How to Parse Case-Insensitive Strings with Jsr310 Datetimeformatter

How to parse case-insensitive strings with JSR-310 DateTimeFormatter?

And there is... according to the User Guide (offline, see JavaDoc instead), you should use DateTimeFormatterBuilder to build a complex DateTimeFormatter

e.g.

DateTimeFormatterBuilder builder = new DateTimeFormatterBuilder();
builder.parseCaseInsensitive();
builder.appendPattern("dd-MMM-yyyy");
DateTimeFormatter dateFormat = builder.toFormatter();

How to handle upper or lower case in JSR 310?

DateTimeFormatters are strict and case sensitive by default. Use a DateTimeFormatterBuilder and specify parseCaseInsensitive() to parse case insensitive.

DateTimeFormatter formatter = new DateTimeFormatterBuilder()
    .parseCaseInsensitive()
    .appendPattern("yy-MMM-dd")
    .toFormatter(Locale.US);

To be able to parse numeric months (ie. "15-01-12"), you also need to specify parseLenient().

DateTimeFormatter formatter = new DateTimeFormatterBuilder()
    .parseCaseInsensitive()
    .parseLenient()
    .appendPattern("yy-MMM-dd")
    .toFormatter(Locale.US);

You can also be more verbose to specify only the month part as case insensitive/lenient:

DateTimeFormatter formatter = new DateTimeFormatterBuilder()
    .appendPattern("yy-")
    .parseCaseInsensitive()
    .parseLenient()
    .appendPattern("MMM")
    .parseStrict()
    .parseCaseSensitive()
    .appendPattern("-dd")
    .toFormatter(Locale.US);

In theory, this could be faster, but I'm not sure if it is.

PS: If you specify parseLenient() before the year part, it will also parse 4 digit years (ie. "2015-JAN-12") correctly.

While parsing date with upper case month name I get java.time.format.DateTimeParseException

you can configure your DateTimeFormatter to ignore cases

DateTimeFormatter formatter = new DateTimeFormatterBuilder()
                .parseCaseInsensitive()
                .appendPattern("dd-MMM-yy")
                .toFormatter(Locale.getDefault());

java.time.format.DateTimeParseException: Text could not be parsed at index 3

The following code works. The problem is you are using "JAN" instead of "Jan".
DateTimeFormatter does not recognize that it seems. and also change the pattern to
"d-MMM-yyyy".

  String date1 ="01-Jan-2017";
  String date2 = "02-Feb-2017";

  DateTimeFormatter df = DateTimeFormatter.ofPattern("d-MMM-yyyy");
  LocalDate  d1 = LocalDate.parse(date1, df);
  LocalDate  d2 = LocalDate.parse(date2, df);

  Long datediff = ChronoUnit.DAYS.between(d1,d2);  

Source: https://www.mkyong.com/java8/java-8-how-to-convert-string-to-localdate/

JSR310 Year.parse() throws DateTimeParseException with values 1000

needs to be padded to 4 digits

Year.parse(String.format("%04d", i));

Parsing year: 2000
Parsing year: ....
Parsing year: 4
Parsing year: 3
Parsing year: 2
Parsing year: 1
Parsing year: 0

If you wanted to parse before year 0, you could use

Year.parse("-0001");

Java 8 DateTimeFormatter for month in all CAPS not working

Answering this question because most of us might not know JSR 310. Hence would search for java 8 LocalDateTime ignore case.

@Test
public void testDateFormat(){
    DateTimeFormatter formatter= new DateTimeFormatterBuilder().parseCaseInsensitive().appendPattern("dd-MMM-yyyy HH:mm:ss").toFormatter();
    LocalDateTime dateTime = LocalDateTime.parse("04-NOV-2015 16:00:00", formatter);
    System.out.println(dateTime.getYear());
}

**UPDATE*

To locale

DateTimeFormatter parser = new DateTimeFormatterBuilder().parseCaseInsensitive() .appendPattern("dd-MMM-yyyy HH:mm:ss.SS").toFormatter(Locale.ENGLISH)

java.time.format.DateTimeParseException for dd-MMM-yyyy format

The reason is that parsing is case sensitive by default and the formatter doesn't recognize "jan". It would only recognize "Jan".

You can construct a case-insensitive parser by using a DateTimeFormatterBuilder and calling parseCaseInsensitive():

Changes the parse style to be case insensitive for the remainder of the formatter.

Parsing can be case sensitive or insensitive - by default it is case sensitive. This method allows the case sensitivity setting of parsing to be changed.

DateTimeFormatter dTF = 
    new DateTimeFormatterBuilder().parseCaseInsensitive()
                                  .appendPattern("dd-MMM-yyyy")
                                  .toFormatter();

Multiple case insensitive strings replacement

You can try to use regex to archive it

Example

String str = "Dang DANG dAng dang";
//replace all dang(ignore case) with Abhiskek
String result = str.replaceAll("(?i)dang", "Abhiskek");
System.out.println("After replacement:" + "   " + result);

Result:

After replacement: Abhiskek Abhiskek Abhiskek Abhiskek

EDIT

---

String[] old = {"ABHISHEK","Name"};
String[] nw = {"Abhi","nick name"};
String s="My name is Abhishek";
//make sure old and nw have same size please
for(int i =0; i < old.length; i++) {
    s = s.replaceAll("(?i)"+old[i], nw[i]);
}
System.out.println(s);

Result:

My nick name is Abhi

Basic ideal: Regex ignore case and replaceAll()

From the comment @flown (Thank you) you need to use

str.replaceAll("(?i)" + Pattern.quote(old[i]), nw[i]);

Because regex treats some special character with a different meaning, ex: . as any single character

So using the Pattern.quote will do this.

---

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