His departure follows Sun's decision to offer Java as open source.

James Gosling, inventor of the Java language and also a Sun vice president, will take on Hamilton's responsibilities, Sun said.

Sun would not say why Hamilton left.

"Sun thanks Graham for his many contributions to the company and to Java technology. Graham is widely respected by Sun employees and developers around the world. While it is always sad to see an employee of his caliber depart, we wish him well in all his future endeavors," the company said.