What is a factory method? when to use this concept?

Question

Could any oneplease describe what a factory method is and explain how I can use it by giving a simple example?

Answer 1

Instead of instantiating a class all over your program you do it in one method that's part of the class. This means the class gets control over the instantiating process, a factory.
1. You can implement a dispose facility, that is giving back objects that can be reused (when the factory method is called an old object is returned if there is one in store, only if not a new one is instantiated).
2. An abstract class can have a factory method that returns concrete classes on demand, like
abstract class Hello {
   static newHello(int id) {  // factory method
      switch (id) {
      case 0: return new Hi();
      case 1: return new Howdy();
      return null;
public class Hi extends Hello {
public class Howdy extends Hello {