Question

I have figured out that my GSON problems are all about the fact that, while my return type is not a parameterized object, it should have been. Now I need to use the Gson.fromJson method with the type of parameter to specify the return type so that GSON will take care of it for me.

I have created a generic class called RestResponse such:

public class RestResponse<T> {
  private   String      errorMessage;
  private   int         errorReason;
  private   T           result;

  /* (non-Javadoc)
   * @see java.lang.Object#toString()
   */
  @Override
  public String toString() {
    return "RestResponse [errorMessage=" + errorMessage + ", result=" + result + "]";
  }

  /**
   * Does this response contain an error?
   * @return true if in error
   */
  public boolean isInError(){
    return getErrorMessage()!=null;
  }

  /**
   * @return the errorMessage
   */
  public String getErrorMessage() {
    return errorMessage;
  }

  /**
   * @param errorMessage the errorMessage to set
   */
  public void setErrorMessage(String errorMessage) {
    this.errorMessage = errorMessage;
  }

  /**
   * The error reason code
   * @return the errorReason
   */
  public int getErrorReason() {
    return errorReason;
  }

  /**
   * The error reason code
   * @param errorReason the errorReason to set
   */
  public void setErrorReason(int errorReason) {
    this.errorReason = errorReason;
  }

  /**
   * The result of the method call
   * @return the result or null if nothing was returned
   */
  public final T getResult() {
    return result;
  }

  /**
   * The result of the method call
   * @param result the result to set or null if nothing was returned
   */
  public final void setResult(T result) {
    this.result = result;
  }
}

Now I want to create the resulting type on the other side. I have a generic method that I use to decode these things and either throw the exception or return the result.

So my method is like this:

public Object submitUrl(String url, Class<?> clazz) throws AjApiException {

Where clazz is the type that will be specified on RestResponse.

I then go to create the RestResponse before passing to GSON:

Type typeOfT = new TypeToken<RestResponse<clazz>>(){}.getType(); //1-->What goes here?
RestResponse<clazz> restResponse; //2-->and here?

And it errors. Can someone tell me what goes in these to places in place of clazz?

Answer 1

I ended up passing in the type instead of the class. This solved the problem.

I believe you can create the type by doing something like:

Type typeOfT = new TypeToken<RestResponse<T>>(){}.getType();