Java Bytecode - Generation

Generation

The most common language targeting Java Virtual Machine by producing Java bytecode is Java. Originally only one compiler existed, the javac compiler from Sun Microsystems, which compiles Java source code to Java bytecode; but because all the specifications for Java bytecode are now available, other parties have supplied compilers that produce Java bytecode. Examples of other compilers include:

• Jikes, compiles from Java to Java bytecode (developed by IBM, implemented in C++)
• Espresso, compiles from Java to Java bytecode (Java 1.0 only)
• GCJ, the GNU Compiler for Java, compiles from Java to Java bytecode; it is also able to compile to native machine code and is available as part of the GNU Compiler Collection (GCC).

Some projects provide Java assemblers to enable writing Java bytecode by hand. Assembly code may be also generated by machine, for example by compiler targeting Java virtual machine. Notable Java assemblers include:

• Jasmin, takes textual descriptions for Java classes, written in a simple assembly-like syntax using Java Virtual Machine instruction set and generates a Java class file
• Jamaica, a macro assembly language for the Java virtual machine. Java syntax is used for class or interface definition. Method bodies are specified using bytecode instructions.

Others have developed compilers, for different programming languages, in order to target the Java virtual machine, such as:

• JRuby and Jython, two scripting languages based on Ruby and Python
• Groovy, a scripting language based on Java
• Scala, a type-safe general-purpose programming language supporting object-oriented and functional programming
• JGNAT and AppletMagic, compile from the Ada programming language to Java bytecode
• C to Java byte-code compilers
• Clojure
• MIDletPascal
• JavaFX Script code is also compiled to Java bytecode.