Java泛型 创建实例

1. 工厂模式在泛型中创建实例

   interface FactoryI {
   	T create();
   }
   
   class Foo {
   	private T x;
   
   	public > Foo(F factory) {
   		x = factory.create();
   	}
   }
   
   // 对于不是自己定义的Java对象创建
   class IntegerFactory implements FactoryI {
   
   	@Override
   	public Integer create() {
   		return new Integer(0);
   	}
   }
   
   // 自定义的对象可以添加内部工厂方法或者内部工厂类
   class Widget {
   	public static class Factory implements FactoryI {
   
   		@Override
   		public Widget create() {
   			return new Widget();
   		}
   
   	}
   }
   
   public class FactoryConstraint {
   	public static void main(String[] args) {
   		new Foo(new IntegerFactory());
   		new Foo(new Widget.Factory());
   	}
   }

    
2. 模板方法方式

   abstract class GenericWithCreate {
   	final T element;
   
   	public GenericWithCreate() {
   		element = create();
   	}
   
   	abstract T create();
   }
   
   class X {
   
   }
   
   class Creator extends GenericWithCreate {
   	@Override
   	X create() {
   		return new X();
   	}
   
   	void f() {
   		System.out.println(element.getClass().getSimpleName());
   	}
   
   }
   
   public class CreatorGeneric {
   	public static void main(String[] args) {
   		Creator creator = new Creator();
   		creator.f();
   	}
   }