There are several Java virtual machines available today to execute Java

bytecode, both free and commercial products. If executing bytecode in a

virtual machine is undesirable, a developer can also compile Java source

code or bytecode directly to native machine code with tools such as the

GNU Compiler for Java (GCJ). Some processors can execute Java bytecode

natively. Such processors are termed Java processors.

The Java virtual machine provides some support for

dynamically typed languages. Most of the extant JVM instruction set is

statically typed - in the sense that method calls have their signatures

type-checked at compile time, without a mechanism to defer this decision

to run time, or to choose the method dispatch by an alternative

approach.cite-ref-12[12]

JSR 292 (Supporting Dynamically Typed Languages on the Java

Platform)cite-ref-13[13] added a new invokedynamic instruction at the JVM level, to

allow method invocation relying on dynamic type checking (instead of the

extant statically type-checked invokevirtual instruction). The

Da Vinci Machine is a prototype virtual machine implementation that

hosts JVM extensions aimed at supporting dynamic languages. All JVMs

supporting JSE 7 also include the invokedynamic opcode.