1 Software Development Kits

The Java Software Development Kit (SDK) is available for free from Sun Microsystems (the creators of Java).

An open-source implementation of Java is also available for those who are interested.

2 APIs and Libraries

There are a number of free APIs and libraries for Java available, including:

3 Integrated Development Environments

There are some very good free Integrated Development Environments (IDEs) IDEs available, including:

4 Verification, Testing and Debugging

There are a variety of verification, testing and debugging tools available, that are "standalone" and/or integrate with an IDE, including:

5 Monitoring and Profiling

The Java VisualVM provides detailed information about Java applications while they are running

6 GUI Layout Tools

Sophisticated GUI layout can be somewhat tedious. However, if you're willing to use absolute layout there are some tools available, including: