You might be right :) I was not looking for a better implementation. I was looking for the simplest and one of the well-known bitcoin libraries. bitcoinj worked well for me. It is simple to use.

But again, thank you, guys, for offering other good ones. It is appreciated.

I wrote two articles about Bitcoin and Ethereum on medium and hackernoon. Please take a look :)

https://hackernoon.com/how-to-generate-bitcoin-addresses-tec...

https://hackernoon.com/how-to-generate-ethereum-addresses-te...