Generic type for static method

Question

Is there a way I can make the static method toObject generic by passing the T class and return type T?

public class JsonUtil { private JsonUtil() { } public static Object toObject(String jsonString, Class clazz, boolean unwrapRootValue) throws TechnicalException { ObjectMapper mapper = new ObjectMapper(); mapper.writerWithDefaultPrettyPrinter(); if (unwrapRootValue) mapper.enable(DeserializationFeature.UNWRAP_ROOT_VALUE); try { return mapper.readValue(jsonString, clazz); } catch (IOException e) { throw new TechnicalException("Exception while converting JSON to Object", e); } } }

JsonConverter would be a much better name for your class than JsonUtil. “Util” says nothing about what a class does. — VGR
– VGR, Commented Sep 23, 2019 at 4:23

Robby Cornelissen · Accepted Answer · 2019-09-23 04:19:48Z

Sure. Just specify a generic type parameter on the method itself, and use it for both the return type and the clazz parameter:

public static <T> T toObject(String jsonString, Class<T> clazz, boolean unwrapRootValue) throws TechnicalException { /* ... */ }

i.bondarenko · Accepted Answer · 2019-09-23 05:10:41Z

public class JsonUtil { private JsonUtil() { } public static <T> T toObject(String jsonString, Class<? extends T> clazz, boolean unwrapRootValue) throws TechnicalException { ObjectMapper mapper = new ObjectMapper(); mapper.writerWithDefaultPrettyPrinter(); if (unwrapRootValue) mapper.enable(DeserializationFeature.UNWRAP_ROOT_VALUE); try { return mapper.readValue(jsonString, clazz); } catch (IOException e) { throw new TechnicalException("Exception while converting JSON to Object", e); } } }

I see you removed Class<? super T>, however, Class<? extends T> might actually be useful. I haven't thought it through enough to determine if it would have any utility when casting toObject as a method reference.
No need to cast the result of mapper.readValue(). It's already generic.

Collectives™ on Stack Overflow

Generic type for static method

2 Answers 2

Comments

3 Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

3 Comments

Related