Installing java 8

Ok so sdkman can do this, and it installs to

/home/vagrant/.sdkman/candidates/java/current/bin/java

Even man pages work. But why? MANPATH is not set...

Edit: solved that mystery.

path directory /home/vagrant/.sdkman/candidates/java/current/bin is not in the config file
  adding /home/vagrant/.sdkman/candidates/java/current/man to manpath

Also what are the steps to install java normally in debian? Somehow jvm ends up in

/usr/lib/jvm

and the binaries are linked into /usr/bin or somewhere on the PATH