System Class (Top)

The java.lang.System class implements operations that can examine and manipulate system information in a platform independent manner. This class can not be instantiated.

Runtime Class (Top)

The java.lang.Runtime class implements operations for system functions such as loading libraries, executing programs, and performing garbage collection. This class can not be instantiated. The System class provides shortcuts to many of the operations in this class. For example, the System.exit() operation invokes the Runtime.exit() operation.