The Java Virtual Machine (shortened JVM , in French virtual Machine Java ) is a virtual Machine making it possible to interpret and carry out the Bytecode Java.

This program is specific to each Plate-forme or couples (Machine/Operating system) and allows the applications Java compiled in bytecode to produce the same results whatever the platform, as long as this one is provided with the virtual machine adequate Java.

The most used virtual machine is that of Sun Microsystems. It is free, owner to version 6 (stable) and free starting from version 7 (not yet official).

November 11th, 2006, Sun Microsystems published the sources of its virtual machine HotSpot and its compiler javac under license Open Source LPG.

Sometimes the virtual machines developed by the other editors can present compatibility issues according to their compliance with the specifications provided by Sun. Moreover, it is rare that they are up to date compared to last the version of Sun.

• That of Microsoft was provided with the operating system Windows. But Sun was denied this virtual machine which they distributed, Sun thought that the machine could be " bugguée" to voluntarily counter the projection of the language java (compatibility on OS = risk of loss for Microsoft). Following a lawsuit gained by Sun, it is not it any more.
• Apple created some for its Mac OS.
• That of IBM seems to be a good alternative to that of Sun, it is available for the platforms AIX, Z/OS, GNU/Linux and Windows. It is often used with EDI Eclipse.
• There exist also virtual machines under license LPG or LGPL like Kaffe or SableVM. The project GNU includes a " in addition; under-projet" of virtual machine Java named GNU Classpath.

External bonds

• Specifications of the JVM
• GNU Classpath
• Explanations on Garbage Collector
• To include/understand the binary Java