Command run java command prompt

How to run a Java program from the Command Prompt

Java is one of the most commonly used and sought-after programming languages in the world right now. It is used in varied fields such as software engineering, data science, etc. Much like any other language, code for this language is written in an IDE (Integrated Development Environment). Some users may not, however, prefer downloading a third-party software to write code on and thus prefer built-in text editors like Microsoft Word or Notepad. While these may allow you to write code, they can’t help you run it. This is where the Command Prompt may be of help to you. In this article, we will be demonstrating how you can run a Java program using Command Prompt.

While we will be talking exclusively about Command Prompt, this functionality exists for its macOS counterpart, Terminal, too. The process is the same for Mac as it is for Windows. As a prerequisite, you’re required to download a dedicated Java compiler on your computer. You can download the Java Development Kit (JDK), which runs across platforms as the most important toolkit to writing Java code, from the Oracle website. You’ll have to have the JDK downloaded and installed on your computer before you can begin the process.

How to run a Java program using Command Prompt

First things first, you will have to write the code that you want to run and save that as a Java executable file. For this purpose, you can use either MS Word or Notepad. For example, we’ll be writing a simple code that gives the output “Hello World!”. This is what the code would look like:

Users should make sure of proper indentations since neither Notepad nor Word would help you with that, and also that the file is saved as a ‘.java’ file and not as a ‘.txt’ file. In order to do so, name your file as ‘SampleFile.java’ (You can name the file anything, as long as the file extension is .java and from File type, select ‘All Files’. This file is to be saved in a separate folder in whichever destination you prefer.

Now, open the Command Prompt and run it as administrator. We will make use of the ‘cd’ command to change the operating directory on the Command Prompt to the one where your Java program is stored. Run the following command line:

cd Folder-destination[Java-program-folder]

You can check if your Java program file is present in this directory by using the Dir command too. Now, locate the path of the JDK on your computer, and set the path to the JDK via the following command line. For example, if you’re running the 64-bit Windows version (since that’s most commonly the case), and you decide to install the 64-bit JDK file, your folder destination will be “C:\Program Files\Java”, unless you decide to change it during installation.

set path=%path%;C:\Program Files\Javajdk

Next up, use the javac command (Java compile) to compile your program.

You have to follow the javac keyword after the filename that you’ve chosen for your program. You won’t see anything happen just yet, since the program has only been compiled and not run yet. Finally, to run the command, use the Java command.

If you’re compiling simple programs and housing them all in the same directory, you don’t have to set a permanent path for your files, but if the case is otherwise, then you will be better off doing so. The Command Prompt sets the environmental variable for that session, but those settings are forfeited once you close Command Prompt and your session is timed out. Thus, if you want to set a permanent path for all your future sessions, you can follow the steps below:

Open the Control Panel and visit the System and Security settings. You can locate them by viewing Control Panel settings as Category. This page can, alternatively, be approached via the Windows settings too. From the left-side options pane, select Advanced System Settings and click on the Environment Variables button on the bottom of the System Properties box.

Under the System Variables, you will find the Path variable. Select that and click on Edit, which is right below it.

In the Edit Environment Variable box, click on New, which will allow you to add a new directory to your path.

Here, paste the path that you’ve used above while compiling the Javascript and save the settings by clicking on Ok.

These are steps you have to follow in order to compile and run a Java program using the Command Prompt. As a side note, users should keep in mind to use the Java Development Kit for the procedure and not the Java Runtime Environment, which is something probably most Java programmers, who are reading this article, already have installed and running on their computers.

You can download the JDK from Oracle.com. We hope that this article was able to help you.

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How to Run a Java Program from the Command Prompt

Java is one of the most commonly used programming languages. It is also an IDE-intensive programming language, with tight integration with Eclipse. You can run Java programs from the Command Prompt for quick compiling and execution.

If you are just starting to learn Java, this basic guide will help you start running the Java application from the Command Prompt in Windows 10/11.

Content

Installing the Java Development Kit (JDK) in Windows

Before you can run a Java program on your computer, you’ll need to have a dedicated compiler installed. This comes within the Java Standard Edition Development Kit (JDK). It’s an essential tool for developing in Java on any platform.

The JDK is not the same as the Java Runtime Environment (JRE), which you’ll already have installed if you’ve ever used a Java application on your machine.

1. Download the JDK from Oracle’s website – the Windows version. Download any of the following: an x64 installer (shown in the screen), an x64 compressed archive, or an x64 MSI installer.

Note: if you have just simple use for Java software, make sure you do not download the “Java SE Development Kit for Java SE subscribers,” which is on the same download page. If you wish to use Java’s JRE installation for Microsoft Windows, it has been moved to another page.

1. Note the Windows location where Java is being installed. It will come in handy later when you’re trying to run Java from the Command Prompt.

1. The installation should be over in just a few seconds. If it is taking a long time, close all of your other apps from Task Manager and reinstall the software.

Running a Java Program From the Command Prompt

public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } }

1. Use the cd command to change your working directory to the directory containing your Java program. To know which directory to go to, check the saved location of Java on your PC as discussed above.

cd Documents[Java-program-folder]

1. From here, locate the path to the version of the Java Development Kit (JDK) on your computer. For example, if you’re running 64-bit Windows, that will often be in “C:\Program Files\Java.”

set path=%path%;C:\Program Files\Java\jdk-"Java Version Number".bin

1. You may need to change the directory path to reflect the current version of Java. Make sure you’re using the Java Development Kit (JDK) directory and pointing to the “bin” folder.

Note: the Java Runtime Environment (JRE) folder also contains a “bin” folder but doesn’t hold the Java compiler. If you get errors around the compilation, make sure you’re using the correct directory path.

1. Compile the Java program with the javac command as shown below. Be warned that you won’t see anything happen. However, if you use the dir command, you’ll notice a new file in your directory ending in the “.class” extension, indicating the program has been compiled.

You’ll see the program run within the Command Prompt window, but there’s one more task you can do to make sure your Java program runs smoothly: set your path.

Setting a Permanent PATH

The above command doesn’t set your Java compiler PATH permanently. It sets the environment variable for that session, but that change will be wiped away when you close the Command Prompt session.

Setting your Java compiler PATH permanently can come in handy if you want your compiled Java programs to run smoothly after a PC reboot. This helps launch the requested programs quickly from the Command Prompt window (or a third-party software like Eclipse).

Follow the steps below to change your PATH variable for all future sessions.

1. Click the “Environment Variables” button at the bottom after you’ve switched to the “Advanced” tab in the “System Properties” window.

1. Paste the directory path you used above into the text box. Again, make sure you’re using the Java Development Kit (JDK) directory and not the Java Runtime Environment (JRE) directory next to it.

This article featured a simple Java program, but you can initiate almost any Java program from the Command Prompt. The procedure is straightforward regardless of the nature of your program.

Frequently Asked Questions

How can I fix «You don’t have permission to save in this location» while saving Java files?

Some users may get a “You don’t have permission to save in this location” error while saving Java files in Windows. Even though you are the administrator of your PC, this error shows up out of nowhere. To fix the problem, right-click the Java folder’s “Properties” and navigate to the “Security -> Advanced -> Select User or Group.”

In the “Advanced Security” settings for Java, change the “Owner” from “System” to whatever user account you have used to log in to the device. You can determine the correct name from “Check names.” Just enter the text, such as “Desktop,” “Administrator,” or “Users,” to enable full permissions to the folder. Click “OK” and save the changes.

How can I fix «Java is not recognized as an internal or external command» in Windows?

The best way to fix “Java is not recognized as an internal or external command” is to add Java’s bin directory to your computer’s path, as covered above.

Windows Command Prompt doesn’t show the results of Java command. How can I fix it?

If your Windows Command Prompt doesn’t show the results of a Java command you’ve entered, there are two solutions: run the Command Prompt in Administrator Mode or find your “Java.exe” file in the folder location and open its “Properties.” Then, navigate to the “Compatibility” tab where you will have to uncheck the “Run this program as an administrator” option.

What is the difference between Java and Javascript?

Don’t confuse Java with Javascript, as they are two different entities:

• Java came before Javascript. It was founded by Sun Microsystems in 1991-1995. Javascript was founded later by Netscape, an old browser company. Basically, Javascript is a very lightweight version of Java and still commonly used in browsers.
• Java is a compiled program, whereas Javascript is interpreted.
• Java is a static typed program, whereas Javascript is dynamically typed.
• Java uses classes, and Javascript uses prototypes.

Image credit: WrightStudio via AdobeStock. All screenshots by Sayak Boral.

Sayak Boral is a technology writer with over eleven years of experience working in different industries including semiconductors, IoT, enterprise IT, telecommunications OSS/BSS, and network security. He has been writing for MakeTechEasier on a wide range of technical topics including Windows, Android, Internet, Hardware Guides, Browsers, Software Tools, and Product Reviews.

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