If you're using Ubuntu Linux on your daily basis work, you've probably Java installed on your machine. Personally I prefer using Wepupd8 PPA to manage JAVA installation, it makes my life a lot more easier especially for updates. The Wepupd8 team didn’t add any binary for Oracle JAVA installation and they made a script to download the Oracle JAVA from Oracle website and install it straight away. So whenever Oracle will release the update, I can simple upgrade via package manager.
Working with multiple Java versions in your machine is a normal thing, especially if you're a Java developer, and because I'm a (very) lazy person, I'm always looking for a quicker/easier way to make the switch.
Today, I'll share with you my tip on this subject. First, let's run the following command:
$ sudo update-alternatives --config java
Running this command shows a list of installed Java JDKs and JREs allowing one to be selected as the default that is used when java needs to be executed.
There are 5 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1081 auto mode
1 /usr/lib/jvm/java-6-oracle/jre/bin/java 1 manual mode
2 /usr/lib/jvm/java-7-oracle/jre/bin/java 2 manual mode
3 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1081 manual mode
4 /usr/lib/jvm/java-8-oracle/jre/bin/java 3 manual mode
5 /usr/lib/jvm/java-9-oracle/bin/java 4 manual mode
Press to keep the current choice[*], or type selection number: But I'm using it just to get the Installation path of each Java version.
Then, for each version I created a script that contain the following lines (in the example below, I'm showing the one for java 8):
sudo update-java-alternatives -s java-8-oracle export JAVA_HOME=/usr/lib/jvm/java-8-oracle/ export PATH=$PATH:$JAVA_HOME Note that I'm using u8.sh to make he switch to Java 8, and u9.sh for Java 9 and so on. The final step is to add an alias in ~/.bashrc file to source our script as follow:
...
# Alias
alias u7='source /home/aboullaite/Utils/Java/u7.sh'
alias u8='source /home/aboullaite/Utils/Java/u8.sh'
alias u9='source /home/aboullaite/Utils/Java/u9.sh'
and That's all. Now for switching between Java versions, I only run u8, u7 or u9 ;)