Ubuntu: change the path from OpenJDK 6 to Oracle JDK 7

Question

After downloading the latest .tar file I ran tar zxvf jdk-7u45-linux-x64.tar.gz to extract java files.

Set the path in .bashrc file (vi ~/.bashrc) as below;

export JAVA_HOME=/usr/lib/jvm/jdk1.7.0_45/bin/java
export PATH=$PATH:/usr/lib/jvm/jdk1.7.0_45/bin
export JDK_HOME=/usr/lib/jvm/jdk1.7.0_45    
export JRE_HOME=/usr/lib/jvm/jre1.7.0_45

Now, running command java -version or which java, java PATH still pointing to the older java version (java version "1.6.0_27").

I know default ubuntu takes OpenJDK path. I have to change the path as latest version as my system environment variable set in .bashrc file.

Also, sudo update-alternatives --config java

Selection    Path                                      Priority   Status
------------------------------------------------------------
  0            /usr/lib/jvm/java-7-oracle/jre/bin/java    1062      auto mode
  1            /usr/lib/jvm/java-6-openjdk/jre/bin/java   1061      manual mode
  2            /usr/lib/jvm/java-7-oracle/jre/bin/java    1062      manual mode
* 3            /usr/lib/jvm/jdk1.7.0_45/bin/java          1         manual mode
Press enter to keep the current choice[*], or type selection number: 3

Answer 1

Ubuntu (and Debian) have an elegant way to manage libraries like the jdk.

Using update-alternatives you can manage multiple jdk libraries on the same system, choosing which one you want to use as the main one.

First you have to install an alternative for the new installed jdk:

sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/jdk1.7.0_45/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/jdk1.7.0_45/bin/javac" 1

In this way you install the new jdk as an alternative to the original one. Then you can choose which one you wan to use:

sudo update-alternatives --config java
sudo update-alternatives --config javac

You will be asked to choose which jdk you want to use, on my system I have:

There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                           Priority   Status
------------------------------------------------------------
  0            /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java   1061      auto mode
  1            /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java   1061      manual mode
* 2            /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java   1051      manual mode

Press enter to keep the current choice[*], or type selection number: 

At any time you can see what alternatives you have for java or javac using the --list option:

sudo update-alternatives --list java
sudo update-alternatives --list javac

To see more options check the update-alternatives man page.