Oracle Developer Senior interview questions

Thourough multi step technical interview process, mostly system design, but covering algorithms as well in one of these. Lots of questions about previous experience and motivation for applying for the company.

Initially got call from HR about opportunity. I accepted and they scheduled interview 1st Round(Technical) : The first round was technical and mostly focussed on java, DS and few thread related questions about my work. 2nd Round(Dev manager and Director): The next day I got call from Dev manager about second round and they scheduled it next day. The interview was again decent. Focus was mainly on core java file operations and problem on string. Then a puzzle was asked. I answered most of them. Later the Director joined the call and asked details intro and project experience. And finally they rolled out offer details. Waiting for offer letter now. They said it would take up to 20 days