(to manipulate a dex file) how to disassemble(like dexdump), modify(byte code in text), then assemble to dex again

Question

I want to modify the byte code of ".dex" file in text format, and then assemble the text to dex file again. Have to make sure the final ".apk" is usable.

I want to know some tools rather than make an assembler all by myself.

Answer 1

smali/baksmali is exactly what you want.