So I'm using
This bad decision was made by a developer in the year 2006. Here is a nice citation from someone that explains the whole situation from java perspective:
"As you probably guessed by now it's a bug (http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6382788). Not the retry mechanism, of course, that's just crap. The bug is that it also happens for a POST (which is by default not idempotent per HTTP RFC). But don't worry, Bill fixed that bug a long time ago. Bill fixed it by introducing a toggle. Bill learned about backward compatibility. Bill decided it's better to leave the toggle 'on' by default because that would make it bug-backward-compatible. Bill smiles. He can already see the faces of surprised developers around the globe running into this. Please don't be like Bill?"
Well the proposed solution is:
But we cannot do this on android! The only remaining solution then is:
EDIT: I could not use this implementation so i looked for an alternative library. I found out that the implementation of HttpUrlConnection uses OkHttp since Android 4.4. As OkHttp is opensource i could search if they have also problems with silent retries. And yep they had problems with it and fixed it in April, 2016. CommonsWare (a real android expert) explains that every manufacturer can decide which implementation they can use. As a consequence of this there must be a lot of devices out there that do silent retries on POST requests and as a developer we only can try some workarrounds.
My solution will be to change the library
EDIT 2: To give you a final answer: You can now use OkHttp as the transport layer for Volley with minimal code.