import java.util.Map;
 
public class Getenv{
    public static void main(String args[]){
        for (Map.Entry<String, String> env : System.getenv().entrySet()) {
            System.out.println(env.getKey() + " : " + env.getValue());
        }
    }
}

import org.apache.commons.lang.builder.ToStringBuilder;
 
public class VarDump{
    public static void main(String args[]){
        System.out.println(ToStringBuilder.reflectionToString(args));
    }
}

hoge=fuga
hello=world