how can i upgrade only jre from 7 to jre 8 on ubuntu 1404
Solution 1:
OpenJDK 8 for Trusty isn't available in the official Ubuntu repositories.
As a workaround, you can install OpenJDK 8 from a PPA.
Open a terminal and execute:
sudo apt-add-repository ppa:openjdk-r/ppa
sudo apt-get update
sudo apt-get install openjdk-8-jdk
Or if you only need the JRE
sudo apt-get install openjdk-8-jre
It is usual that several major versions are installed in parallel.
To switch between Java 7 and Java 8 use this command:
sudo update-alternatives --config java