JDK Installation

1. Download jdk for linux from oracle official site or from here.
   • Download tar.gz file for jdk
   • eg : jdk-13.0.2_linux-x64_bin.tar.gz file 
2. Create folder inside /opt for java-jdk installation

   sudo mkdir /opt/java-jdk 

3. Since JDK downloaded is compresses so uncompress(untar) JDK file to /opt/java-jdk    

   sudo tar -C /opt/java-jdk -zxf /home/lenovo/Downloads/jdk-13.0.2_linux-x64_bin.tar.gz

4. Install java in  usr/bin/java with priority 1 

   sudo update-alternatives  --install /usr/bin/java java /opt/java-jdk/jdk-13.0.2/bin/java 1

5. Install javac in usr/bin/javac with priority 1

   sudo update-alternatives  --install /usr/bin/javac javac /opt/java-jdk/jdk-13.0.2/bin/javac 1

Setup path for JDK

1. Open terminal –>ctrl+alt+t 

   lenovo@jags:~$ sudo gedit  /etc/profile

   • opens “profile” file to add java_home directory 
2. Add following codes to “profile” file

JAVA_HOME=/opt/java-jdk/jdk-13.0.2
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
export JAVA_HOME 
export JRE_HOME
export PATH