Platform Environment

Properties
Properties are configuration values manages as key/value pairs. In each pair, the key and value are both String values. To manage properties, create instances of java.util.Properties. Properties extends java.util.Hashtable

Quering Environment Variables
On the Java platform, an application uses System.getEnv to retrieve environment varibale values. Without an argument, getEnv returns a read-only instance of java.util.Map.

Passing Environment Variables to new process
Environment variables can be passed to a new process by passing it to a Process Builder object

System Properties
The System class maintains a Properties object that describes the configuration of the current working environment. The system properties can be read and written as well

The Security ManageA security manager object can be defined on every application to have a security policy. If any action or event not allowed by security policy is performed, then the Security Exception is thrown.