BlueJ is a Java integrated development environment designed for college and university students. It was developed by the University of Kent and Deakin University to teach object orientation in a Java development environment. BlueJ provides an easy-to-use teaching environment that helps first year students learn the Java programming language and then helps transition them to a world IDE (NetBeans). The BlueJ integrated development environment is highly interactive and encourages experimentation and exploration. BlueJ is available for free!
Java + BlueJ: Teach Java technology interactively!