Compiling and Running Hello World

To make sure your Java environment is correctly configured, bring up a command-line prompt and type


If your computer responds with

error: Can't read:

you're ready to begin. If, on the other hand, it responds

javac: Command not found

or something similar, then you need make sure you have the Java environment properly installed and your PATH configured.

Assuming that Java is properly installed on your system there are three steps to creating a Java program:

  1. writing the code
  2. compiling the code
  3. running the code

Under Unix, compiling and running the code looks like this:

$ javac
$ java HelloWorld
Hello World

Under Windows, it's similar. You just do this in a DOS shell.

C:> javac
C:> java HelloWorld
Hello World

Notice that you use the .java extension when compiling a file, but you do not use the .class extension when running a file.

For IDEs, consult your product documentation.

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Copyright 1997-2006 Elliotte Rusty Harold
Last Modified February 3, 2004