Java security model is one of the most interesting and unique aspects of the language. For the main part it''s broken into two pieces: the user changeable security manager that checks various API operations such as file access, and the byte code verifier that asserts the validity of compiled byte code. Public abstract class Security Manager java.lang.Security Manager is an abstract class that different applications subclass to implement a particular security policy. It allows an application to determine if the particular operation will create a security exception.