If you have chosen to install the full OpenJDK development kit, check the version of the compiler as well: javac -version OpenJDK 64-Bit Server VM 18.9 (build 11.0.7+10-LTS, mixed mode, sharing) OpenJDK Runtime Environment 18.9 (build 11.0.7+10-LTS) This is generally slower than running applications that have already been compiled into Java bytecode, and may not be suitable if you plan to execute applications many times.Ĭheck the version of the JRE to verify that it has been properly installed: java -versionĪs of the time of this publication, this command should return: While you can run Java applications directly with the JRE, your applications will be compiled every time they are executed. Install the OpenJDK 11 development kit, which includes OpenJRE 11: sudo apt-get install openjdk-11-jdkĪlternatively, if you simply want to run Java applications that you have already downloaded, you can choose to only install OpenJRE 11: sudo apt-get install openjdk-11-jre This guide will use sudo commands wherever possible, which should be run by a limited, non-root user on your Linode.Įnsure your system is up-to-date: sudo apt-get update & sudo apt-get upgrade Before You Beginįamiliarize yourself with our Getting Started guide and complete the steps for connecting to your Linode with SSH and setting your Linode’s hostname and timezone.Ĭomplete the sections of our guide on Securing Your Server to create a standard user account, harden SSH access and remove unnecessary network services. For this reason, OpenJDK 11 is the recommended version for developing production applications. While there are many available versions of OpenJDK, version 11 is the latest Long-Term-Support (LTS) release as of the time of this guide’s publication. OpenJDK and Java SE are equivalent JDKs that include a Java runtime environment (JRE) and tools for developing and compiling Java applications. OpenJDK is the free and open-source implementation of the Oracle Java Standard Edition (Java SE) Development Kit. This guide will show you how to install the Open Java Development Kit (OpenJDK) 11 on Ubuntu 18.04. Software written in Java can be compiled and run on any system, making Java a versatile platform that can be used to create anything from software to basic web applications. Java is one of the world’s most popular programming languages. There are 2 choices for the alternative java (providing /usr/bin/java).Updated Wednesday, by Linode Contributed by Rajakavitha Kodhandapani % sudo apt-get install -only-upgrade default-jdk Once OpenJDK 11 appears in Ubuntu 18.04, it’s going to be just a matter of a package upgrade and an alternatives switch to use it. % sudo sh -c 'for bin in /usr/lib/jvm/jdk-11/bin/* do update-alternatives -set $(basename $bin) $bin done' % sudo sh -c 'for bin in /usr/lib/jvm/jdk-11/bin/* do update-alternatives -install /usr/bin/$(basename $bin) $(basename $bin) $bin 100 done' For that reason, I’m using the alternatives framework with which it’s possible to switch between JDKs easily. In this case, that isn’t an option, not yet at least. I would prefer to use the distro’s JDK as long as it works for the task at hand. OpenJDK 64-Bit Server VM 18.9 (build 11+28, mixed mode) Switching between JDKs OpenJDK Runtime Environment 18.9 (build 11+28) % sudo tar xfvz /tmp/openjdk-11+28_linux-圆4_ -directory /usr/lib/jvm That’s easy too, you just have to download a tarball and extract it somewhere. OpenJDK 64-Bit Server VM (build 10.0.2+13-Ubuntu-1ubuntu0.18.04.2, mixed mode) Installing OpenJDK manually Nevertheless, do check what Java version does that actually install. This is very simple, you just need the following package. In fact, the JVM fails to start and complains about unrecognized options. OpenJDK 10 doesn’t contain flight recorder, as at that time it was a commercial feature of Oracle JDK, but OpenJDK 11 does come with it.Īs a consequence, installing openjdk-11-jdk doesn’t allow applications to be instrumented with JFR, as the JVM options used to enable it simply aren’t getting recognized by OpenJDK 10. There’s one area tiny though where there’s a significant difference between 10 and 11 and that’s that Flight Recorder got open sourced in the meantime.
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