Factory Method

A design method that involves creating objects of unknown type, later resolved within the class. Often done when you want to provide the option to instantiate two classes that are very similar.

Example

class Triangle extends Shape{
}
class Circle extends Shape{
}
 
abstract class GraphicsApplication{
	List<Shape> shapes;
	public abstract Shape factoryMethod();
	public void addShape(){
		Shape s = factoryMethod();
		shapes.add(s)
	}
}
 
public class CirclesApplications extends GraphicsApplication{
	public Shape createShape(){
		return new Circle();
	}
}
 
public class TrianglesApplicatiion extends GraphicsApplication{
	public Shape createShape(){
		return new Triangle();
	}
}
 
public class App{
	public static void main(String [] args){
		TrianglesApplication app = new TrianglesApplication();
		app.addShape();
	}
}