RequestBuilder returning null

I have the following problem.

I created a class to take care of all calls to a database. I'm using RequestBuilder on the front end of GWT to send a HTTP GET r开发者_如何学Pythonequest.

public String getDadosGET(String phpFilePath) {
    rb = new RequestBuilder(RequestBuilder.GET, phpFilePath);
    rb.setHeader(header, headerValue);

    try {
        response = rb.sendRequest(null, new RequestCallback() {

            @Override
            public void onResponseReceived(Request request, Response response) {
                text = response.getText();                  
            }

            @Override
            public void onError(Request request, Throwable exception) {

            }
        });
    } catch (RequestException e) {
        e.printStackTrace();
    }
    return text;
}

Now If I output the text inside the onResponseReceived method, It's not null. If done right before return text, it's null.

What I need is to force the program to get the data first, then return the method.

Thanks.

---

I think you haven't quite understood the concept of asynchronous calls. Check out the this article.

I don't think there's a way of making a GWT call synchronously, which is what you seem to want.