Java System.getenv() – Syntax & Examples

Java System.getenv() – Examples

In this tutorial, we will learn about the Java System.getenv() function, and learn how to use this function to get all environment variables or value for a specific environment variable, with the help of examples.

getenv()

System.getenv() returns an unmodifiable string map view of the current system environment.

Syntax

The syntax of getenv() function is

getenv()

Returns

The function returns Map<String,String> object.

Example 1 – getenv()

In this example, we will get the Map view of System Environment and print all these mappings.

Java Program

import java.util.Map;

public class Example {
	public static void main(String[] args) { 
		Map<String, String> env  = System.getenv(); 

		for (String envName : env.keySet()) { 
			System.out.format("%s = %s%n", envName, env.get(envName)); 
		} 
	} 

}

Output

USERDOMAIN_ROAMINGPROFILE = DESKTOP-QRVE3I1
PROCESSOR_LEVEL = 6
SESSIONNAME = Console
ALLUSERSPROFILE = C:\ProgramData
PROCESSOR_ARCHITECTURE = AMD64
PSModulePath = C:\Program Files\WindowsPowerShell\Modules;C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules
SystemDrive = C:
USERNAME = TutorialKart
ProgramFiles(x86) = C:\Program Files (x86)
FPS_BROWSER_USER_PROFILE_STRING = Default
PATHEXT = .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
COMPOSE_CONVERT_WINDOWS_PATHS = true
DriverData = C:\Windows\System32\Drivers\DriverData
IntelliJ IDEA Community Edition = C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.1\bin;
ProgramData = C:\ProgramData

Based on the environment variables set in your PC, the output may change.

getenv(String name)

System.getenv(name) gets the value of the specified environment variable name.

System.getenv(), without any argument passed to it, returns a map of all the environment variables. But, if you pass a specific key to this getenv() method, it returns the value corresponding to that environment variable.

Syntax

The syntax of getenv(name) function is

getenv(String name)

where

Parameter	Description
name	The name of environment variable.

Returns

The function returns String object.

Example 2 – getenv(String name)

In this example, we will get the specific environment variables like TEMP, OS, JAVA_HOME, USERNAME, PROCESSOR_ARCHITECTURE, etc., using System.getenv(name) method.

Java Program

public class Example {
	public static void main(String[] args) { 
        System.out.println(System.getenv("TEMP")); 
        System.out.println(System.getenv("OS")); 
        System.out.println(System.getenv("JAVA_HOME"));
        System.out.println(System.getenv("USERNAME"));
        System.out.println(System.getenv("PROCESSOR_ARCHITECTURE"));
	} 
}

Output

C:\Users\TutorialKart\AppData\Local\Temp
Windows_NT
C:\Program Files\Java\jdk1.8.0_201
TutorialKart
AMD64

Conclusion

In this Java Tutorial, we have learnt the syntax of Java System.getenv() function, and also learnt how to use this function with the help of examples.