RFR: 8159055: Clarify handling of null and invalid image data for ImageIcon constructors and setImage method [v24]

[Phil Race]

On Tue, 29 Jul 2025 14:13:39 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

>> When trying to call 'icon.setImage(null);' where 'icon' is an instance of ImageIcon, a null pointer exception is thrown at runtime.
>> The code tried to get the `id` for that image and instantiates `MediaTracker` to associate the null image to that `id` and checks the status of loading this null image, removes the null image from the tracker and then tries to get the image width where it throws NPE as image is null.
>> 
>> It's better to not go through all MediaTracker usage and bail out initially itself for null image..
>
> Prasanta Sadhukhan has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - Modify summary
>  - Modify summary
>  - Remove redundant fileName param

> 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 type of JDK-8159055 should be changed to _bug_.

I agree. Not saying how null is handled is a bug. So fixing it is a bug fix, not an enhancement.

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PR Comment: https://git.openjdk.org/jdk/pull/25767#issuecomment-3133333056