Convert date in string(Mon Jan 16:20:12 India Standard Time 2014) to java.util.date in JAVA

Question

I want to convert this (Mon Jan 16:20:12 India Standard Time 2014) Date in string to java.util.Date in java how can I do it. I want the date in the following format.

SimpleDateFormat formatter = new SimpleDateFormat(
                "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.US);

Actually the Date (Mon Jan 16:20:12 India Standard Time 2014) is argument from MFC application which will be launching a executable jar file and the date in string will be its argument. MFC Code that will launch the executable jar. with argument.

CString csCurrentTime = CTime::GetCurrentTime().Format("%a %b %X %Z %Y");
    TRACE(csCurrentTime);
    if (CreateProcess(m_csJrePath, TEXT(" -jar DbxUpldDwnld.jar %s",csCurrentTime), NULL, NULL, false, CREATE_NO_WINDOW, NULL, NULL, (LPSTARTUPINFOA)&siStartupInfo, &piProcessInfo) == false) {
        AfxMessageBox(_T("Please install Java Runtime Environment(JRE) on your PC\n Or JRE not found on given path in INI File."), MB_ICONERROR);
        CloseHandle(piProcessInfo.hProcess);
        CloseHandle(piProcessInfo.hThread);
        return;
    }

Also will it be possible to get the date with spaces as single argument in java. Please Help me, am new to MFC.

Answer 1

You need to use another SimpleDateFormat that has the format of your time-string to do the parsing. For your example, this one should work:

String time = "Mon Jan 16:20:12 India Standard Time 2014";
SimpleDateFormat parser = new SimpleDateFormat("E MMM HH:mm:ss z yyyy", Locale.US);
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.US);
System.out.println(formatter.format(parser.parse(time)));

As @TimB points out, all the date and time patterns can be found in the JavaDoc for SimpleDateFormat.

Answer 2

java.time

Update:

Thanks to Ole V.V.

For a more general solution, replace .parseDefaulting(ChronoField.DAY_OF_MONTH, date.getDayOfMonth()) with .parseDefaulting(ChronoField.ALIGNED_WEEK_OF_MONTH, 1) which will also simplify the solution by removing the need to obtain the LocalDate first.

Demo:

import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.TextStyle;
import java.time.temporal.ChronoField;
import java.util.Locale;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        DateTimeFormatter dtf = new DateTimeFormatterBuilder()
                                .parseCaseInsensitive()                              
                                .appendPattern("E MMM H:m:s")
                                .appendLiteral(' ')
                                .appendZoneText(TextStyle.FULL)
                                .appendLiteral(' ')
                                .appendPattern("u")
                                .parseDefaulting(ChronoField.ALIGNED_WEEK_OF_MONTH, 1)                                
                                .toFormatter(Locale.ENGLISH);

        // Test
        Stream.of(
                    "Mon Jan 16:20:12 India Standard Time 2014",
                    "Mon Feb 16:20:12 India Standard Time 2014"
        ).forEach(s -> System.out.println(ZonedDateTime.parse(s, dtf)));
    }        
}

Output:

2014-01-06T16:20:12+05:30[Asia/Kolkata]
2014-02-03T16:20:12+05:30[Asia/Kolkata]

Original answer:

The legacy date-time API (java.util date-time types and their formatting API, SimpleDateFormat) is outdated and error-prone. It is recommended to stop using it completely and switch to java.time, the modern date-time API^*.

Solution using the modern API:

Your date-time string does not have day-of-month. It means that you need to provide a day-of-month to the DateTimeFormatter which you can do by using DateTimeFormatterBuilder#parseDefaulting. In order to obtain the first Monday of the month, the idiomatic way is to use TemporalAdjusters.firstInMonth.

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.Month;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.TextStyle;
import java.time.temporal.ChronoField;
import java.time.temporal.TemporalAdjusters;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        String strDateTime = "Mon Jan 16:20:12 India Standard Time 2014";

        LocalDate date = LocalDate.of(2014, Month.JANUARY, 1)
                                .with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));

        DateTimeFormatter dtf = new DateTimeFormatterBuilder()
                                .parseCaseInsensitive()
                                .parseDefaulting(ChronoField.DAY_OF_MONTH, date.getDayOfMonth())
                                .appendPattern("E MMM H:m:s")
                                .appendLiteral(' ')
                                .appendZoneText(TextStyle.FULL)
                                .appendLiteral(' ')
                                .appendPattern("u")
                                .toFormatter(Locale.ENGLISH);

        ZonedDateTime zdt = ZonedDateTime.parse(strDateTime, dtf);
        System.out.println(zdt);
    }
}

Output:

2014-01-06T16:20:12+05:30[Asia/Kolkata]

For any reason, if you need to convert this object of ZonedDateTime to an object of java.util.Date, you can do so as follows:

Date date = Date.from(zdt.toInstant());

Learn more about the the modern date-time API^* from Trail: Date Time.

---

^{* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.}