How to get a month as an integer from the given date and print as month name format ("MMM")

Question

I am new to Java and couldnt retrieve the month while using the below code instead month value is set to 0. Please advise the mistakes that i have done here.

*

for(int i=0;i<this.input.size();i++)
     {
         SimpleDateFormat sf = new SimpleDateFormat("dd/mm/yyyy");

         Date purchasedate;
        try {
            String details  = input.get(i);
            String[] detailsarr = details.split(",");
            purchasedate = sf.parse(detailsarr[1]);
            Calendar cal = Calendar.getInstance();
            cal.setTime(purchasedate);
            int month = cal.get(Calendar.MONTH);

* After getting the above month as an integer, Could you please advise if there is anyway to print the above month value as "MMM" format?

Answer 1

tl;dr

LocalDate.parse(          // Represent a date-only value, without time-of-day and without time zone.
    "23/01/2018" ,        // Tip: Use standard ISO 8601 formats rather than this localized format for data-exchange of date-time values.
    DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) 
)                         // Return a `LocalDate` object.
.getMonth()               // Return a `Month` enum object representing the month of this date.
.getDisplayName(          // Automatically localize, generating text of the name of this month.
    TextStyle.SHORT ,     // Specify (a) how long or abbreviated, and (b) specify whether used in stand-alone or combo context linguistically (irrelevant in English). 
    Locale.US             // Specify the human language and cultural norms to use in translation.
)                         // Returns a `String`.

See this code run live at IdeOne.com.

Jan

java.time

The modern approach uses the java.time classes that supplanted the terrible Date/Calendar/SimpleDateFormat classes.

ISO 8601

Tip: When exchanging date-time values as text, use the ISO 8601 standard formats rather than using text meant for presentation to humans. For a date-only value, that would be YYYY-MM-DD such as 2018-01-23.

LocalDate

The LocalDate class represents a date-only value without time-of-day and without time zone.

DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) ;
LocalDate ld = LocalDate.parse( "23/01/2018" , f ) ;

Month enum

Retrieve the month as a Month enum object.

Month m = ld.getMonth() ;

Localize

Ask that Month enum to generate a String with text of the name of the month. The getDisplayName method can automatically localize for you. To localize, specify:

• TextStyle to determine how long or abbreviated should the string be. Note that in some languages you may need to choose stand-alone style depending on context in which you intend to use the result.
• Locale to determine:
  • The human language for translation of name of day, name of month, and such.
  • The cultural norms deciding issues of abbreviation, capitalization, punctuation, separators, and such.

Code:

String output = m.getDisplayName( TextStyle.SHORT , Locale.US ) ;

Use enum, not integer

Notice that we had no use of an integer number to represent the month. Using an enum object instead makes our code more self-documenting, ensures valid values, and provides type-safety.

So I strongly recommend passing around Month objects rather than mere int integer numbers. But if you insist, call Month.getMonthValue() to get a number. The numbering is sane, 1-12 for January-December, unlike the legacy classes.

int monthNumber = ld.getMonthValue() ;

---

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • Later versions of Android bundle implementations of the java.time classes.
  • For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Answer 2

java.time

    DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("dd/MM/uuuu");

    String dateStringFromInput = "29/08/2018";
    LocalDate purchasedate = LocalDate.parse(dateStringFromInput, dateFormatter);

    int monthNumber = purchasedate.getMonthValue();
    System.out.println("Month number is " + monthNumber);

Running the above snippet gives this output:

Month number is 8

Note that contrary to Calendar LocalDate numbers the months the same way humans do, August is month 8. However to get the month formatted into a standard three letter abbreviation we don’t need the number first:

    Locale irish = Locale.forLanguageTag("ga");
    DateTimeFormatter monthFormatter = DateTimeFormatter.ofPattern("MMM", irish);

    String formattedMonth = purchasedate.format(monthFormatter);
    System.out.println("Formatted month: " + formattedMonth);

Formatted month: Lún

Please supply your desired locale where I put Irish/Gaelic. Java knows the month abbreviations in a vast number of languages.

What went wrong in your code?

Apart from using the long outdated date and time classes, SimpleDateFormat, Date and Calendar, format pattern letters are case sensitive (this is true with the modern DateTimeFormatter too). To parse or format a month you need to use uppercase M (which you did correctly in your title). Lowercase m is for minute of the hour. SimpleDateFormat is troublesome here (as all too often): rather than telling you something is wrong through an exception it just tacitly defaults the month to January. Which Calendar in turn returns to you as month 0 because it unnaturally numbers the months from 0 through 11.

Links

• Oracle tutorial: Date Time explaining how to use java.time.
• Question: Why is January month 0 in Java Calendar?

Answer 3

Simple way of doing this is

Calendar cal = Calendar.getInstance();
Date d = cal.getTime();     
SimpleDateFormat sdf = new SimpleDateFormat("MMM");
System.out.println(sdf.format(d));

In your case modify snippet like below:

 SimpleDateFormat sf = new SimpleDateFormat("dd/mm/yyyy");
 Date purchasedate;
 try {
        String details  = input.get(i);
        String[] detailsarr = details.split(",");
        purchasedate = sf.parse(detailsarr[1]);
        SimpleDateFormat sdf = new SimpleDateFormat("MMM");
        String month = sdf.format(purchasedate);
   }