How to set Oracle s Java as the default Java in Ubuntu

Question

How do I change the value of JAVA HOME in Ubuntu to point to Oracle s Java    Should it point to java-6-sun or java-6-sun-1 6 0 24

User · Answer

java 6  export JAVA HOME  usr lib jvm java-1 6 0-openjdk-amd64  or java 7  export JAVA HOME  usr lib jvm java-1 7 0-openjdk-amd64

User · Answer

See this  run   sudo  update-java-alternatives --list   to list off all the Java installations on a machine by name and directory  and then run  sudo  update-java-alternatives --set  JDK JRE name e g  java-8-oracle    to choose which JRE JDK to use     If you want to use different JDKs JREs for each Java task  you can run update-alternatives to configure one java executable at a time  you can run   sudo  update-alternatives --config java Tab    to see the Java commands that can be configured  java  javac  javah  javaws  etc    And then   sudo  update-alternatives --config  javac java javadoc etc     will associate that Java task command to a particular JDK JRE   You may also need to set JAVA HOME for some applications  from this answer you can use  export JAVA HOME   readlink -f  usr bin java   sed  s bin java       for JREs  or   export JAVA HOME   readlink -f  usr bin java   sed  s jre bin java       for JDKs

User · Answer

If you re doing any sort of development you need to point to the JDK  Java Development Kit   Otherwise  you can point to the JRE  Java Runtime Environment    The JDK contains everything the JRE has and more  If you re just executing Java programs  you can point to either the JRE or the JDK   You should set JAVA HOME  based on current Java you are using   readlink will print value of a symbolic link for current Java and sed will adjust it to JRE directory   export JAVA HOME   readlink -f  usr bin java   sed  s bin java       If you want to set up JAVA HOME to JDK you should go up one folder more   export JAVA HOME   readlink -f  usr bin java   sed  s jre bin java

User · Answer

I put the line   export JAVA HOME  usr lib jvm java-7-oracle   in my    bashrc file    usr lib jvm java7-oracle should be a symbolic link pointing to  usr lib jvm java-7-oracle- version number here    The reason it s a symbolic link is that in case there s a new version of the JVM  you don t need to update your  bashrc file  it should automatically point to the new version   If you want to set JAVA HOME environment variables globally and at system level means use should set in  etc environment file

User · Answer

If you want to use specific version of Java when multiple JDKs are installed  just setting JAVA HOME may not work    You need to use sudo update-alternatives --config java to set default Java    Refer to https   askubuntu com questions 121654 how-to-set-default-java-version

User · Answer

If you want this environment variable available to all users and on system start then you can add the following to  etc profile d java sh  create it if necessary    export JDK HOME  usr lib jvm java-7-oracle export JAVA HOME  usr lib jvm java-7-oracle   Then in a terminal run   sudo chmod  x  etc profile d java sh source  etc profile d java sh        My second question is - should it point to java-6-sun or java-6-sun-1 6 0 24     It should always point to java-7-oracle as that symlinks to the latest installed one  assuming you installed Java from the Ubuntu repositories and now from the download available at oracle com

User · Answer

If you want to change it globally and at system level   In   etc environment   add this line   JAVA HOME  usr lib jvm java-7-oracle

User · Answer

to set Oracle s Java SE Development Kit as the system default Java just download the latest Java SE Development Kit from here then create a directory somewhere you like in your file system for example  usr java now extract the files you just downloaded in that directory     sudo tar xvzf jdk-8u5-linux-i586 tar gz -C  usr java   now to set your JAVA HOME environment variable     JAVA HOME  usr java jdk1 8 0 05    sudo update-alternatives --install  usr bin java java   JAVA HOME     bin java 20000   sudo update-alternatives --install  usr bin javac javac   JAVA HOME     bin javac 20000   make sure the Oracle s java is set as default java by     update-alternatives --config java   you get something like this   There are 2 choices for the alternative java  providing  usr bin java      Selection    Path                                           Priority   Status ------------------------------------------------------------   0             opt java jdk1 8 0 05 bin java                  20000     auto mode   1             opt java jdk1 8 0 05 bin java                  20000     manual mode   2             usr lib jvm java-6-openjdk-i386 jre bin java   1061      manual mode  Press enter to keep the current choice     or type selection number    pay attention to the asterisk before the numbers on the left and if the correct one is not set choose the correct one by typing the number of it and pressing enter  now test your java     java -version   if you get something like the following  you are good to go   java version  1 8 0 05  Java TM  SE Runtime Environment  build 1 8 0 05-b13  Java HotSpot TM  Server VM  build 25 5-b02  mixed mode    also note that you might need root permission or be in sudoers group to be able to do this  I ve tested this solution on both ubuntu 12 04 and Debian wheezy and it works in both of them

[java] How to set Oracle's Java as the default Java in Ubuntu?

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