Java Bytecode: Lesson 2

Each of the Java bytecodes fall into a few categories, here they are, along with examples:

• Loading and Storing (aload_0, astore_0)


• Logic and Arithmetic (dcmpg, iadd)


• Type Conversion (i2d)


• Object Creation and Manipulation (new, putfield)


• Stack Management (swap)


• Control Transfer (goto)


• Method Invoking and Returning (invokestatic, areturn)


• And of course, nothing (nop)

Most bytecodes are also prefixed by the initial object type:

• Integer (i)


• Long (l)


• Short (s)


• Byte (b)


• Character (c)


• Float (f)


• Double (d)


• Reference (a)

- Wikipedia article on Java bytecode.

For further information on each specific bytecode, you can look at this Wikipedia article.

Next time I will dissect the bytecode of such a simple program in any language, the "Hello world" example.