PREDEFINED CLASSES

The default Java environment currently consists of several different Java packages implementing a diverse set of fundamental classes. They include the following:
• java.lang
The java.lang package contains the basic java classes and native types: Class, Object, Boolean, Float, Double, Integer, String, and so on plus those dealing with the extended capabilities of the language (e.g. SecurityManager, Thread, and Throwable -- the root class of the Java exception and error hierarchy) and connection with the rest of the system environment.