RFR: 8159055: ImageIcon.setImage and ImageIcon(Image) constructor can't handle null parameter [v11]

[Alexey Ivanov]

On Mon, 23 Jun 2025 21:17:05 GMT, ExE Boss <duke at openjdk.org> wrote:

>> src/java.desktop/share/classes/javax/swing/ImageIcon.java line 233:
>> 
>>> 231:         Object o = image.getProperty("comment", imageObserver);
>>> 232:         if (o instanceof String) {
>>> 233:             description = (String) o;
>> 
>> To address [Phil's comment](https://github.com/openjdk/jdk/pull/25767/files#r2155610976):
>> 
>>> This is wasted work if the app calls ImageIcon(Image, String) because that promptly over-writes whatever was obtained via this code.
>> 
>> If we're going to change the constructors, to avoid *this wasted work* when `ImageIcon(Image, String)` constructor is called, I suggest moving the work into `ImageIcon(Image, String)` and implement `ImageIcon` like this:
>> 
>> 
>>     public ImageIcon (Image image) {
>>         String description = null;
>>         if (image != null) {
>>             Object o = image.getProperty("comment", null);
>>             if (o instanceof String) {
>>                 description = (String) o;
>>             }
>>         }
>>         this(image, description);
>> 
>> It is allowed in JDK 22 and later.
>
> Note that this was a preview language feature until **JDK 25**.

I haven't done my due diligence to verify whether this feature can be used. Even if this particular way can't be used, it's still a viable option, just move the code above into a helper method.


    public ImageIcon(Image image, String description) {
        this.image = image;
        this.description = description;

        loadImage(image);
    }

    public ImageIcon (Image image) {
        this(image, getImageComment(image));
    }

    /**
     * {@return the {@code "comment"} property of the image
     * if the value of the property is a sting}
     * @param image the image to get the {@code "comment"}  property
     */
    private static String getImageComment(Image image) {
        if (image == null) {
            return null;
        }

        Object o = image.getProperty("comment", null);
        return (o instanceof String) ? (String) o : null;
    }


This should be done separately from this changeset, I think, to have shorter, more specific changes.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25767#discussion_r2164102520