What\'s the Difference Between System Properties and Environment Variables in JVM?

System Properties vs. Environment Variables in JVM

In the realm of Java programming, understanding the distinction between system properties and environment variables is crucial for managing application configurations. System properties and environment variables serve similar purposes but differ in their nature and accessibility within the Java Virtual Machine (JVM).

System Properties

System properties are configuration settings that are set explicitly within the Java command line using the "-Dpropertyname=value" syntax. These properties can be modified at runtime through methods like System.setProperty() or System.getProperties().load(). System properties provide a way for developers to specify application-specific parameters or modify default JVM settings. To retrieve a system property, you can use System.getProperty(String key) or System.getProperty(String key, String def).

Environment Variables

Environment variables, on the other hand, are defined in the operating system environment. In Linux, they can be set using the "export" command, while in Windows, the "SET" command is used. Unlike system properties, environment variables are not accessible from within the JVM at runtime. They must be defined before the JVM is launched. To retrieve an environment variable, you can use System.getenv(String name).

Key Differences

The primary differences between system properties and environment variables are:

• Mutability: System properties can be modified at runtime, while environment variables cannot.
• Scope: System properties are intended for application-specific configurations, whereas environment variables can be used by multiple processes within the OS.
• Availability: System properties are available within the JVM, while environment variables are not.

Understanding this distinction allows developers to effectively manage application configurations and troubleshoot any issues related to property or variable inaccessibility within their JVM environment.

The above is the detailed content of What\'s the Difference Between System Properties and Environment Variables in JVM?. For more information, please follow other related articles on the PHP Chinese website!