RFR: 8159055: ImageIcon.setImage can't handle null parameter [v22]

[Alexey Ivanov]

On Mon, 28 Jul 2025 20:53:23 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

> Currently, [JDK-8159055](https://bugs.openjdk.org/browse/JDK-8159055) is an enhancement which made sense while the goal of this PR was to change `Image.setImage` so that it accepts `null` as parameter.
> 
> After a month of discussions, that solution has been abandoned, instead it is stated that `Image.setImage` will throw `NullPointerException` if `image` parameter is `null`.

I think the proposed fix to accept `null` for `Image.setImage` should've been accepted, specifically https://github.com/openjdk/jdk/compare/master...340254ecceab48f5a0037b32e477a0e168ab2779

Then for documenting handling `null` and invalid parameters, a new bug should've been created, as per [this discussion](https://github.com/openjdk/jdk/pull/25767#issuecomment-3063379284):

> This class is a bit of a mess of accidental behaviours and scant documentation.
>
> Let's document all the NPE behaviours and include a test that verifies it.
> 
> And invalid data like "new byte[0]" or null for a file name, or pointing to something that isn't an image file, or an invalid URL .. etc .. results in an Image instance being present, but it will never be completed so can never be drawn.

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PR Comment: https://git.openjdk.org/jdk/pull/25767#issuecomment-3129978878