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DateTimeFormatter could not be parsed using "HH:mm E d MMM YYYY" pattern

I am retrieving a date/time from an external data source, this is returned in the following format "14:30 Sat 05 May" with no year.
I've been trying to parse this to a LocalDateTime unsuccessfully. The data returned does not return a year as it is an assumption that we are always operating in the current year.
//date to parse
String time = "14:30 Sat 05 May";
//specify date format matching above string
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm E d MMM YYYY") ;
//we do not have a year returned but i can make the assumption we use the current year
LocalDateTime formatDateTime = LocalDateTime.parse(time, formatter).withYear(2018);
The above code throws the following exception
Exception in thread "main" java.time.format.DateTimeParseException: Text '14:30 Sat 05 May' could not be parsed at index 16
Any help appreciated.

Default year
Specify a default year in your DateTimeFormatter, using the DateTimeFormatterBuilder class by calling parseDefaulting and specifying the year-field with ChronoField.YEAR.
DateTimeFormatter formatter = new DateTimeFormatterBuilder()
.appendPattern("HH:mm E d MMM")
.parseDefaulting(ChronoField.YEAR, 2018) // <------
.toFormatter(Locale.ENGLISH);
With this formatter instead of yours:
LocalDateTime.parse( "14:30 Sat 05 May" , formatter )
…I get:
2018-05-05T14:30
See that code run live at IdeOne.com.
Points to note:
Your format pattern string needs to match the parsed string end-to-end. So when your date-time string doesn’t have a year in it, don’t include YYYY in your format pattern.
In any case don’t use uppercase YYYY here. It’s for week-based year and only useful with week numbers. If your string had had a year in it, you should have used uuuu or lowercase yyyy.
Make it a habit to give explicit locale to your formatter so you know it also works on other computers, and on yours when one day you play with its settings.

LocalDateTime.parse() expects a String that represents a valid date, which the year part.
You cannot set the year after invoking this method in this way :
LocalDateTime.parse(time, formatter).withYear(2018);
The year has to be set before because otherwise parse() throws DateTimeParseException.
As a workaround you may concatenate the current year in the input.
Some additional notes:
the pattern you use and the input date in textual format don't match exactly.
You don't specify a Locale for the parsing operation.
It means that it will work according to the local where the JVM is run.
To ensure that it works in any case, you should specify the Locale.
So you could try something like :
//date to parse
String time = "14:30 Sat 05 May";
time += " " + LocalDate.now().getYear();
//specify date format matching above string
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm EEE dd MMM yyyy", Locale.US) ;
//we do not have a year returned but i can make the assumption we use the current year
LocalDateTime formatDateTime = LocalDateTime.parse(time, formatter);

LocalDate: parse MM-yyyy

I get java.time.format.DateTimeParseException after attempt to do following:
LocalDate.parse( "09-2017" , DateTimeFormatter.ofPattern("MM-yyyy") )
What is wrong? Is there any utility in Java to check dateString formats?

A LocalDate needs the day, month and year to be built. Your input has only the month and year. You'll have to choose an arbitrary day and set it to the parsed object to create a LocalDate.
You can either parse it to a java.time.YearMonth, and then choose the day:
DateTimeFormatter fmt = DateTimeFormatter.ofPattern("MM-yyyy");
YearMonth ym = YearMonth.parse("09-2017", fmt);
LocalDate dt = ym.atDay(1); // choose whatever day you want
Or you can use a java.time.format.DateTimeFormatterBuilder with a java.time.temporal.ChronoField to define a default value for the day:
DateTimeFormatter fmt = new DateTimeFormatterBuilder()
// month-year
.appendPattern("MM-yyyy")
// default value for day
.parseDefaulting(ChronoField.DAY_OF_MONTH, 1)
// create formatter
.toFormatter();
LocalDate dt = LocalDate.parse("09-2017", fmt);
PS: If you just want to check if the input is correct, just parsing it to a YearMonth is enough (it already checks if the parsed values are valid).

Why my pattern("yyyyMM") cannot parse with DateTimeFormatter (java 8)

When I using SimpleDateFormat, it can parse.
SimpleDateFormat format = new SimpleDateFormat("yyyyMM");
format.setLenient(false);
Date d = format.parse(date);
But When I use Java 8 DateTimeFormatter,
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMM");
LocalDate localDate = LocalDate.parse(date, formatter);
it throws
java.time.format.DateTimeParseException: Text '201510' could not be parsed: Unable to obtain LocalDate from TemporalAccessor: {Year=2015, MonthOfYear=10},ISO of type java
.time.format.Parsed
String value for date is "201510".

Ask yourself the question: which day should be parsed with the String "201510"? A LocalDate needs a day but since there is no day in the date to parse, an instance of LocalDate can't be constructed.
If you just want to parse a year and a month, you can use the YearMonth object instead:
YearMonth localDate = YearMonth.parse(date, formatter);
However, if you really want to have a LocalDate to be parsed from this String, you can build your own DateTimeFormatter so that it uses the first day of the month as default value:
DateTimeFormatter formatter = new DateTimeFormatterBuilder()
.appendPattern("yyyyMM")
.parseDefaulting(ChronoField.DAY_OF_MONTH, 1)
.toFormatter();
LocalDate localDate = LocalDate.parse(date, formatter);

You can use a YearMonth and specify the day you want (say the first for example):
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMM");
LocalDate localDate = YearMonth.parse(date, formatter).atDay(1);
Or if the day is irrelevant, just use a YearMonth.

how to get month name using current date as input in function

How do I create a function which take current date and return month name?
I have only date its not current date it can be any date like 2013/4/12 or 23/8/8.
Like String monthName("2013/9/11");
when call this function return the month name.

This should be fine.
It depends on the format of date.
If you try with February 1, 2011
it would work, just change this string "MMMM d, yyyy" according to your needs.
Check this for all format patterns.
And also, months are 0 based, so if you want January to be 1, just return month + 1
private static int getMonth(String date) throws ParseException{
Date d = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH).parse(date);
Calendar cal = Calendar.getInstance();
cal.setTime(d);
int month = cal.get(Calendar.MONTH);
return month + 1;
}
If you want month name try this
private static String getMonth(String date) throws ParseException{
Date d = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH).parse(date);
Calendar cal = Calendar.getInstance();
cal.setTime(d);
String monthName = new SimpleDateFormat("MMMM").format(cal.getTime());
return monthName;
}
As I said, check web page I posted for all format patterns. If you want only 3 characters of month, use "MMM" instead of "MMMM"

java.time
I am contributing the modern answer.
System.out.println(LocalDate.of(2013, Month.SEPTEMBER, 11) // Define the date
.getMonth() // Get the month
.getDisplayName( // Get the month name
TextStyle.FULL_STANDALONE, // No abbreviation
Locale.ENGLISH)); // In which language?
Output is:
September
Use LocalDate from java.time, the modern Java date and time API, for a date.
Use LocalDate.getMonth() and Month.getDisplayName() to get the month name.
Avoid Date, Calendar and SimpleDateFormat used in the old answers from 2013. Those classes are poorly designed, troublesome and long outdated. The modern API is so much nicer to work with. Also avoid switch/case for this purpose since the month names are already built in, and using the library methods gives you clearer, terser and less error-prone code.
Use LocalDate
LocalDate today = LocalDate.now(ZoneId.systemDefault());
LocalDate aDate = LocalDate.of(2013, Month.SEPTEMBER, 11); // 2013/9/11
LocalDate anotherDate = LocalDate.of(2023, 8, 8); // 23/8/8
If you are getting the date as string input, parse the string using a DateTimeFormatter:
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("u/M/d");
String stringInput = "2013/4/12";
LocalDate date = LocalDate.parse(stringInput, dateFormatter);
System.out.println(date);
2013-04-12
Use LocalDate.getMonth() and Month.getDisplayName()
To get the month name you first need to decide in which language you want the month name. I am taking English as an example and still using date from the previous snippet:
String monthName = date.getMonth()
.getDisplayName(TextStyle.FULL_STANDALONE, Locale.ENGLISH);
System.out.println(monthName);
April
Java knows the month names in a wealth of languages. If you want the month name in the user’s language, pass Locale.getDefault() as the second argument to getDisplayName().
Link
Oracle tutorial: Date Time explaining how to use java.time.

Use this code -
Calendar calendar = new GregorianCalendar();
calendar.setTime(date);
int month = calendar.get(Calendar.MONTH);
So now you have month number, you can use switch case to get name for that month.
If your date is in string format use this-
Date date = new SimpleDateFormat("yyyy-MM-dd").format(d)

Simple solution to get current month by name:
SimpleDateFormat formatterMonth = new SimpleDateFormat("MMMM");
String currentMonth = formatterMonth.format(new Date(System.currentTimeMillis()));
Function to get any month by name using format 2013/9/11: (not tested)
private String monthName(String dateToCheck){
Date date = new Date();
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd");
date = formatter.parse(dateToCheck);
SimpleDateFormat formatterMonth = new SimpleDateFormat("MMMM");
return formatterMonth.format(new Date(date.getTime()));
}

I am using a function like this:
public String getDate(String startDate) throws ParseException {
#SuppressLint("SimpleDateFormat") SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date d = null;
try {
d = sdf.parse(startDate);
sdf.applyPattern("MMMM dd, YYYY"); //this gives output as=> "Month date, year"
} catch (Exception e) {
Log.d("Exception", e.getLocalizedMessage());
}
return sdf.format(d);
}

You can obtain the "number" of the month as described in the other answer and then you could simply use a switch to obtain a name.
Example:
switch(month) {
case 0:
your name is January
break;
...
}
P.S. I think months are zero-based but I'm not 100% sure...

how to get any specific date of current year

Hi I was wondering if there was any way using Jav's Date class or and Joda Time classes to get any specific day of this year. For example if I want the date 12/31/2013. The reason why this is a problem is because I am giving a string representation of someone's birthday lets say "12311991" "MMddyyyy" and I want to convert this to be a Date which has month 12 day 31 and year 2013.
Can anyone help me on this?
I am using the DateMidnight Joda time class and I parse the string into a date using Simple Formatter but I was wondering if there was any way to set the year to be a specific year.

Start by converting the String to a Date...
String dateString = "12311991";
SimpleDateFormat sdf = new SimpleDateFormat("MMddyyyy");
Date date = sdf.parse(dateString);
Which results in ....
Tue Dec 31 00:00:00 EST 1991
Next, use Calendar to modify the year
Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.set(Calendar.YEAR, 2013);
date = cal.getTime();
Which results in...
Tue Dec 31 00:00:00 EST 2013

If you want to implement using JodaTime you can do as below. Format using DateTimeFormatter to get DateTime and then with DateTime#withYear(int) method, year can be changed.
String dob = "12311991";
DateTimeFormatter fmt = DateTimeFormat.forPattern("MMddyyyy");
DateTime dt = fmt.parseDateTime(dob).withYear(2013);
System.out.println(dt);

Try using Calendar
set(int year,
int month,
int date)
http://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#set(int, int, int)

Just use SimpleDateFormat (click me to see all format patterns).
String string = "12/31/2013";
Date date = new SimpleDateFormat("dd/mm/yyyy", Locale.ENGLISH).parse(string);
System.out.println(date);

java.time
The other answers are outdated. The old date-time classes, as well as Joda-Time, have been supplanted by the java.time framework built into Java 8 and later.
The LocalDate class truly represents a date-only value without time-of-day and without time zone (lacking in the original date-time classes).
String input = "12311991";
DateTimeFormatter formatter = DateTimeFormatter.forPattern("MMddyyyy");
LocalDate localDate = LocalDate.parse( input , formatter ); // 1991-12-31
LocalDate differentYear = localDate.withYear( 2013 ); // 2013-12-31