| The first bold line in the following listing begins a class definition block. |
| /** * The HelloWorldApp class implements an application that * simply displays "Hello World!" to the standard output. */ class HelloWorldApp { public static void main(String[] args) { System.out.println("Hello World!"); //Display the string. } } |
| A class--the basic building block of an object-oriented
language such as Java--is a template that describes the data and behavior associated with instances of that class. The data associated with a class or object is stored in variables; the behavior associated with a class or object is implemented with methods. Methods are similar to the functions or procedures in procedural languages such as C. In the Java language, the simplest form of a class definition is |
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| class name { . . . } |
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| The keyword class begins the class definition for a class named name. | |
| The variables and methods of the class are embraced by the curly brackets that begin and end the class definition block. The "Hello World" application has no variables and has a single method named main. | |
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