Posted By: Anonymous
So I just installed Ubuntu, and this is my first time working in a Linux environment, so bear with my noobishness here.
Anyway, I downloaded the Java 8 JDK directly from Oracle, but I understand there’s also an OpenJDK for Java 8 as well. I have two questions.
What is the difference between the Oracle version and OpenJDK. Pros/Cons?
When I try and get OpenJDK 8, I can’t. I’m pasting the terminal command and the error message I get here, hoping for advice. Again, very new to Linux, been on my first Linux distro ever for less than an hour here at this point.
[email protected]:~/Java$ sudo apt-get install openjdk-8-jdk Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package openjdk-8-jdk
Any help would be appreciated. In the meantime, I’m just gonna use the Oracle package. Thanks.
So, now I have a new problem. I installed OpenJDK 7, it came with Maven and just installed before I realized I was getting a two-for-one deal. Now I have JDK 7, and Eclipse, and Maven, and they’re all working, but I’m stuck on JDK 7 rather than 8.
I saw that there’s a link below, I intend to check it out in the morning, it’s 2am and I’m tired right now. Any other advice for this new issue would be appreciated, otherwise I will definitely be checking out that link first thing in the morning.
UPDATE: installation without root privileges below
I advise you to not install packages manually on ubuntu system if there is already a (semi-official) repository able to solve your problem. Further, use Oracle JDK for development, just to avoid (very sporadic) compatibility issues (i’ve tried many years ago, it’s surely better now).
Add the webupd8 repo to your system:
sudo add-apt-repository ppa:webupd8team/java sudo apt-get update
Install your preferred version of jdk (versions from java-6 to java-9 available):
sudo apt-get install oracle-java8-installer
You can also install multiple version of jdk, mixing openjdk and oracle versions.
Then you can use the command update-java-alternatives to switch between installed version:
# list available jdk update-java-alternatives --list # use jdk7 sudo update-java-alternatives --set java-7-oracle # use jdk8 sudo update-java-alternatives --set java-8-oracle
If you get
add-apt-repository: command not found be sure to have
sudo apt-get install software-properties-common
If you’re using an older version Ubuntu:
sudo apt-get install python-software-properties
JDK installation without root privileges
If you haven’t administrator rights on your target machine your simplest bet is to use
sdkman to install the zulu certified openjdk:
curl -s "https://get.sdkman.io" | bash source "$HOME/.sdkman/bin/sdkman-init.sh" sdk install java
NOTE: sdkman allow to install also the official Oracle JDK, although it’s not a the default option. View available versions with:
sdk ls java
Install the chosen version with:
sdk install java <version>
sdk install java 9.0.1-oracle
Glossary of commands
<command> [command_arguments]: execute a command with the superuser privilege.
<PPA_id>: Ubuntu (just like every Debian derivatives and generally speaking every Linux distribution) has a main repository of packages that handle things like package dependencies and updating. In Ubuntu is possible to extend the main repository using a PPA (Personal Package Archive) that usually contains packages not available in the system (just like oracle jdk) or updated versions of available ones (example: LibreOffice 5 in LTS is available only through this PPA).
[install|update|upgrade|purge|...]: it’s “the” command-line package handler used to manipulate the state of every repository on the system (installing / updating / upgrading can be viewed as an alteration of the repository current state).
In our case: with the command
sudo add-apt-repository ppa:webupd8team/java we inform the system that the next repository update must retrieve packages information also from webupd8 repo.
sudo apt-get update we actually update the system repository (all this operations requires superuser privileges, so we prepend sudo to the commands).
sudo apt-get install oracle-java8-installer
update-java-alternatives (a specific java version of update-alternatives): in Ubuntu several packages provides the same functionality (browse the internet, compile mails, edit a text file or provides java/javac executables…). To allows the system to choose the user favourites tool given a specific task a mechanism using symlinks under
/etc/alternatives/is used. Try to update the jdk as indicated above (switch between java 7 and java 8) and view how change the output of this command:
ls -l /etc/alternatives/java*
In our case:
sudo update-java-alternatives --set java-8-oracle update symlinks under /etc/alternatives to point to java-8-oracle executables.
<command>: start using man to read a really well written and detailed help on (almost) every shell command and its options (every command i mention in this little answer has a man page, try
search <search_key>: query the APT cache to search for a package related with the search_key provided (can be the package name or some word in package description).
show <package>: provides APT information for a specific package (package version, installed or not, description).