RFR: 6616245: NullPointerException when using JFileChooser with a custom FileView [v2]

[Alexey Ivanov]

On Mon, 3 Oct 2022 11:42:36 GMT, Tejesh R <tr at openjdk.org> wrote:

>> Why is it bad to modify `JFileChooser` class itself?
>> 
>> I think setting the current directory to `null` while it displays a directory kind of breaks the invariant.
>> 
>> `JFileChooser` navigated to a directory and the current directory is set to it. You tried navigating to another directory, `FileSystem` didn't allow the navigation, so `JFileChooser` continues to display the files in the directory that is showed before. Thus, the current directory hasn't changed. From this point of view, the current directory should remain unchanged.
>
> https://github.com/openjdk/jdk/blob/ccc1d3169691d066c08e294f5d989b007bfab114/src/java.desktop/share/classes/javax/swing/JFileChooser.java#L608
> Here the above logic checks if the current selected directory is traversable and if not it goes up to parent directory till top level and when every check fails then null is set to `currentDirectory`. Should we think of modifying this logic to not to set to null, rather remain in previously valid folder......?

Well, the logic there tries to prevent the current directory from becoming `null`. Yet it traverses up the tree:
https://github.com/openjdk/jdk/blob/ccc1d3169691d066c08e294f5d989b007bfab114/src/java.desktop/share/classes/javax/swing/JFileChooser.java#L603-L607

Probably, if `dir` becomes `null` in the end, it should resort to its default behaviour: `getFileSystemView().getDefaultDirectory()`. Or not change at all?

Then, you can handle the situation here: if `getFileChooser().getCurrentDirectory()` returns `null`, restore the previous current directory.

And what about other L&F? If the same code runs in Windows L&F, Nimbus L&F, any other?

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PR: https://git.openjdk.org/jdk/pull/10485