Install Java USing APT

Launch a terminal.
Execute one of the following lines:
  sudo apt-get install oracle-java8-installer #for jdk 8
  sudo apt-get install oracle-java7-installer #for jdk 7
It runs wget and downloads the tar file	wget --continue --no-check-certificate -O jdk-8u74-linux-i586.tar.gz --header Cookie: oraclelicense=a http://download.oracle.com/otn-pub/java/jdk/8u74-b02/jdk-8u74-linux-i586.tar.gz
From
http://download.oracle.com/otn-pub/java/jdk/8u74-b02/jdk-8u74-linux-i586.tar.gz	http://download.oracle.com/otn-pub/java/jdk/8u74-b02/jdk-8u74-linux-i586.tar.gz?AuthParam=1456945187_330799f5b37746da233ebb0427ffb4c1
Then correctly installs and sets this JDK as system default JDK.