BlueJ is an integrated Java environment specifically designed for introductory teaching. It aims to provide an easy-to-use teaching environment for the Java language that facilitates the teaching of Java to first year students. Special emphasis has been placed on visualization and interaction techniques to create a highly interactive environment that encourages experimentation and exploration. The program boasts the following features: BlueJ is object-oriented In BlueJ students interact with classes and objects. They can manipulate class structure graphically and textually. Objects can be created and methods of any object can be called interactively. BlueJ has been designed for teaching BlueJ offers a unique mix of sophisticated support for visualisation and interaction and a simple and intuitive interface. BlueJ visualises class structure and objects. In BlueJ, class structure can be seen and manipulated on screen, and objects can be interactively created and operations called. BlueJ is free The environment is free of charge.