How to get a value from a generic Object

Question

I have the following request with these fields:

Payment (Type Payment) -> Parameters (Type Object). I know this Parameters class has these fields:

token (String)
type (String)
cvv (String)

I´m trying to have access to the field token through request.getPayment().getParameters() but I don't really know how to make it work. I found something related to Reflection but I don´t really know how it can work.

I've tried something like but I still don't know howo to fetch this String "token":

 Field field = org.springframework.util.ReflectionUtils.findField(String.class, "token"); org.springframework.util.ReflectionUtils.makeAccessible(field); String token = field.get(request.getPayment().getParameters().????) ????

If the class has these fields then it must provide some way to access them, surely? — Ross Drew
– Ross Drew, Commented Aug 6, 2020 at 21:38

Szymon Dudziak · Accepted Answer · 2020-08-06 14:20:28Z

If you sure that you will always have these fields in this generic object, you can just use casting:

class PaymentParameter { String token; String type; String cvv; ... // getters & setters or Lombok stuff } ... var paymentParameters = (PaymentParameters) request.getPayment().getParameters();

You can read more about casting here and here.

Please be aware that casting can throw ClassCastException. So you have to cover this case in your code.

The second option is that your request is a JSON string, then you can use Jackson to convert it to the map or object. This topic is covered also on Baeldung.

I know that, but I don´t want to create a new class if possible.
In that case please check this anwser: stackoverflow.com/a/16172206/1110241

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