Java | Java script | Java compiler

The compiler used in compiling java programming language is called a Java compiler. The most common form of output from a Java compiler is Java class files containing platform-neutral Java bytecode. There are also compilers emitting optimized native machine code for a particular hardware/operating system combination. Most Java-to-bytecode compilers do virtually no optimization, leaving this until run time to be done by the JRE.
The very first Java compiler developed by Sun Microsystems was written in C using some libraries from C++. The Java Virtual Machine [JVM] loads the class files and either interprets the bytecode or just-in-time compiles it to machine code and then possibly optimizes it using dynamic compilation.