Create a new file in your text editor or IDE named HelloWorld.java
. Then paste this code block into the file and save:
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
Note: For Java to recognize this as a public class
(and not throw a compile time error), the filename must be the same as the class name (HelloWorld
in this example) with a .java
extension. There should also be a public
access modifier before it.
Naming conventions recommend that Java classes begin with an uppercase character, and be in camel case format (in which the first letter of each word is capitalized). The conventions recommend against underscores (\\_
) and dollar signs ($
).
To compile, open a terminal window and navigate to the directory of HelloWorld.java
:
cd /path/to/containing/folder/
Note: cd is the terminal command to change directory.
Enter javac
followed by the file name and extension as follows:
$ javac HelloWorld.java
It’s fairly common to get the error 'javac' is not recognized as an internal or external command, operable program or batch file.
even when you have installed the JDK
and are able to run the program from IDE
ex. eclipse
etc. Since the path is not added to the environment by default.
In case you get this on windows, to resolve, first try browsing to your javac.exe
path, it’s most probably in your C:\\Program Files\\Java\\jdk(version number)\\bin
. Then try running it with below.
$ C:\\Program Files\\Java\\jdk(version number)\\bin\\javac HelloWorld.java
Previously when we were calling javac
it was same as above command. Only in that case your OS
knew where javac
resided. So let’s tell it now, this way you don’t have to type the whole path every-time. We would need to add this to our PATH
To edit the PATH
environment variable in Windows XP/Vista/7/8/10:
You cannot undo this so be careful. First copy your existing path to notepad. Then to get the exact PATH to your javac
browse manually to the folder where javac
resides and click on the address bar and then copy it. It should look something like c:\\Program Files\\Java\\jdk1.8.0_xx\\bin
In “Variable value” field, paste this IN FRONT of all the existing directories, followed by a semi-colon (;). DO NOT DELETE any existing entries.