等待多个期货的回调

最近我使用API​​深入研究了一些工作.API使用Unirest http库来简化从Web接收的工作.当然,由于从API服务器调用数据,我试图通过使用API​​的异步调用来提高效率.我的想法结构如下:

通过返回期货结果来创建数据数组

显示数据+从数据中收集的其他信息

因此,在开始第二步之前,我需要返回所有数据.我的代码如下:

Future < HttpResponse < JsonNode >  > future1 = Unirest.get("https://example.com/api").asJsonAsync(new Callback < JsonNode > () {
    public void failed(UnirestException e) {
        System.out.println("The request has failed");
    }
    public void completed(HttpResponse < JsonNode > response) {
        System.out.println(response.getBody().toString());
        responses.put(response);
    }
    public void cancelled() {
        System.out.println("The request has been cancelled");
    }
});
Future < HttpResponse < JsonNode >  > future2 = Unirest.get("https://example.com/api").asJsonAsync(new Callback < JsonNode > () {
    public void failed(UnirestException e) {
        System.out.println("The request has failed");
    }
    public void completed(HttpResponse < JsonNode > response) {
        System.out.println(response.getBody().toString());
        responses.put(response);
    }
    public void cancelled() {
        System.out.println("The request has been cancelled");
    }
});
doStuff(responses);

我怎样才能这样做,只有在两个期货完成后才会调用doStuff？