Java compiler Java program is compiled into binary code can be identified by a virtual machine, such code called a byte code (Bytecode). Bytecode virtual machine is the machine instructions, it has nothing to do with the platform, a unified format, not dependent on specific hardware environment, it runs only on the JVM. JVM byte code, when executed, the bytecode interpreter into specific machine instructions executed.
Java bytecode programs can be obtained through the interpreter, the generated bytecode designed and optimized to improve the operating speed. The current version of Java has the added function of time compiler (just-in-time compiler, referred JIT compiler), the compiler byte code to native machine code, and can be performed at higher speed, so that the efficiency greatly improved, basically reached the level compiled language.