Some knowledge of Ubuntu and Linux commands is useful, but the steps below will get you up and running for now.
Commands that you need to type are shown like this:
$ ls ~/dev # Show contents of the
dev/ folder beneath our home folder.
$ sign is to indicate that this is a Linux command, you don't need to type the
$. Likewise don't type any text that starts with
# (these are just comments.)
Install virtual machine
If you have already created a virtual machine, skip the following steps and proceed to Start the VM
- Install VirtualBox
- Obtain the VirtualBox AdoptOpenJDK VM image. Handed out at HackDay, or download before if you have 3+ hours or fast internet, from: http://myco.ws/downloads/Ubuntu_12.04_OpenJDK_dev_1506.ova
- Double click the VM's .ova file (e.g. Ubuntu_12.04_OpenJDK_dev_1506.ova) to open it in VirtualBox, and click the "Import" button.
- (Optional) Change the VM's settings to give more resources. Changing from the defaults to 4 cores and 6GB RAM can reduce JDK build time by around 20%
Start the VM
When the VM has started, login as OpenJDK (password is j1a2v3a4)
Start Firefox to check your internet connection. Google for "adopt OpenJDK getting started" and choose https://www.gitbook.com/book/adoptopenjdk/adoptopenjdk-getting-started-kit/details You can copy & paste commands from these if you like.
Open a Terminal session - Click Ubuntu's top-left start button and type:
pwdto show the current directory. It should be
/home/openjdk- if not then
cd /home/openjdkto that location.
Check and build source files
Check that you have an initial version of the JDK8 source files by typing:
$ ls ~/dev
This should show a directory called `jdk8 , if not do these steps:
hg clone http://hg.openjdk.java.net/jdk8/jdk8 jdk8# Fetch initial Build OpenJDK in that directory as follows:
chmod 755 configure && chmod 755 get_source.sh
bash get_source.sh# Fetch latest sources (including various sub-directories)
bash configure# Initialise the build process with correct settings for your system / VM
make clean images# Build the JDK. This can take a while, tea time?!
This should create the familiar
bin/ directory containing
javac etc under the
build directory, with a name corresponding to your (virtual) machine, something like:
Test this by running:
$ build/linux-x86_64-normal-server-release/images/j2sdk-image/bin/javac -version
You might need to change the
linux-x86_64-normal-server-release part to match your environment.
For subsequent builds, if you didn't make significant changes, try omitting
clean and just type:
$ make images # Faster than clean (and might suffice.)
Running your newly built JDK
Now use your shiny new JDK to build and run a simple program such as printing:
Either do this directly using the full path to the bin/ directory as above, or by pointing the environment to your new JDK using the following steps (as before, you might need to change the
linux-x86_64-normal-server-release part to match your environment) :
$ export JAVA_HOME=/home/openjdk/dev/jdk8/build/linux-x86_64-normal-server-release/images/j2sdk-image
$ export PATH=$JAVA_HOME/bin:$PATH
Similarly you can revert it back to another JDK by inspecting
See the main OpenJDK Getting Started section, and try some of these ideas:
- Change the Random.java class.
- Change the StringBuffer.java class to add a new method.
- Test latest Java by building your open source project on it.
- Build a different JDK such as jdk9 or jdk8u NOTE for jdk9 see Adenda below
- Check out options for the
- Investigate some new JDK9 features such as:
- The Java Shell (Read-Eval-Print Loop) jshell
- New Version-String Scheme
- Try the new Jan'16 build infrastrucure for around 40% improvement in build times, refer to description and Mailing list.
- Choose a Java Enhancement Proposal (JEP) to implement.
- Look at existing issues in JDK Bug Database. Click a project (such as JDK) then click an icon on the left (eg Backlog).
- and other ideas in the beginners and intermediate and advanced sections.
25 Jan 2017. Newer gcc needed.
If jdk9 build fails with a
/usr/bib/ld error you might need a later version of gcc than the 4.6 provided by the
_1506_ VM. To update to gcc 4.9 do the following: sudo add-apt-repository ppa:ubuntu-toolchain-r/test sudo apt-get update sudo apt-get install gcc-4.9 g++-4.9 sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9