调用两个不同类的相同方法

Question

I'm using some classes that I can't modify :

• GenericRequest
• SpecificRequest1 (extends GenericRequest)
• SpecificRequest2 (extends GenericRequest)

Both of the SpecificRequest classes share a lot of method (but these method are not declared in GenericRequest, I know this is bad but I just can't change this).

I would like to create a method like this one (to factorize as much as possible):

private void fillRequest( GenericRequest p_request, boolean p_specificModeOne ) {
    if( p_specificModeOne ) {
        SpecificRequest1 l_specificRequest = (SpecificRequest1) p_request;
    }
    else {
        SpecificRequest2 l_specificRequest = (SpecificRequest2) p_request;
    }

    l_specificRequest.commonMethod1();
    l_specificRequest.commonMethod2();
}

I know this is not valid Java, but that is the idea. Do you think it would be possible to do something clean with this ? Or I have to create two different methods to handle both SpecificRequest1 and SpecificRequest2 ?

Answer 1

This is a well-known pattern Adapter. The code could look like this:

class GenericRequest {}

class SpecificRequest1 extends GenericRequest {
    void method1() {
        System.out.println("specific1");
    }
}

class SpecificRequest2 extends GenericRequest {
    void method2() {
        System.out.println("specific2");
    }
}

interface ReqInterface {
    void method();
}

class Specific1 implements ReqInterface {
    private final SpecificRequest1 req =new SpecificRequest1();

    @Override
    public void method() {
        req.method1();
    }
}

class Specific2 implements ReqInterface {
    private final SpecificRequest2 req =new SpecificRequest2();

    @Override
    public void method() {
        req.method2();
    }
}

public class Production {
    void method(ReqInterface req) {
        req.method();
    }

    public static void main(String[] args) {
        Production l3 = new Production();
        l3.method(new Specific1());
        l3.method(new Specific2());
    }
}

Try to avoid any booleans in method parameters and instanceof at any cost ))