Cmd java file path

How to Set Path and Classpath in Java

Java PATH and Java CLASSPATH are two confusing environment variables for Java beginners. Both are operating system level Environment Variables.

What are Environment Variables ?

Many operating systems use environment variables to pass configuration information to applications. Java environment variables are key/value pairs, where both the key and the value are strings. There are many subtle differences between the way environment variables are implemented on different Operating Systems. For example, Variables in Windows are NOT case-sensitive , while UNIX does not. The way environment variables are used also varies. Environment variables are typically named in uppercase, with words joined with underscore such as: JAVA_HOME .

Environment Variables examples

JAVA_HOME : C:\Program Files\Java\jdk1.8.0 JDK_HOME : %JAVA_HOME% JRE_HOME : %JAVA_HOME%\jre CLASSPATH : .;%JAVA_HOME%\lib;%JAVA_HOME%\jre\lib PATH : your-unique-entries;%JAVA_HOME%\bin

Many problems in the installation and running of Java applications are caused by incorrect setting of environment variables especially in confoguring PATH, CLASSPATH and JAVA_HOME.

How to set Java path in Windows

Java PATH is the environment variable where we specify the locations of binaries. When you run a program from the command line, the operating system uses the PATH environment variable to search for the program in your local file system. In Java, for run any program we use ‘java.exe’ and for compile java code use javac.exe . These all executable(.exe) files are available in bin folder so we set path up to bin folder. The Operating System will look in this PATH for executable. You can set the path environment variable temporary (command line) and Permanent.

Set path from Windows command line (CMD)

Open command prompt and type the following on command prompt.

Set Permanent Path of Java in Windows

In Windows inorder to set

1. Step 1: Right Click on MyComputer and click on properties

1. Step 2: Click on Advanced System Setting

1. Step 3: Select Advanced Tab and Click on Environment Variables

1. Step 4: Then you get Environment Variable window and Click on New.

Then you get a small window «New System Variable» and there you can set «Variable Name» and «Variable Value». Set Variable Name as «path» and Variable Value as «your jdk path».

Click «OK» button. Now you set your Java Path and next is setting up ClassPath.

How to Set Classpath for Java on Windows

Java CLASSPATH is the path for Java application where the classes you compiled will be available. It is a parameter in the Java Virtual Machine or the Java compiler that specifies the location of user-defined classes and packages. The parameter may be set either on the command-line, or through an environment variable. If CLASSPATH is not set, it is defaulted to the current directory. If you set the CLASSPATH , it is important to include the current working directory (.). Otherwise, the current directory will not be searched.

In Windows inorder to set ClassPath :

Repeat the above steps: Steps1 to Step4 .

Then you get a small window «New System Variable» and there you can set «Variable Name» and «Variable Value». Set Variable Name as «ClassPath» and Variable Value as «your class path» (ex: C:\Program Files\Java\jdk1.8.0\lib\* ).

Using wildcards in java classpath

Wild cards were introduced from Java 6 . Class path entries can contain the basename wildcard character *, which is considered equivalent to specifying a list of all the files in the directory with the extension .jar or .JAR. For ex. a classpath entry consisting simply of * expands to a list of all the jar files in the current directory.

Example

where %MAINCLASS% is the class containing your main method.

How to use a wildcard in the classpath to add multiple jars

where %MAINJAR% is the jar file to launch via its internal manifest.

If you need only specific jars, you will need to add them individually. The classpath string does not accept generic wildcards like Jar*, *.jar, hiber* etc.

Example

The following entry does not work:

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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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