How to create a request mapping dynamically

Question

I need to create a mapper object based on the input type, is there a simple solution without switch case or if else conditions? Below is an example. Can you please help me to provide a simple working example for this?

Mapper mapper = null;
if(requestType=="AAA"){
    mapper = RequestMapperAAA.createTypeRequest(inputpayload);
} else if(requestType=="BBB"){
    mapper = RequestMapperBBB.createTypeRequest(inputpayload);
} else if(requestType=="CCC"){
    mapper = RequestMapperCCC.createTypeRequest(inputpayload);
} else if(requestType=="DDD"){
    mapper = RequestMapperDDD.createTypeRequest(inputpayload);
}  so on.. upto 20 input types

Answer 1

I will give a more detailed answer here, by responding to you question about using reflection. There is a good example here if you want to use reflection.

You don't have to implement reflection to do this. The response of @Thiyadu is good also. Instead if you want to use factory pattern with reflection, I will suggest you to use a Dependency Injection framework such as Spring. The reflection phase is already made for you by Spring.

An example with Spring will be the following:

public interface Mapper {
    
}

RequestMapperAAA.java

@Component("AAA")
public class RequestMapperAAA implements Mapper {

}

RequestMapperBBB.java

@Component("BBB")
public class RequestMapperBBB implements Mapper {

}

RequestMapperCCC.java

@Component("CCC")
public class RequestMapperCCC implements Mapper {

}

Usage:

@Autowired
private Map<String, Mapper> requestMapper;

public void userRequestMapper() {
    Mapper requestAAA = requestMapper.get("AAA");
}

The good thing about Spring is that, it will automatically populate the Map for you.