[warning] "Empty block should be documented" warning for records without parameter

[jubax]

When you have

sealed interface Foo {
    record Bar1WithParameter(String parameter) implements Foo {
    }
    record Bar2WithoutParameter() implements Foo {
    }
    record Bar3WithParameter(String parameter) implements Foo {
    }
}

Then you get the "empty block" warning for the seconds record (probably because the record has no parameters):

This warning should not be shown.

[srikanth-sankaran]

I'll take a look.

I have never programmed with records so a naive question. Does a record with no data make sense ? Are there valid use cases for such ??

[jubax]

I'll take a look.

I have never programmed with records so a naive question. Does a record with no data make sense ? Are there valid use cases for such ??

Yes, it is useful for more functional-style result values. E.g. consider

ParseLogFileResult parseLogFileAndExtractErrorLevelMessages(File file) {}

sealed interface ParseLogFileResult {
  record Success(List<String> messagesWithErrorLevel) implements ParseLogFileResult {}
  record NotApplicable_FileDoesNotExist() {}
  record NotApplicable_InvalidLogFileFormat() {}
  record Failure(Exception exception) {}
}

So we are using records as markers here.

[iloveeclipse]

Oftopic: why not use enums instead?

[jubax]

Oftopic: why not use enums instead?

Because enums are static. But in the example above I want to return the actual values. With the structure above I can write

    sealed interface ParseLogFileResult {
      record Success(List<String> messagesWithErrorLevel) implements ParseLogFileResult {}
      record NotApplicable_FileDoesNotExist() implements ParseLogFileResult {}
      record NotApplicable_InvalidLogFileFormat() implements ParseLogFileResult {}
      record Failure(Exception exception) implements ParseLogFileResult {}
    }

    ParseLogFileResult parseLogFileAndExtractErrorLevelMessages(File file) {
    return new ParseLogFileResult.Success(List.of("a", "b"));
    }

    public void test() {
    ParseLogFileResult result = parseLogFileAndExtractErrorLevelMessages(new File("x.log"));
    switch (result) {
            case ParseLogFileResult.Success(List<String> messagesWithErrorLevel) -> {
                System.out.println(messagesWithErrorLevel);
            }
            case ParseLogFileResult.NotApplicable_FileDoesNotExist() -> {}
            case ParseLogFileResult.NotApplicable_InvalidLogFileFormat() -> {}
            case ParseLogFileResult.Failure(Exception ex) -> { ex.printStackTrace(); }
    }
    }

[srikanth-sankaran]

Thanks for the example. Thought provoking (at least for me.)