How to Compile & Run Java Program Using Command Prompt
While many programming environments will allow you to compile and run a program within the environment, you can also compile and run using Command Prompt. Both Windows and Mac have their own versions of Command Prompt, although it is...
Method 1 of 2:
Compiling and Running
- Save the program. After using a text editor, such as NotePad, to create your Java program, save the program with a .java extension. Of course, the file name can be anything. For the purposes of this tutorial, "filename" will be used as a placeholder for your file name.
- To ensure that your file is saved as a .java file, be sure to write .java after the file name, and select All Files from the dropdown extension menu.
- Make note of where you saved the file on your system.
- If you are unsure of how to write a program in Java, check out our tutorial on how to program in Java. For the purposes of learning how to compile and run a program, though, you can use any sort of Java program.
- Open Command Prompt/Terminal. Accessing the command line differs slightly for Mac and Windows.
- Windows: Press ⇱ Home, then type cmd. Press ↵ Enter to open the Command Prompt.
- Mac: In Finder, press the Go tab, select Applications, select Utilities, then select Terminal.
- Check that Java is installed. Type
java -version
into your command line. If java is installed, you will see a message stating what version of Java is currently installed.- If not, you may need to install the Java Development Kit from their website. It is free and can be found at this link: http://www.oracle.com/technetwork/java/javase/downloads/index.html.
- Navigate to the correct folder. Use the command cd followed by the directory name to change your working directory.
- For example, if you were operating in
C:UsersBobProject
and wanted to get toC:UsersBobProjectTitanProject
, enter incd TitanProject
and press ↵ Enter. - You can see a list of what is in your current directory by typing
dir
and pressing ↵ Enter.
- For example, if you were operating in
- Compile the program. Once you are in the correct directory, you can compile the program by typing
javac filename.java
into the command line and pressing enter.- If you have any errors in your program, or if there is difficultly compiling, the command prompt will notify you.
- Check out our article about how to fix compiler errors in Java for more help.
- Run the program. Enter in
java filename
and press ↵ Enter. Of course, replace "filename" with whatever the name of your file actually is.- After pressing ↵ Enter, your program should run. If you receive an error, or if your program fails to run in any way, refer to the troubleshooting method.
Method 2 of 2:
Troubleshooting
- Set your path. If you are running a simple program with all of the files in the same directory, you will probably not need to do this. However, if you are running a more complex program with files in multiple directories, you will need to tell the computer where to look for these files.
- Windows: Type
java -version
into the command prompt and press ↵ Enter. Based off the version of Java displayed on the first line, type inset path=%path%;C:Program FilesJavajdk1.5.0_09bin
to the command prompt and press ↵ Enter. Substitute jdk1.5.0_09 with whatever version of Java you have installed.- Be sure you are entering in this command while in the directory containing your Java project.
- Mac: Type
/usr/libexec/java_home -v 1.7
into the terminal and press ↵ Enter to ensure Java is installed on your system. Then, typeecho export "JAVA_HOME=$(/usr/libexec/java_home)" >> ~/.bash_profile
into the terminal and press ↵ Enter. Restart the terminal afterwards.
- Windows: Type
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