java.lang & java.util & more - Class Hierarchy TREE (Java SE 10 & JDK 10 )

java.lang:

https://docs.oracle.com/javase/10/docs/api/java/lang/package-tree.html

java.util:

https://docs.oracle.com/javase/10/docs/api/java/util/package-tree.html

General main/base packages:

https://docs.oracle.com/javase/10/docs/api/java.base-summary.html

https://docs.oracle.com/javase/10/docs/api/overview-tree.html

Concurrent "root":

https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/package-summary.html

Functions and functional interfaces:

https://docs.oracle.com/javase/10/docs/api/java/util/function/package-tree.html

Streams:

https://docs.oracle.com/javase/10/docs/api/java/util/stream/package-summary.html

https://docs.oracle.com/javase/10/docs/api/java/util/stream/package-tree.html