Cobertura is test code coverage tool. It’s free and it does job well. I tried it with projects compiled with Ant. There a few good tuts on web how to do it. And I tried it with maven. It’s even easier, you just need to put a simple entry into your pom.xml file. Something like

    <reporting>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>cobertura-maven-plugin</artifactId>
                <version>2.4</version>
            </plugin>
        </plugins>
    </reporting>

And there is a worth tip to remember (because I had problem with cobertura it simply didn’t count and raport, coverage was always zero)
Uncheck option for maven “skip test ” in your favorite IDE – mine is netbeans. (For developing without testing as I did I’ve turned it off. Then I wrote junits and was firing test by hand without unchecking the box)