JSR-310 - Migrate from joda-time to java.time

[yeikel]

From the https://www.joda.org/joda-time/ website

The standard date and time classes prior to Java SE 8 are poor. By tackling this problem head-on, Joda-Time became the de facto standard date and time library for Java prior to Java SE 8. Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.

[yeikel]

I will be running this migrational manually internally soon, and I will add some examples as I find them

Would it make sense to create individual issues for them?

[timtebeek]

Appreciate you reporting those proposals for recipes here! I think we can start with a GitHub task list initially, as I imagine some will the too small to really warrant a separate pull request. Hope it's easy enough to maybe even tackle a few, as I imagine you'll be looking for a mix of manual and automated changes to complete this migration.

[michael-schnell]

I'm currently trying to implement a first recipe for this. It works so far, but removing the old import fails.

Seems as if the following line does not work:

maybeRemoveImport("org.joda.time.format.DateTimeFormatterBuilder");

Full recipe class:

public class ReplaceJodaAppendSecondofDayRecipe extends Recipe {

    private static final MethodMatcher APPEND_SECOND_OF_DAY_INT =
            new MethodMatcher("org.joda.time.format.DateTimeFormatterBuilder appendSecondOfDay(int)");

    @Override
    public String getDisplayName() {
        return "Replace Joda 'DateTimeFormatterBuilder.appendSecondOfDay(int)'";
    }

    @Override
    public String getDescription() {
        return "Replaces the method call 'org.joda.time.format.DateTimeFormatterBuilder#appendSecondOfDay(int)' with "
                + "'java.time.format.DateTimeFormatterBuilder#appendValue(ChronoField, int)'.";
    }

    @Override
    public Set<String> getTags() {
        return Collections.singleton("JODA");
    }

    @Override
    public Duration getEstimatedEffortPerOccurrence() {
        return Duration.ofMinutes(5);
    }

    @Override
    public TreeVisitor<?, ExecutionContext> getVisitor() {
        return Preconditions.check(new NoMissingTypes(), new JavaIsoVisitor<ExecutionContext>() {

            private final JavaTemplate newAppendValue =
                    JavaTemplate.builder("#{any()}.appendValue(ChronoField.SECOND_OF_DAY, #{any(int)})")
                            .imports("java.time.temporal.ChronoField").build();

            @Override
            public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method,
                                                            ExecutionContext executionContext) {
                if (APPEND_SECOND_OF_DAY_INT.matches(method)) {
                    method = newAppendValue.apply(getCursor(), method.getCoordinates().replace(), method.getSelect(),
                            method.getArguments().get(0));
                    maybeRemoveImport("org.joda.time.format.DateTimeFormatterBuilder");
                    maybeAddImport("java.time.format.DateTimeFormatterBuilder", false);
                    maybeAddImport("java.time.temporal.ChronoField");
                    return method;
                }
                return super.visitMethodInvocation(method, executionContext);
            }

        });
    }

}

Any idea what's wrong?

[timtebeek]

Great to see you got started on this @michael-schnell ! Much appreciated; I don't immediately see a what's wrong yet, but feel free to open up a draft pull request, as that's a little easier to checkout locally and provide feedback and fixes on.

[michael-schnell]

I think doing the whole Joda part will be >100 recipes as there are many things to migrate for Joda to Java Time.

I think I will open a bug issue with code & test - Then this can be figured out separately.

[timtebeek]

I think doing the whole Joda part will be >100 recipes as there are many things to migrate for Joda to Java Time.

I think I will open a bug issue with code & test - Then this can be figured out separately.

Looking forward to it, thanks!

[michael-schnell]

OK, here it is: https://github.com/openrewrite/rewrite-migrate-java/issues/262 - I created a demo project that is linked in the issue. Should be easy to check out and run the tests.

[timtebeek]

Great! Linking the recipe back here so we know where to pick off from next: https://github.com/michael-schnell/openrewrite-issue/pull/1

[timtebeek]

@michael-schnell Did you end up developing more recipes to aid the migration away from Joda time? If there's anything you can share that would be much appreciated!

[michael-schnell]

Unfortunately not. We ended up in a big manual migration for the ~20 projects. Especially tricky topics were:

• Different "null" handling in several functions between Joda and Java Time
• 6 digit milliseconds in Java Time vs 3 digits in Joda (Could also be a problem for JPQL/SQL queries that try to find old data in the DB that were written with Joda and now read by Java Time).
• Converter configuration for JAX-B in XML config files
• Code generator configuration in Maven pom.xml files (plugins)
• Some silly functions in Joda that accept values that are no longer valid in Java Time (like calculating a diff with "begin"/"end" and Joda accepts "null" for one of the values interpreted as "now" where Java Time does not)
• Missing functions in Java Time that were available in Joda (see https://www.threeten.org/threeten-extra/)
• Handling (calculation) of the time zone, which is quite different in Joda and Java Time
• Choosing the right replacement for Joda "DateTime" (OffsetDateTime, ZonedDateTime or sometines even LocalDateTime in Java Time)

[timtebeek]

Thanks for the detailed report! Really helps to have as list of things to look out for. Clearly not an easy one to one replacement. :/

[timtebeek]

With the addition of a first batch of Joda time related recipes I propose we close this catch all issue, and then potentially open new individual issues (or PRs) for cases not yet covered, such that it's easier to track demand and progress.

• https://github.com/openrewrite/rewrite-migrate-java/pull/567

Thanks all!