Interface implementation dependency resolver

[Pratap koritala]

Hi,

There are some Interfaces and implementation classes.
Some classes would be having dependency on the interface implementation,
If it would have been spring Framework, It will find the interface implementation and assigns implementation class to it.

In the following Spring will find Ishape implementation and assigns it to IShape.

class A{
  private IShape shape;
  
  @autowired
   A(IShape shape){
      this.shape = shape;
   }
}

Without Spring,

I need to declare like,

Class A{
  private IShape shape;

   A(){
      this.shape = new ShapeImpl();
   }
}

But, the above code is having actual implementation this.shape = new ShapeImpl(); class with-in the code. Is there a way to do without spring using plain java.

Something,like this.shape = createObject(IShape.class) . But,haven't got good Idea about implementation of createObject.

Any help would be appreciated.

[David Newton]

Sure, use a factory, or create an object using forName()/newInstance(), or...

[Pratap koritala]

createObject need to find the implementation class of the interface and then intailize.
Intailizing from classname is fine,But I can't able to find API for finding interface implementaiton class

Can you elaborate more on factory?

Thanks for reply,I would be searching on factory pattern.