The System L&F is determined at runtime, where the application asks the system to return the name of the appropriate L&F. SystemLookAndFeel-here, the application uses the L&F that is native to the system it is running on.
#Gtk meaning code
It is part of the Java API ( ) and is the default that will be used if you do nothing in your code to set a different L&F.
Most developers never need to interact with the UI delegate directly.
The ComponentUI subclass is referred to by various names in Swing's documentation-"the UI," "component UI," "UI delegate," and "look and feel delegate" are all used to identify the ComponentUI subclass. For example, every JList instance has a concrete implementation of ListUI ( ListUI extends ComponentUI). Swing's architecture enables multiple L&Fs by separating every component into two distinct classes: a JComponent subclass and a corresponding ComponentUI subclass. "Look" refers to the appearance of GUI widgets (more formally, JComponents) and "feel" refers to the way the widgets behave.
The architecture of Swing is designed so that you may change the "look and feel" (L&F) of your application's GUI (seeĪ Swing Architecture Overview).