Provides user interface objects built according to the Java look and feel (once codenamed Metal), which is the default look and feel.
These classes are designed to be used while the corresponding
LookAndFeel class has been installed
(UIManager.setLookAndFeel(new XXXLookAndFeel())).
Using them while a different LookAndFeel is installed may produce
unexpected results, including exceptions. Additionally, changing the
LookAndFeel maintained by the UIManager without updating the
corresponding ComponentUI of any JComponents may also produce
unexpected results, such as the wrong colors showing up, and is generally not
encouraged.
Note: Most of the Swing API is not thread safe. For details, see Concurrency in Swing, a section in The Java Tutorial.