THIS is the best source to learn java for beginners as well as everyone who want to master java language. Durga sir is a java pioneer and has very good command on the language. He teaches so good that onece you have started learning from him you will get addicted to it. Unlike many other online courses he teaches everything in very detail with very good examples and you will never forget the concept once you have learned from Durga sir.
After finishing the series I linked above you can watch this series also. Beginners should watch the series in the order given below. People who have basic idea can watch the series acc. to there relevance.
- Operators and assignment
- Declaration and access modifier
- Lang package
- Collections framework(very important for competitive programming.)
- OOPs concepts
- Multi Threading
you can site there you tube channel for other series also.