3 reasons to learn Java in 2021: 
Java was released in 1995, making it 26 years old as I’m writing this. It was proprietary at first, but in 2007, Java was released as open source under the GPL. To understand what makes Java important, you have to understand the problem it claims to solve. Then you can understand why and how it benefits developers and users.
read more: Opensource.com sethkenlon
Supporting Open Source.
Have you tried: Diving with Sharks?