Non-Instruction Nodes

Perhaps unintuitively, the first nodes that we are going to cover do not contain any instructions. These are one of three: Line Numbers, Frame Changes and Labels. You needn't concern yourself with the first two: line numbers provide the information used to print linenumbers in stacktraces, and frame changes signal a stackframe change. The ones that are actually interesting to you are labels.

Labels, by themselves, do nothing: their purpose is to mark a location in the bytecode by giving it a name. Although labels generated by the compiler will generally be unintelligible to you (i.e. "L11"), you can actually name your labels whatever you want. What purpose do they serve? They can be combined with Jump Nodes (see the next chapter) to provide control flow.

In the ASM library, you're looking for the class LabelNode.