validating the date format, add test case, since NumberFormatExceptio…

[Carpe-Wang]

validating the date format, add test case and since NumberFormatException extends IllegalArgumentException, it is only necessary to write IllegalArgumentException.

Purpose

• Throw exception if public GsonBuilder setDateFormat(String pattern) input pattern is invalid.
• NumberFormatException extends llegalArgumentException, it is only necessary to write llegalArgumentException in public class ISO8601Utils

Checklist

• New code follows the Google Java Style Guide
• If necessary, new public API validates arguments, for example rejects null
• New public API has Javadoc
  • Javadoc uses @since $next-version$
    ($next-version$ is a special placeholder which is automatically replaced during release)
• If necessary, new unit tests have been added
  • Assertions in unit tests use Truth, see existing tests
  • No JUnit 3 features are used (such as extending class TestCase)
  • If this pull request fixes a bug, a new test was added for a situation which failed previously and is now fixed
• mvn clean verify javadoc:jar passes without errors

[Carpe-Wang]

Sorry everyone, I make a mistake when I solve conflict. So I close first pr, and make a new pr. I am so sorry for my mistake.

[Marcono1234]

@Carpe-Wang why did you close this PR? I think you can just run mvn spotless:apply, commit and push the changes and it should be fine then.

Sorry though for the trouble; in the meantime while your PR was open checks had been added which verify that the code is properly formatted, which are now causing the build failure.

[Carpe-Wang]

@Carpe-Wang why did you close this PR? I think you can just run mvn spotless:apply, commit and push the changes and it should be fine then.

Sorry though for the trouble; in the meantime while your PR was open checks had been added which verify that the code is properly formatted, which are now causing the build failure.

Because, I thought this submission was fairly straightforward, but it seemed to have been overlooked by the collaborators, so I closed it. I have now reopened it and am reviewing and addressing the areas that may have caused issues.

[Marcono1234]

Thanks!

Technically the current GsonBuilder implementation also allows blank strings as 'no-pattern':

gson/gson/src/main/java/com/google/gson/GsonBuilder.java

Line 889 in bf57258

if (datePattern != null && !datePattern.trim().isEmpty()) {

But I am not sure if that is something we have to keep supporting and if anyone really relies on this (especially since it was not publicly documented).

@eamonnmcmanus, would it make sense to run the changes of this PR against the Google tests to be safe anyway?

Edit: Nevermind new SimpleDateFormat(...) actually considers empty and blanks strings as valid, so it is still possible to use them.

[eamonnmcmanus]

@eamonnmcmanus, would it make sense to run the changes of this PR against the Google tests to be safe anyway?

I've already done that, and it didn't show up any problems.

[eamonnmcmanus]

Thanks for this contribution!

[Carpe-Wang]

Thanks for this contribution!

It's my honor. By the way out of curiosity, what do I need to do to become a contributor to this project? What more effort is required?

[eamonnmcmanus]

By the way out of curiosity, what do I need to do to become a contributor to this project? What more effort is required?

Well, you already are a contributor, since you've just contributed this PR. Perhaps I'm not understanding the question?

[Carpe-Wang]

By the way out of curiosity, what do I need to do to become a contributor to this project? What more effort is required?

Well, you already are a contributor, since you've just contributed this PR. Perhaps I'm not understanding the question?

I mean display in here

[eamonnmcmanus]

I think the people in that box are chosen automatically by GitHub based on who has contributed the most. If you open up where it says "+ 132 contributors" you should see everyone else. I don't see you there yet, but probably it only gets updated every so often.