RFR: 8283214: [macos] Screen magnifier does not show the magnified text for JcomboBox [v2]

[Nikita Provotorov]

On Mon, 19 Jun 2023 08:56:04 GMT, Abhishek Kumar <abhiscxk at openjdk.org> wrote:

>> src/java.desktop/share/classes/javax/swing/plaf/basic/BasicComboBoxUI.java line 1121:
>> 
>>> 1119:     @Override
>>> 1120:     public int getAccessibleChildrenCount(JComponent c) {
>>> 1121:         return 2;
>> 
>> I think the logic here has to be equal to the logic in `getAccessibleChild `, otherwise `getAccessibleChildrenCount` returns 2 even when `getAccessibleChild(..., 1)` returns null.
>
> Can you please elaborate more or what logic can be added here?

I mean `getAccessibleChild(..., 1)` can still return null (when both `if`s of `case 1` resolve to false). Let's consider the following code:

public void doSmthWith(JComponent component, BasicComboBoxUI ui) {
    if (ui.getAccessibleChildrenCount(component) > 1) {
        // well, we have at least 2 components, so we can expect to get a valid object below
        final var ac = ui.getAccessibleChild(component, 1)
                                  .getAccessibleContext(); // <= possible NPE
        // ...
    }
}


I think we have to return 1 from `getAccessibleChildrenCount(...)` for the cases when `getAccessibleChild(..., 1)` returns `null`

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PR Review Comment: https://git.openjdk.org/jdk/pull/14497#discussion_r1233996986