How to Set Environment Variables for Java

Introduction

Java is an object-oriented programming language that is based on classes and can be employed mostly to develop web and desktop applications. No matter the computer architecture, Java applications are often compiled to byte code that can operate on every JVM (Java virtual machine).

What exactly is an Environmental Variable?

The environment variable is just a value with something like a dynamic name that can determine how running processes behave on a computer. They are a feature of the setting in which a process operates.

Using Environment Variables in Java

Environment variables are created to keep command line tools accessible and to make it simpler for other tools to communicate with SDKs. Environment variables are a fantastic way to configure Java applications without explicitly storing settings in code, such as for database and caching servers or third-party application programming interfaces. By using the environment variables for configuration, there might be many advantages to the users for easy access and for creating programmes much more flexible.

A few of the Advantages of using Environmental Variables are:

· The similar code is further implemented in various environments. 

· When settings change, there is no requirement to update and recompile the code. 

· It supports stopping the visibility of sensitive credentials such as usernames and passwords while also protecting deployment tokens.

Setting up Environment Variables on Systems

Environment variables can be set in three of the core operating systems. The operating systems have different ways of creating and installing process steps.

• Windows 

• macOS 

• Linux 

Before setting up environment variables, we need to know about some Java concepts like how to install JDK (java development kit) and the execution of Java programmes using JVM and JRE.

JDK (Java Development Kit)

The Java Development Kit (JDK) can be defined as a software program developing environment for creating Java programs and applets. The JDK provides the tools required for building Java programs. It includes a compiling engine, Java launcher, applet viewer, and much more. The compiler translates Java code into respective bytecodes. The Java Application Launcher loads required classes runs the main function, and starts the Java Runtime Environment (JRE).

JRE (Java Runtime Environment)

For something like the purpose of executing applets and applications created in the Java programming language, it frequently uses runtime libraries, util, lang, AWT, and package classes such as math, swing, and others. This Java Runtime Environment (JRE) includes a set of libraries, JVM, as well as other components. The JRE also provides Java Web Start, which delivers standalone applications over a network, and Java Connector, which enables applets to run in very well browsers.

JVM (Java Virtual Machine)

Many programming languages have compilers that generate machine code for platforms. A Java compiler, on the other hand, produces Java Virtual Machine code. A Java Virtual Machine (JVM) is the standard running time environment where Java code or applications are executed. Java bytecode is converted to machine code. The Java Runtime Environment (JRE) seems to contain the Java Virtual Machine (JVM). 

Downloading and Installation of Java

If we want to run programmes based on Java, we can download platforms like NetBeans, Eclipse, Solar Eclipse, and others. But to run all the above-mentioned applications, we need to download JDK (Java Development Kit) to get full access to Java applications. The steps that need to be followed to download the JDK are as follows.

1. Firstly, go to the official Oracle page (Java Downloads | Oracle). Oracle is now the publisher of Java. Previously, Java was used to release official Sun Microsystems.
2. After reaching downloads, it displays the recent versions of Java. Click on the recent version of Java to download.
3. Go to the JDK download page, accept the license agreement, and then download the JDK for Windows, depending on whether our operating system is 32-bit or 64-bit.
4. Proceed to the next step to install the latest version of JDK on our system. Go to the folder where we saved the JDK. Double-click the .exe file to start the installation process.
5. Now, a screen will appear where we click next. Then a custom setup screen appears where we click the next button again. Then a few files are downloaded for some time.
6. Now, it asks for the location for JRE. Keep the default location and click Next. Now the actual installation begins, and a screen appears once the installation is completed. Now click the close button.
7. To ensure that the installation is successful, navigate to the Java folder in Program Files. We'll notice that new JRE and JDK folders with the most recent version numbers have been formed. Don't be concerned if we find earlier versions of JRE or JDK folders. Multiple JDK and JRE versions can exist simultaneously.

After the completion of downloading and installing Java on our system, the next step is to set environment variables on our system. The procedure for setting variables is different across all the platforms. Now let's see the steps to set environment variables in different operating systems.

Windows

• System variables and user variables are indeed the two sets of environmental variables employed by the Windows operating system. Once Java has been installed on our computer, we must configure the environment variable. Launch the JDK folder now.
• Open the JDK folder that corresponds to the most recent version if we have many JDK folders, and then copy the respective JDK folder's location.
• We must now launch our computer's environment variables window. Now follow the instructions. Click the Start menu to get started. 
• Next, perform a right-click on the computer and choose the Properties button to go to the next step. In the next pop-up window, look out for the control panel window. Under the control panel window, there are four options mentioned: device manager, remote settings, system protection, and advanced system settings. Now click on advanced system settings.
• Upon clicking the advanced system settings button, this will navigate to the system properties window. There, under the advanced tab, look for the environment variables button on the top-down right side of the window. Click the respective environment variable button. 
• The "Path" variable under System variables must now be changed to include the path to the software environment. Click the Edit button after choosing the "Path" variable. Now we will see several paths. Click the new button to set up a path. Now paste the previously copied path of the jdk folder and add the path for the environment variable.
• The final stage is completing the setup by clicking OK now, and the environment variable is successfully added to our system variables. 
• To check if the installation is completed or not, type the javac –version on the command prompt. Therefore, we can see that Java is successfully running on our computer.

macOS

• By pressing the "cmd" and "shift" keys simultaneously, we can open the terminal by selecting it from the application folder or by typing the terminal's initials and pressing Enter. 
• Write the command "java-version" first in order to configure, and a message stating that there is no such command will appear below it.

Java --version

javac –version

• After completion of JDK download and installation, we can now move further to set up the Java _ home environment variable. But to do this, look for something like bash _ profile Type the following command to check for a bash profile:

ls - al  

• To check whether it is installed or not, use the following command by typing in the terminal to setup

echo $JAVA_HOME

• After this, we are done setting up environment variables in the macOS operating system.

Linux

There are various methods for installing Java on Linux. But we'll discuss the quickest and most straightforward method of installing Java via a terminal. We will set up OpenJDK on Linux. The Java programming language is implemented by OpenJDK, which is open-source and free. To set up the environment variables in Linux operating system, given below are the processing steps.

• Open the system and navigate to Applications, then go to Accessories, followed by Terminal. On the terminal, type the command.

 sudo apt-get install openjdk-( version number)-jdk

• Now for the environment variable mentioned Java _ home above, in the terminal, type the command of the default or, alternatively, set the path of the OpenJDK folder location. An example is shown below.

export JAVA_HOME = (path of the java version open jdk folder copied)

• Now to set the path environment variable, again in the same terminal, type the command

export PATH = $PATH: ( installation path of OpenJDK folder)

• After exporting both java _ home and path variables, we are successfully done completing the installation and setting up of variables.

Conclusion

With a very minimal memory footprint, environment variables provide a helpful way to alter how Windows behaves. Fortunately, setting environmental variables is fairly straightforward and extremely valuable. For instance, PATH is a typical environment variable that simply lists the folders that Windows should search for when an executable programme is called. Thanks to the PATH environment variable, users can rapidly launch programmes without knowing where they are located on the hard drive.