How To Set Java Home Path In Linux?


Java is a popular programming language and framework in the IT industry. There are a lot of applications developed with Java. Java requires Java Development Kit to develop applications. Compiled java applications can run on systems those are installed Java Runtime Environment a.k.a JRE. We will look in this post on how to set and check JRE or JDK or Java Home Path.

Installation

There are two main different versions of JDK and JRE. The original vendor is Oracle which distributes and sets standards of Java. Second is an open version of JDK and JRE that are supported by Oracle. In this post, we will install the open version named as openjdk-9-jre-headless.

$ sudo apt-get install openjdk-9-jre-headless -y
Installation
Installation

Check Java Status

We will look if java path already sets simple running java command which is a compiler for Java applications.

$ java
Check Java Status
Check Java Status

Update Locate Database

This is auxiliary operation to use locate OpenJDK location we update locate database

$ sudo updatedb

Find JDK Location

We will look at where is JDK located and also get the JDK version. This operation can be used Oracle JDK too. Just the JDK directory name will be different.

$ locate openjdk
Find JDK Location
Find JDK Location

Set Java Home

As we see there is a lot of output for JDK search we can see that the path of JDK is /usr/lib/jvm/java-9-openjdk-amd64  because it is located in usr lib. Now we will set PATH for Java

$ export JAVA_HOME="/usr/lib/jvm/java-9-openjdk-amd64"
Set Java Home
Set Java Home

Make Java Home Configuration Persistent

The previous step makes JAVA HOME available for subshells but if the system is restarted the path will be lost. So we need to make this path definition persistent. There are different methods to make persistent. We will look single and simple one. We will add path definition to the system-wide environment definition configuration. This operation requires root privileges.

$ echo "JAVA_HOME='/usr/lib/jvm/java-9-openjdk-amd64'" >> /etc/environment
Make Java Home Persistent
Make Java Home Persistent

An alternative method without the need for root privileges is adding Java home path definition to the normal user .bashrc file like below.

$ echo "JAVA_HOME='/usr/lib/jvm/java-9-openjdk-amd64'" >> .bashrc
Make Java Home Configuration Persistent
Make Java Home Configuration Persistent

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