Java Swing tutorials.
Methods which are present at ComponentUI use JComponent object, as a parameter. UI delegate’s stateless implementation is enabled by this convention. Implementation of stateless UI delegate permits one instance of UI delegate, to get used for component class’s instances. This would be reducing no. of objects that get instantiated.
Suck kind of approach is for various simple GUI components. However, in case of more complexed components, it is not considered as “win” as inefficiency is created