I wanted to install OpenJDK-8 on Ubuntu 14.04. So as described here I tried to find the correct name of package (which is openjdk-8-jdk) and run these commands:
sudo apt-get update
sudo apt-get install openjdk-8-jdk
But I got:
E: Unable to locate package openjdk-8-jdk
So I went to Ubuntu Packages Search and Ubuntu Updates and searched for package. But I could not find any thing about trusty (14.04LTS) or trusty-updates. So I was sure there is no install able package to be installed on Ubuntu 14.04.
Of course after sometimes I suddenly found that package belongs to openjdk-r/ppa repository and added that:
sudo add-apt-repository ppa:openjdk-r/ppa
But I want to know how I can find appropriate repository (in above example the openjdk-r/ppa) before consuming times and waiting for chance?