Explain open source Java.
On November 13, 2006, Sun released much of Java as free and open source software, (FOSS), under the terms of the GNU General Public License (GPL). On May 8, 2007, Sun finished the process, making all of Java’s core code available under free software/open-source distribution terms, aside from a small portion of code to which Sun did not hold the copyright.
OpenJDK (Open Java Development Kit) is a free and open source implementation of the Java programming language. It is the result of an effort Sun Microsystems began in 2006. The implementation is licensed under the GNU General Public License (GNU GPL) with a linking exception.
Why there are still people who say that Java is not open source or free as in free speech?
Am I missing something?
Is Java still proprietary?
Regarding the open source Java - the problem is that in order to call something "Java" you need to get it certified as compliant to the Java spec.
One of the prerequisites of getting this certification is running your JVM through a test suite - Java Technology Compatibility Kit (TCK). This test suite is NOT open sourced.
So you can build a JVM that behaves in a very Java-like way and be completely open source, but, if you want to call it a "Java JVM" you need to buy the certification suite under a non open source license. To many open source advocates this is a complete non-starter.