I am trying to use FlatLaf theme in my OSGI services. Currently calling FlatDarkLaf.setup() in the first service that initializing. It is working perfectly fine in the same service but outside of that, some swing components could not find UI Classes as example below.
java.lang.Error: no ComponentUI class for: javax.swing.JOptionPane[,0,0,0x0,invalid,alignmentX=0.0,alignmentY=0.0,border=,flags=0,maximumSize=,minimumSize=,preferredSize=,icon=,initialValue=,message=com.ekinokssoftware.kabintester.common.AddTakePanel[,0,0,0x0,invalid,layout=java.awt.GridBagLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=9,maximumSize=,minimumSize=,preferredSize=],messageType=QUESTION_MESSAGE,optionType=YES_NO_CANCEL_OPTION,wantsInput=false]
at java.desktop/javax.swing.UIDefaults.getUIError(UIDefaults.java:763)
at java.desktop/javax.swing.MultiUIDefaults.getUIError(MultiUIDefaults.java:144)
at java.desktop/javax.swing.UIDefaults.getUI(UIDefaults.java:793)
at java.desktop/javax.swing.UIManager.getUI(UIManager.java:1072)
at java.desktop/javax.swing.JOptionPane.updateUI(JOptionPane.java:1880)
at java.desktop/javax.swing.JOptionPane.<init>(JOptionPane.java:1845)
at java.desktop/javax.swing.JOptionPane.showOptionDialog(JOptionPane.java:869)
at java.desktop/javax.swing.JOptionPane.showConfirmDialog(JOptionPane.java:806)
at java.desktop/javax.swing.JOptionPane.showConfirmDialog(JOptionPane.java:768)
at java.desktop/javax.swing.JOptionPane.showConfirmDialog(JOptionPane.java:729)
at java.desktop/javax.swing.JOptionPane.showConfirmDialog(JOptionPane.java:700)
I am suspecting this is some kind of ClassLoader problem but don't know how to approach since there are no information about FlatLaf with OSGI. Calling FlatDarkLaf.setup() in each service also didn't help.
Facing the same problem in our OSGI environment, I found the following article explaining that the ClassLoader problem can be solved by specifiying a corresponding ClassLoader property in the LookAndFee defaults. So, specifying:
UIManager.getLookAndFeelDefaults().put("ClassLoader", MyLookAndFeelManager.class.getClassLoader());
after switching to FlatLaf solved our problems for the usage of that LookAndFeel. As a nice and very welcome side effect, we have only a single OSGI-Bundle that depends on the FlatLaf jar files.