RFR: 8159055: ImageIcon.setImage can't handle null parameter [v5]

[Alexey Ivanov]

On Mon, 16 Jun 2025 14:59:13 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 one additional commit since the last revision:
> 
>   Fix for constructor

Changes requested by aivanov (Reviewer).

src/java.desktop/share/classes/javax/swing/ImageIcon.java line 224:

> 222:      * @see java.awt.Image#getProperty
> 223:      */
> 224:     public ImageIcon (Image image) {

Does it make sense to expand the javadoc for all the constructors to specify how `null` is handled?

src/java.desktop/share/classes/javax/swing/ImageIcon.java line 380:

> 378:         if (image == null) {
> 379:             return;
> 380:         }

Should `setImage` clear / update the description automatically?

test/jdk/javax/swing/ImageIcon/ImageIconNullImageTest.java line 40:

> 38:         // Setting null image shouldn't cause NPE
> 39:         icon.setImage(null);
> 40:     }

Add the test for `new ImageIcon((Image) null)`: currently it throws `NullPointerException` but it won't throw it after your fix.

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PR Review: https://git.openjdk.org/jdk/pull/25767#pullrequestreview-2932514833
PR Review Comment: https://git.openjdk.org/jdk/pull/25767#discussion_r2150241193
PR Review Comment: https://git.openjdk.org/jdk/pull/25767#discussion_r2150249349
PR Review Comment: https://git.openjdk.org/jdk/pull/25767#discussion_r2150245194