help for decompilation file

hi!

i’ve a .class file originally compiled from relative .java source file

over the years the source file has been lost

how to can decompile from .class file to original .java source file?!?

all tools for decompiling .class file have failed

because maybe the source/compiled file it is slightly different from the standard java/class format

source 1 - sample source:

compiled 1 - relative compiled of previous sample source:

compiled 2 - compiled file w/o source, but originally compiled from relative source w/ same mechanism (by same application):

is there any way to do decompile it?

thx!