Simpledateformat Ignoring Month When Parsing

SimpleDateFormat ignoring month when parsing

Try:

"yyyy-MM-dd'T'HH:mm:ss"

MM means month. mm means minutes. See the documentation for SimpleDateFormat for more details of the supported date and time patterns.

Java SimpleDateFormat Seemingly Ignoring Month and Day

I think your pattern is a little off. I'm suprised you're not seeing an IllegalArgumentException. Try using the following pattern with lower case y's and see if that resolves your issue:

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

Why does SimpleDateFormat.parse not throw an exception here?

Any idea what's wrong?

This is one of the places where SimpleDateFormat gets really troublesome. When trying to parse 1980-04-25 using the pattern yyyyMMdd it parses 1980 as year as expected, then -0 as month since it was supposed to be two characters, then 4 as day of month even though it was supposed to be two characters too. It ignores the -25 because it has done parsing.

A SimpleDateFormat with standard settings also ignores the fact that there is no month -0. It takes it as 0, so the month before January 1980, which is why you get December 1979.

SimpleDateFormat is notoriously troublesome, and Date is poorly designed too. Both are long outdated. I recommend you don’t use SimpleDateFormat. Ever.

java.time

private static final String[] dateFormats
        = "yyyyMMdd,yyyy/MM/dd,yyyy-MM-dd,dd/MM/yyyy,dd-MM-yyyy,dd-MMM-yyyy,yyyy MM dd"
                .split(",");

public static LocalDate parseAllDateFormats(String date) {
    if (date == null) {
        return null;
    }
    for (String format : dateFormats) {
        try {
            System.out.println("trying " + format);                
            DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern(format, Locale.ENGLISH);
            return LocalDate.parse(date, dateFormatter);
        }
        catch (DateTimeParseException e) {
            // Ignore, try next format
        }
    }
    return null;
}

Let’s try it with your example string:

    System.out.println(parseAllDateFormats("1980-04-25"));

Output is the expected:

trying yyyyMMdd
trying yyyy/MM/dd
trying yyyy-MM-dd
1980-04-25

I am using java.time, the modern Java date and time API. Compared to the old date-time classes it is so much nicer to work with. The modern DateTimeFormatter can resolve the parsed values into a date in three styles: strict, smart and lenient. Smart is the default where it will only accept month number from 1 through 12. Also LocalDate.parse will insist on parsing the entire string, or it will throw an exception.

Compared to your code I also made a couple of minor modifications. For most purposes I would have made an array of DateTimeFormatter (not of String), but it would not have allowed me to print trying yyyyMMdd, so here I didn’t. I put curly braces in the first if statement. I specified locale on the formatter because month abbreviations differ between languages and I want to control which language is used. I catch the specific DateTimeParseException and I added a comment why I ignore it because otherwise ignoring an exception is a bad, bad thing. At the bottom of your method you should also consider throwing an exception if no format worked rather than returning null.

Java 6

be aware I'm stuck with java6 here.

• The java.time classes are built into Java 8 and later, as well as Android 26 and later.
• ✅ Most of the java.time functionality is back-ported to Java 6 & Java 7 in the ThreeTen-Backport project.
• Further adapted for earlier Android (<26) in ThreeTenABP. See How to use ThreeTenABP….

Links

• Related question: SimpleDateFormat giving wrong date instead of error
• Related question: SimpleDateFormat parse(string str) doesn't throw an exception when str = 2011/12/12Simpledateformat Ignoring Month When Parsinga?
• Oracle tutorial: Date Time explaining how to use java.time.

Simple date format reading month incorrectly

This is because DD means day in year. You want dd for day in month. See SimpleDateFormat Javadoc

I suggest you use HH for 24 hour time.

SimpleDateFormat issue when parsing a String in ISO 8601 format

The date format passed to your SimpleDateFormat is "dd/MM/yy", while the date you are trying to parse is of the format "yyyy-MM-dd". Try this instead:

Date login = new SimpleDateFormat("yyyy-MM-dd HH:mm:ssZ").parse("2017-05-16 06:24:36-0700");

---

As a side note, depending on which version of Java you are using, I would recommend using the new java.time package (JDK 1.8+) or the back port of that package (JDK 1.6+) instead of the outdated (no pun intended) Date and/or Calendar classes.

Instant login = Instant.from(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ssZ").parse("2017-05-16 06:24:36-0700"));

SimpleDateFormat returns a strange value in java

Remember that 'm' means minutes and 'M' means months

http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html

---

Related Topics