RFR: 6450193: After the first Serialization, JTableHeader does not uninstall its UI

[lawrence.andrews]

On Thu, 31 Aug 2023 08:02:35 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

> After the first time a JTableHeader is serialized, it no longer will uninstall its UI upon subsequent serializations.
> This happens for classes that use the BasicTableHeaderUI class. Any LAF that extends the BasicTableHeaderUI like SynthTableHeaderUI and WindowsTableHeaderUI will get an NotSerializableException thrown
> 
> Each time an JComponent instance is Serialized, a [counter ](https://github.com/openjdk/jdk/blob/218829e0a2a3ae5599b81733df53557966392033/src/java.desktop/share/classes/javax/swing/JComponent.java#L5644-L5645) for the instance is incremented. It is de-incremented in JComponent's writeObject or a class that implements it the same way, like JButton, JScrollPane etc..
> With JTableHeader it does not deincrement the counter. The uninstall mechanism will not uninstall a UI if the counter is not 0 on the first pass..It is not possible to call JComponent.setWriteObjectCounter in JTableHeader as it is not in the same package so the fix is to remove the writeObject implementation and rely on JComponent writeObject implementation to make sure uninstallation of UI happens and also NotSerializableException does not happen for Synth

test/jdk/javax/swing/JTableHeader/SerializeJTableHeader.java line 47:

> 45:                 ByteArrayOutputStream baos = new ByteArrayOutputStream();
> 46:                 ObjectOutputStream oos = new ObjectOutputStream(baos);
> 47:                 //System.out.println(jth.getUI());

This line can be removed

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PR Review Comment: https://git.openjdk.org/jdk/pull/15507#discussion_r1311848670