Compiling and Running Java Programs

∟Compiling and Running Java Programs

This section describes a tutorial example on how to compile and run Java programs.

When JDK is installed on your machine, it provides two commands for you to compile and run Java programs.

"javac class_name.java" - Compiles a Java program stored a file named with the program class name.
"java -cp . class_name" - Runs a compiled Java program. "-cp ." specifies the current directory as the class path.

Or you can just use "java class_name.java" command to compile and run a Java program in a single command. This feature is supported since JDK 9.

Let's try these commands with a very simple Java program. Use NotePad to enter the following Java program into a file called Hello.java:

class Hello {
   public static void main(String[] a) {
      System.out.println("Hello world!");
   }
}

Then compile this program in a command window with the "javac" command:

herong$ javac Hello.java

To execute the program, use the "java" command:

herong$ java Hello
Hello world!

Or compile and execute the program in a single command:

herong$ java Hello.java
Hello world!

Congratulations, you have successfully entered, compiled and executed your first Java program.

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