StreamingWorkbook.getSheet(String) throws exception instead of returning null

[mrotteveel]

The method StreamingWorkbook.getSheet(String) throws a MissingSheetException instead of returning null as specified in Workbook.getSheet(String):

Returns:
Sheet with the name provided or null if it does not exist

[pjfanning]

@mrotteveel to be frank, I'd prefer to fix the javadoc in excel-streaming-reader - in 2021, most developers seem to agree nulls are a bad thing

[mrotteveel]

@mrotteveel to be frank, I'd prefer to fix the javadoc in excel-streaming-reader - in 2021, most developers seem to agree nulls are a bad thing

I understand that sentiment. I do want to point out that will break expectations of people like me who checked the Apache POI API and used that to form assumptions of the behaviour, or implementations that take any Workbook to do their thing.

[pjfanning]

For now, I've gone with correcting the javadoc. I may change the code in a future major release.

[daniel-shuy]

There are a few downsides to this behavior:

• This is very confusing as most of the time people are working with the Workbook interface, so its very misleading when the implementation differs from the interface' s Javadoc.
• When checking if a Sheet with the given name exists, catching Exceptions unnecessarily is expensive, while using getSheetIndex(String) and comparing if the return value is -1 is a little ugly (the behavior of returning -1 if a Sheet is not found is also not documented).
• This prevents StreamingReader from being a drop-in replacement for XSSFWorkbook.

@pjfanning since you are also the maintainer for Apache POI, and Apache POI has migrated to Java 8, maybe Workbook#getSheet(String) can be modified to return an Optional<Sheet> instead? (I understand that this would be a breaking change, maybe this can be done across the board for all getX methods in Apache POI 6.x.x?)