NPE in version 2.5 on Windows

[ptorngren]

After upgrading to FlatLaf 2.5, we get a NullPointerException when launching on Windows 10 and 11 (runs OK on macOS, and also on Windows in version 2.4).

Error is stable (happens every time during startup), but it is hard to pinpoint the cause and create a simple test class.

Stacktrace:
java.lang.NullPointerException: Cannot read field "preferred" because "this.xTotal" is null at java.desktop/javax.swing.BoxLayout.preferredLayoutSize(BoxLayout.java:294) at java.desktop/java.awt.Container.preferredSize(Container.java:1826) at java.desktop/java.awt.Container.getPreferredSize(Container.java:1810) at java.desktop/javax.swing.JComponent.getPreferredSize(JComponent.java:1727) at java.desktop/java.awt.BorderLayout.preferredLayoutSize(BorderLayout.java:719) at java.desktop/java.awt.Container.preferredSize(Container.java:1826) at java.desktop/java.awt.Container.getPreferredSize(Container.java:1810) at java.desktop/javax.swing.JComponent.getPreferredSize(JComponent.java:1727) at com.formdev.flatlaf.ui.FlatRootPaneUI$FlatRootLayout.layoutContainer(FlatRootPaneUI.java:444) at java.desktop/java.awt.Container.layout(Container.java:1541) at java.desktop/java.awt.Container.doLayout(Container.java:1530) at java.desktop/java.awt.Container.validateTree(Container.java:1725) at java.desktop/java.awt.Container.validateTree(Container.java:1734) at java.desktop/java.awt.Container.validate(Container.java:1660) at java.desktop/java.awt.Container.validateUnconditionally(Container.java:1697) at java.desktop/java.awt.Window.show(Window.java:1055) at java.desktop/java.awt.Component.show(Component.java:1728) at java.desktop/java.awt.Component.setVisible(Component.java:1675) at java.desktop/java.awt.Window.setVisible(Window.java:1036)

[DevCharly]

Not sure what change in 2.5 causes the issue. I'll have a look...

Could be a threading issue.
Do you invoke Window.setVisible() on the main thread?
Or on the AWT thread?

Make sure to use SwingUtilities.invokeLater()

Recommended way:

public static void main( String[] args ) {
    SwingUtilities.invokeLater( () -> {
        FlatLightLaf.setup();
        JFrame frame = ...
        ...
        frame.setVisible(true);
    } );
}

[ptorngren]

We launch using SwingUtilities.invokeLater(), it's running on the AWT thread.

[DevCharly]

Found the problem, which was caused by a NPE in FlatMenuItemRenderer.getTopLevelFont() when using JideMenu.

Fixed in latest 2.6-SNAPSHOT: https://github.com/JFormDesigner/FlatLaf#snapshots

Please give it a try.
If it fixes the issue in your app, I'll release FlatLaf 2.6 in a few days.

[ptorngren]

Yes, works fine!

[DevCharly]

Great.

FlatLaf 2.6 is now available 😄