Write once, run many
The Java™ Tutorials by Oracle
The Java Tutorials are practical guides for programmers who want to use the Java programming language to create applications. They include hundreds of complete, working examples, and dozens of lessons. Groups of related lessons are organized into "trails".
https://docs.oracle.com/javase/tutorial/Learn to Program in Java at edX.ogr
Get started on the path to becoming a software engineer by learning core coding skills in Java—one of the most popular programming languages.
https://www.edx.org/course/learn-to-program-in-java-0Java Tutorial by javapoint.com
https://www.javatpoint.com/java-tutorialJava Tutorial by SoloLearn.com
I love SoloLearn because I can learn Java - and other popular programming languages - anywhere, any time on your mobile devices.
https://www.sololearn.com/Course/Java/Java on Azure
https://docs.microsoft.com/en-us/learn/paths/java-on-azure/
