In case there is any doubt, Joesph K and Franz Kafka are interchangeable. Franz was named after Franz Joseph, Emperor of the Austro-Hungarian Empire. This was done by his father to help assimilate into his society (what better way). His Jewish name was Anchel.
It helps that K is such a harsh and resounding letter. Vowels and M,N,P might not be so effective. We take note of a K.
Joseph K is both an Everyman and Kafka's specific individual. He is anonoymous yet he is a target for the world in which he has no option but to live. He is beset by the law, by the government, by the society which surrounds him. Joseph K is hounded unmercifully until ignominiously stabbed to death by nebulous officials in a pit. It does so seem that both Kafka and K saw the future spreading before them.
Kafka was writing about himself and yet he was not. He could remove himself from his own self yet make his character as much Franz Kafka as if he had been writing an autobiography. Perhaps this is why he never did write a memoir.