Enter the following commands in the terminal of ubuntu to configure JDK and hosts
configure hosts
sudo gedit /etc/hosts Open hosts file
sudo /etc/init.d/networking restart restart the network connection
Configure JDK
sudo tar zxvf jdk-8u101-linux-x64.tar.gz -C /usr/lib/jvm Extract the JDK package to /usr/lib/jvm
cd /usr/lib/jvm into this folder
sudo mv jdk1.8.0_101 java move files to this folder
sudo gedit ~/.bashrc open bashrc file
sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/java/bin/java 300
sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/java/bin/javac 300
sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/java/bin/jar 300
sudo update-alternatives --install /usr/bin/javah javah /usr/lib/jvm/java/bin/javah 300
sudo update-alternatives --install /usr/bin/javap javap /usr/lib/jvm/java/bin/javap 300
sudo update-alternatives --config java
java -version