So much of scientific and engineering software is written in Fortran, C/C++, Python and other languages, that the thought may occur to you: "Why Java?" The answer is simple. Java has many advantages when modeling complex science:

• Java is a "clean" and well-supported object-oriented language; it is simpler than C++, but just as powerful; an object-oriented approach is often the best way to handle the inherent complexity of physical systems
  
  
• Java is Internet-friendly, simplifying the creation of distributed applications necessary for processing large problems and collaborating with colleagues
  
  
• Java is cross-platform, enabling our software to run on anything from multithreaded supercomputers to garden variety desktop and notebook machines
  
  
• Java has a huge amount of built-in functionality and a large collection of optional extensions, permitting focus on the science at hand instead of reinventing the wheel
  
  
• Java performance is on par with compiled languages; recent progress in dynamic optimization and ever-faster virtual machines minimize the performance gap
  
  
• Java is safe; its built-in security mechanisms allow safe network delivery
  
  
• Java simplifies enterprise interoperability, database connectivity and legacy system integration with a support for technologies such as web services, CORBA, LDAP, and Enterprise Java Beans, JDBC and providing an interface to native libraries (JNI)

For example, NASA is using Java as a low-cost and easy-to-use option for controlling Spirit, the robotic rover currently exploring the surface of Mars.

For more information, read The Java Language: An Overview.