How to pass java code a parameter from maven for testing

This is the exact thing I was looking for my automation test and I got it working.

Command Line argument

mvn clean test -Denv.USER=UAT -Dgroups=Sniff

My Pom Xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>TestNg</groupId>
    <artifactId>TestNg</artifactId>
    <version>1.0</version>

    <dependencies>
        <dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>6.8</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.12.4</version>
                <configuration>
                    <systemPropertyVariables>
                        <environment>${env.USER}</environment>
                    </systemPropertyVariables>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

TestNG test

import org.testng.annotations.Parameters;
import org.testng.annotations.Test;


public class TestAuthentication {

    @Test (groups = { "Sniff", "Regression" })
    public void validAuthenticationTest(){
        System.out.println(" Sniff + Regression" + System.getProperty("environment"));
    }

    @Test (groups = { "Regression" },parameters = {"environment"})
    public void failedAuthenticationTest(String environment){
        System.out.println("Regression-"+environment);
    }

    @Parameters("environment")
    @Test (groups = { "Sniff"})
    public void newUserAuthenticationTest(String environment){
        System.out.println("Sniff-"+environment);
    }
}

The above works well. Additionally, if you need to use testng.xml, you can specify the suiteXmlFile like …

      <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>2.12.4</version>
            <configuration>
                <systemPropertyVariables>
                    <environment>${env.USER}</environment>
                </systemPropertyVariables>
                <suiteXmlFiles> 
                    <suiteXmlFile>testng.xml</suiteXmlFile>
                </suiteXmlFiles>
            </configuration>
        </plugin>

Also, I prefer using @Parameters instead of parameters in @Test() as the later is deprecated.