jawa.attributes.code module

class jawa.attributes.code.CodeAttribute(table, name_index=None)

Bases: jawa.attribute.Attribute

A CodeAttribute contains the executable bytecode of a single method.

As a quick example, lets make a “HelloWorld” class with a single method that simply returns when it’s called:

from jawa import ClassFile
from jawa.util.bytecode import Instruction

cf = ClassFile.create('HelloWorld')

main = cf.methods.create(
    # The name of the method
    'main',
    # The signature of the method
    '([Ljava/lang/String;)V',
    # Tell Jawa to automatically create an empty CodeAttribute for
    # us to use.
    code=True
)
main.code.max_locals = 1
main.access_flags.acc_static = True
main.code.assemble([
    Instruction.from_mnemonic('return')
])

# Save it to disk so we can run it with the JVM.
with open('HelloWorld.class', 'wb') as fout:
    cf.save(fout)

ADDED_IN = '1.0.2'

MINIMUM_CLASS_VERSION = (45, 3)

assemble(code)

Assembles an iterable of Instruction objects into a method’s code body.

disassemble(*, transforms=None) → Iterator[jawa.util.bytecode.Instruction]

Disassembles this method, yielding an iterable of Instruction objects.

pack()

The CodeAttribute in packed byte string form.

unpack(info)

Read the CodeAttribute from the byte string info.

Note

Advanced usage only. You will typically never need to call this method as it will be called for you when loading a ClassFile.

Parameters:info – A byte string containing an unparsed CodeAttribute.

class jawa.attributes.code.CodeException(start_pc, end_pc, handler_pc, catch_type)

Bases: tuple

catch_type

Alias for field number 3

end_pc

Alias for field number 1

handler_pc

Alias for field number 2

start_pc

Alias for field number 0