How to Compile & Run Java Program Using Command Prompt

Compiling and Running

1. 
   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.
2. 
   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.
3. 
   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.
4. 
   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 to C:UsersBobProjectTitanProject , enter in cd TitanProject and press ↵ Enter.
   • You can see a list of what is in your current directory by typing dir and pressing ↵ Enter.
5. 
   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.
6. 
   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.