Execute System Commands

I want to Execute System Commands like dos commands within my program in jave
like ShellExecute function in C++

Every Java application has a single instance of class
java.lang.Runtime that allows the application to interface with
the environment in which the application is running. The current
runtime can be obtained from the getRuntime method. An application
cannot create its own instance of this class. For executing
windows apps use

Runtime.getRuntime().exec( "cmd.exe /c start
NOTEPAD.EXE"); //open notepad