how to install Java SE Development Kit 8 ubuntu 15.10

ubuntu 14.04 Java SE Development Kit 8
Java SE Development Kit 8u102


This command will completely remove OpenJDK/JRE from your system
sudo apt-get purge openjdk-\* 

This command will create a directory to hold your Oracle Java JDK and JRE binaries.
sudo mkdir -p /usr/local/java 


Download the Oracle Java JDK/JRE for Linux. Make sure you select the correct compressed binaries for your system architecture 32-bit or 64-bit (which end in tar.gz). 
Select
Linux x64    172.95 MB      jdk-8u102-linux-x64.tar.gz


Copy the Oracle Java binaries into the /usr/local/java directory.
sudo cp -r jdk-8u102-linux-x64.tar.gz /usr/local/java

Unpack the compressed Java binaries, in the directory /usr/local/java 
sudo tar xvzf jdk-8u102-linux-x64.tar.gz


Edit the system PATH file /etc/profile and add the following system variables to your system path


Scroll down to the end of the file using your arrow keys and add the following lines below to the end of your /etc/profile file:

JAVA_HOME=/usr/local/java/jdk1.8.0_102
JRE_HOME=$JAVA_HOME/jre
PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
export JAVA_HOME
export JRE_HOME
export PATH


Inform your Ubuntu Linux system where your Oracle Java JDK/JRE is located. 
If you are installing the JDK then Type/Copy/Paste: 
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jdk1.8.0_102/jre/bin/java" 1

Only if you are installing the JDK then Type/Copy/Paste: 
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk1.8.0_102/bin/javac" 1 



Inform your Ubuntu Linux system that Oracle Java JDK/JRE must be the default Java.
If you are installing the JDK then Type/Copy/Paste: 
sudo update-alternatives --set java /usr/local/java/jdk1.8.0_102/jre/bin/java
If you are installing the JDK then Type/Copy/Paste: 
sudo update-alternatives --set javaws /usr/local/java/jdk1.8.0_102/bin/javaws

test jdk installation
http://www.javatester.org

java -version
java version "1.8.0_102"
Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)


64-bit Oracle Java instructions
To enable your Java plug-in in your web browsers you must make a symbolic link from the web browsers plug-in directory to the location of the Java plug-in included in your distribution of Oracle Java.

cd /usr/lib/firefox-addons/plugins/
sudo ln -s /usr/local/java/jdk1.8.0_102/jre/lib/amd64/libnpjp2.so

oracle java control panel to add website in exception list
/usr/local/java/jdk1.8.0_102/bin/ControlPanel