import java.io.IOException;
import java.util.Map;

public class EnvSet {
    public static void main(String[] args) {
        ProcessBuilder proc = new ProcessBuilder();
        // Configure to start a new command shell
        // with given command line arguments passed:
        proc.command("cmd", "/c", "start");
        // Modify environment to contain new variables:
        Map<String, String> env = proc.environment();
        env.put("MON", "Meatloaf");
        env.put("TUES", "Taco");
        env.put("WED", "Wienerschnitzel");
        // Run the command, or report an error if it failed
        try {
            proc.start();
        } catch (IOException ex) {
            System.err.println("Error starting cmd:" + ex);
        }
    }
}