
     * Step 2 : Convert PST to MST Time,
     * Step 3 : Convert MST Time to Date in format of MM/dd/yyyy HH:mm.
     * 
     * Eg:  PST Time Now -> 08/31/2015 19:50;
     *      MST Time Now -> 08/31/2015 20:50;
     * 
     *
     */

 package dates;

        import java.text.DateFormat;
        import java.text.ParseException;
        import java.text.SimpleDateFormat;
        import java.util.Calendar;
        import java.util.Date;
        import java.util.Locale;
        import java.util.TimeZone;


        public class DateUtilities {

            public static void main(String[] args) {
                String dateInString = "08/31/2015 19:50";
                System.out.println("This is the Code Test"+MstTimeNow(step1(StringToDate(dateInString))));
                // step2(step1(StringToDate(dateInString)));
            }


            // String To Date
            public static Date StringToDate(String dateInString) {
                Date date = null;
                try {
                    SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm");
                    date = sdf.parse(dateInString);
                    // System.out.println("String To Date "+date);
                } catch (ParseException e) {
                    e.printStackTrace();
                }
                return date;
            }


            // To Set TimeZone as PST
            public static Calendar step1(Date date) {
                Calendar cal = Calendar.getInstance();
                TimeZone tz = TimeZone.getTimeZone("PST");
                cal.setTimeZone(tz);
                cal.setTime(date);
                // System.out.println("Get Calendar PST Time: "+cal.getTime() +" TimeZone "+cal.getTimeZone());
                return cal;
            }

            // Calendar To MST Time
            public static String MstTimeNow(Calendar cal) {
                DateFormat formatter = new SimpleDateFormat("MM/dd/yyyy HH:mm z");
                formatter.setCalendar(cal);
                formatter.setTimeZone(TimeZone.getTimeZone("MST"));
                String mstTimeString = formatter.format(cal.getTime());
                // System.out.println("MST time Now is : "+mstTimeString);
                return mstTimeString;
            }
    }

由MST Time给出的

Solution产生的输出低于预期值！

Input String : 08/31/2015 19:50
Local Date Time: 2015-08-31T19:50
Zoned Date Time PST: 2015-08-31T19:50-07:00[America/Los_Angeles]
Zoned Date Time MST: 2015-08-31T20:50-06:00[America/Denver]

Answer 1

如果您可以使用新的Java时间API，您的代码可以更简单：

String input = "08/31/2015 19:50";
DateTimeFormatter fmt = DateTimeFormatter.ofPattern("MM/dd/yyyy HH:mm")

LocalDateTime ldt = LocalDateTime.parse(input, fmt);
ZonedDateTime pst = ZonedDateTime.of(ldt, ZoneId.of("America/Los_Angeles"));
ZonedDateTime mst = pst.withZoneSameInstant(ZoneId.of("America/Denver"));

Answer 2

我在Java1.7中尝试了以下代码，以下代码仅是从PST转换为MST的一部分。：P

public static Date convertPstToMst(String dateInString){
          Date mstDate = null;

          // Set Default TimeZone as PST    
          SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm");
          sdf.setTimeZone(TimeZone.getTimeZone(PST_TIMEZONE));

          try { 
                Calendar pstCal = Calendar.getInstance(TimeZone.getTimeZone(PST_TIMEZONE));
                pstCal.setTime(sdf.parse(dateInString));

                    String pstTime = ((pstCal.get(Calendar.MONTH)+1)+"/"+pstCal.get(Calendar.DATE)+"/"+pstCal.get(Calendar.YEAR)+" "+pstCal.get(Calendar.HOUR_OF_DAY)+":"+pstCal.get(Calendar.MINUTE));
                    System.out.println(pstTime);

                    pstCal.setTimeZone(TimeZone.getTimeZone(MST_TIMEZONE));
                    String mstTime = ((pstCal.get(Calendar.MONTH)+1)+"/"+pstCal.get(Calendar.DATE)+"/"+pstCal.get(Calendar.YEAR)+" "+pstCal.get(Calendar.HOUR_OF_DAY)+":"+pstCal.get(Calendar.MINUTE));
                    System.out.println(mstTime);
                    // Converting String to Date
                    mstDate = convertStringToDate(mstTime);

            } catch (ParseException e) {
                e.printStackTrace();
            }
          return mstDate;
      }

将日期从PST转换为MST TimeZone

2 个答案: