static 方法的通用类型

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);
        }
    }
}

Answer 1

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 {

    /* ... */
}

Answer 2

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);
        }
    }
}