设计模式：工厂

1. JUST LIKE A CONTRACT HERE

// abstract 
public interface IProduct {
	void doSomething();
}

// real product 
public class ProductA implements IProduct {
	public void doSomething(){
	 // ...
	}
}
// real product 
public class ProductB implements IProduct {
	public void doSomething(){
	 // ...
	}
}

2. FACTORY

public class Creator {
	public static IProduct factory(String product) {
		if (product.equals('a')) {
			return new ProductA();
		}
		else if(product.equals('b')) {
			return new ProductB();
		}
	}
}

3. CLIENT

public class Consumer{
	public static void main(String[]] args) {
		Creator creator = new Creator();
		IProduct product = creator.factory(args[0]);
		//then consumer start using this product
		product.doSomething();
	}
}