SE450: Horstmann Chapter 1: "Hello, World" in Java

Construct separate class to test your class
main method is called when program starts
main is static: it doesn't operate on any objects
There are no objects yet when main starts
In OO program, main constructs objects and invokes methods

file:horstmann/ch01_helloworld/GreeterTester.java [source] [doc-public] [doc-private]

package horstmann.ch01_helloworld;
public class GreeterTester
{
  public static void main(String[] args)
  {
    Greeter worldGreeter = new Greeter("World");
    String greeting = worldGreeter.sayHello();
    System.out.println(greeting);
  }
}

file:horstmann/ch01_helloworld/Greeter.java [source] [doc-public] [doc-private]

package horstmann.ch01_helloworld;
/**
   A class for producing simple greetings.
 */

public class Greeter
{
  /**
      Constructs a Greeter object that can greet a person or
      entity.
      @param aName the name of the person or entity who should
      be addressed in the greetings.
   */
  public Greeter(String aName)
  {
    name = aName;
  }

  /**
      Greet with a "Hello" message.
      @return a message containing "Hello" and the name of
      the greeted person or entity.
   */
  public String sayHello()
  {
    return "Hello, " + name + "!";
  }

  private String name;
}