When I installed the Android Developer Studio and started it, I got the message that OpenJDK has performance issues and that one should install the JDK/JRE by Oracle. Oracle offers only tar-balls and rpms, thus I needed to find a way to install it. Thanks to Google the solution wasn’t far away but for making it easier findable for me, I post the way I did it in the end here as well in a more generalized way.
Download the JDK from Oracle, then start by removing OpenJDK:
sudo apt-get update && apt-get remove "openjdk"
Then go to your downloads-directory and untar the tar.gz (tar -xzvf jdk-$version)
Create a folder in /opt for the jdk:
sudo mkdir -p /opt/java
Move the JDK to the folder:
sudo mv ~/Downloads/jdk$version /opt/java/
Make the JRE and JDK the default
sudo update-alternatives --install "/usr/bin/java" "java" "/opt/java/jdk$version/bin/java" 1
sudo update-alternatives --set java /opt/java/jdk§version/bin/java
sudo update-alternatives --install "/usr/bin/javac" "javac" "/opt/java/jdk$version/bin/javac" 1
sudo update-alternatives --set javac /opt/java/jdk§version/bin/javac