Java - how to get single system environment variable value by name?

import java.util.Map;

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public class JavaGetSingleEnvironmentVariablesExample {

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    public static void main(String[] args) {

        Map<String, String> env = System.getenv();

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        String os = env.get("OS");

        System.out.println(os); // Windows_NT

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        String username = env.get("USERNAME");

        System.out.println(username); // seth

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        String numberOfProcessors = env.get("NUMBER_OF_PROCESSORS");

        System.out.println(numberOfProcessors); // 4

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        String path = env.get("Path");

        // C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Wind ....

        System.out.println(path);

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        String windir = env.get("windir");

        System.out.println(windir); // C:\Windows

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        String processorArchitecture = env.get("PROCESSOR_ARCHITECTURE");

        System.out.println(processorArchitecture); // AMD64

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        String systemDrive = env.get("SystemDrive");

        System.out.println(systemDrive); // C:

    }

}

Windows_NT

seth

4

C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Wind ....

C:\Windows

AMD64

C: