Scala / Java-解析只有日期部分的字符串

Question

So I have 2 strings

val a : String = "foo April 06 1994 bar"
val b : String = "April 06 1994" // this format can change

and I have a seq of 4 parsers

private val dateParsers = Seq(
    JChronicDateParser,
    UKDateParser,
    USDateParser,
    GermanDateParser
  )

and now I parse them variables I get succesful results in both cases

dateParsers.map(parsers => {
            parsers.parse(variable)//a or b
          })

Is there any efficient way to fail the parsing of the string a , I want parsers to fail when there's any extra info or characters in the string with the date part?

I have tried methods like not using any parser rather getting the string in and formatting it with

val dateFormat = new SimpleDateFormat("yyyy-MM-dd")
dateFormat.parse(a) // it fails in both cases so no good

Answer 1

Your SimpleDateFormat fails because the format you give it is wrong. Try "MMMM dd yyyy" .

Also, SimpleDateFormat isn't a very good option. Since java 8, it's better to use DateTimeFormatter instead:

DateTimeFormatter.ofPattern("MMMM dd yyyy").parse("April 06 1994")

As to your other question - "Is there any efficient way to fail the parsing of the string a" - I have no idea what you are asking ... Throw exception? Return an Option ? a Try ?