install oracle jdk on ubuntu

solution

1. reference

   1. wikihow

2. steps

   1. check java version

       $ java -version
      

   2. remove openjdk/jre

       $ sudo apt-get purge openjdk-\*
      

   3. copy jdk-7u79-linux-x64.tar.gz to /usr/local/java

       $ sudo cp -r jdk-7u79-linux-x64.tar.gz /usr/local/java
      

   4. unpack

       $ sudo tar zxf jdk-7u79-linux-x64.tar.gz
      

   5. double-check

       $ ls -a
       jdk1.7.0_79
      

   6. edit /etc/profile

       # at the end of file
       $ pico /etc/profile
       JAVA_HOME=/usr/local/java/jdk1.7.0_79
       JRE_HOME=$JAVA_HOME/jre
       PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
       export JAVA_HOME
       export JRE_HOME
       export PATH
      

   7. inform os where oracle jdk/jre located

       $ sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jdk1.7.0_79/bin/java" 1
       $ sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk1.7.0_79/bin/javac" 1
       $ sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/local/java/jdk1.7.0_79/bin/javaws" 1
      

   8. inform os that oracle jdk/jre is default java

       $ sudo update-alternatives --set java /usr/local/java/jdk1.7.0_79/bin/java
       $ sudo update-alternatives --set javac /usr/local/java/jdk1.7.0_79/bin/javac
       $ sudo update-alternatives --set javaws /usr/local/java/jdk1.7.0_79/bin/javaws
      

   9. reload system wide PATH

       $ . /etc/profile
       $ java -version
      

   10. reboot

        $ sudo reboot