Most sophisticated code coverage tool for Java and Groovy.
Best Tools For Java
Browse 8 + Java Tools
OpenCloverFree

Mariana TrenchFree
Mariana Trench is a security focused static analysis platform targeting Android.

SikuliXFree
Automation of GUI components with mouse and keyboard actions.

JubulaFree
Jubula Functional Testing Tool for desktop Java applications

jUnitFree
#Unit Testing

TestNGFree
Java based testing framework

Apache JmeterFree
Open source load testing tool