java.lang.System Class - The Operating System

JVM Tutorials - Herong's Tutorial Examples

∟java.lang.System Class - The Operating System

This chapter provides tutorial notes and example codes on java.lang.System class. Topics include accessing standard input, output, and error streams; getting the current time in milliseconds and nanoseconds; accessing environment variables; managing JVM instance properties.

What Is java.lang.System

Standard Input, Output, and Error Streams

Current Time in Milliseconds and Nanoseconds

Accessing System Environment Variables

Getting and Adding System Properties

Takeaways:

java.lang.System is a built-in class that represents the operating system.
in, out and err properties provides standard input, output, and error streams.
nanoTime() method returns the current time in nanoseconds.
getenv() method returns all environment variables defined in the operating system.
getProperties() method returns all properties stored at the JVM instance level.