Compiling the Program
To compile the Example program, execute the compiler, javac, specifying the name of the source file on the command line, as shown here:
C:\>javac Example.java
The javac compiler creates a file called Example.class that contains the bytecode version of the program. As discussed earlier, the Java bytecode is the intermediate representation of your program that contains instructions the Java Virtual Machine will execute. Thus, the output of javac is not code that can be directly executed.
To actually run the program, you must use the Java application launcher, called java.To do so, pass the class name Example as a command-line argument, as shown here:
C:\>java Example
When the program is run, the following output is displayed:
This is a simple Java program.
When Java source code is compiled, each individual class is put into its own output file named after the class and using the .class extension. This is why it is a good idea to give your Java source files the same name as the class they contain—the name of the source file will match the name of the .class file. When you execute java as just shown, you are actually specifying the name of the class that you want to execute. It will automatically search for a file by that name that has the .class extension. If it finds the file, it will execute the code contained in the specified class.
