How to install Oracle Java 8 on Ubuntu

1. Open terminal
2. Type
   sudo apt-get update
   
   sudo apt-get install default-jre sudo apt-get install default-jdk
   
   sudo add-apt-repository ppa:webupd8team/java
   sudo apt-get update
   
   sudo apt-get install oracle-java8-installer
   
   sudo update-alternatives --config java
   
   
3. Choose the java installation number that you want to use as a default
4. Copy the path
5. Type
   sudo gedit /etc/environment
   
   
6. At the end of the file, add the following line:
   JAVA_HOME={DEFAULT JAVA PATH}
   {DEFAULT JAVA PATH} is the java installation number that you selected on step 3
   
   
7. Save the file
8. Close the editor
9. Type
   source /etc/environment

Example:

I want to use the Oracle Java 8 as default and set the JAVA_HOME to it:

1. Open terminal
2. Type
   sudo apt-get update
   
   sudo apt-get install default-jre sudo apt-get install default-jdk
   
   sudo add-apt-repository ppa:webupd8team/java
   sudo apt-get update
   
   sudo apt-get install oracle-java8-installer
   
   sudo update-alternatives --config java
   
   
3. Ubuntu will return to a content similar like the below:
   There are 2 choices for the alternative java (providing /usr/bin/java).
   
     Selection    Path                                            Priority   Status
   ------------------------------------------------------------
   * 0            /usr/lib/jvm/java-8-oracle/jre/bin/java          1082      auto mode
     1            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1081      manual mode
     2            /usr/lib/jvm/java-8-oracle/jre/bin/java          1082      manual mode
   
   Press <enter> to keep the current choice[*], or type selection number: 
   
   
4. Type 0
5. Copy the path of the selection 0 until java-8-oracle ( /usr/lib/jvm/java-8-oracle)
6. Type
   sudo gedit /etc/environment
   
   
7. At the end of the file, add the following line:
   JAVA_HOME=" /usr/lib/jvm/java-8-oracle"
   
   
8. Save the file
9. Close the editor
10. Type
    source /etc/environment

Source: https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-get-on-ubuntu-16-04