new Java Generic class constructor issue when templete class nested

Question

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I have below define :

JsonResponse.class as below:

public abstract class JsonResponse<T> extends AbstractResponse {
private T jsonObject;

public JsonResponse(HttpResponse httpResponse, Class<T> classT) {
    super(httpResponse);
    jsonObject = new Gson().fromJson(
            ResponseUtils.getStringContent(getHttpResponse()), classT);
}

public T getJsonObject() {
    return jsonObject;
}

}

But below class i want to new and return as:

return new JsonResponse<T>(response, classT);

but I can't compile it with error, would you please take a look at it . Thank you .

public class JsonResponseHandler<T> implements ResponseHandler<JsonResponse<T>> {

private Class<T> classT;

public JsonResponseHandler(Class<T> classT) {
    this.classT = classT;

}

@Override
public JsonResponse<T> handleResponse(HttpResponse response)
        throws ClientProtocolException, IOException {

    return new  JsonResponse<T>(response, classT) ; //compile  always error
}

}

What? Anyways, `JsonResponse` class is abstract. You can't instantiate it. That is where the error is. — Rohit Jain, Oct 12 '13 at 11:41
It's so my mistake , I am so careless , Thank you very much , Because of this error , I even guess it can't supported by my design . Thank you again . — Jerry Cai, Oct 12 '13 at 11:44
As a compute programmer , It is more quick than using Google to search related strange technology issue that Using Stackoverflow to ask . — Jerry Cai, Oct 12 '13 at 11:52
@JerryCai It may be more convenient, but reading the compiler error would have clued you in relatively quickly as well. — nanofarad, Oct 12 '13 at 11:59

score 0 · Answer 1 · answered Oct 12 '13 at 11:59

public JsonResponse<T> handleResponse(HttpResponse response)
    throws ClientProtocolException, IOException {

return new  JsonResponse<T>(response, classT) ; //compile  always error
}

2 issues:

JsonResponse is abstract.

You're constantly redeclaring the genericism:

public JsonResponse handleResponse(HttpResponse response)
throws ClientProtocolException, IOException {

    return new  JsonResponse(response, classT) ; //compile  always error
}

It's already generic and should have reifiable type params.

new Java Generic class constructor issue when templete class nested

1 Answers1