Java异步调用方法等待返回

Question

我知道可能有几种方法可以做到这一点，只是寻找最有效和最简洁的方法:

public Object giveMeNewObject() {
    final Object result = null;
    SomeApiClient.start(new Callback() { // starts an async process
        @Override
        public void onSuccess(Object somethingNew) {
            result = somethingNew; //ERROR; can't set cause final
        }
    });
    return result; //result is null, cause Async already finished
}

Answer 1

从您的代码中 - 这是动态修改的，因此纠正错误，一切都会按您的预期工作 - 调用者将等到第 3 方完成处理并获得该过程的结果:

public Object giveMeNewObject() {
    CountDownLatch latch=new CountDownLatch(1);
    Callback callback=new Callback() { 
      public sometype result=null;
        @Override
        public void onSuccess(Object somethingNew) {
            result = somethingNew; //ERROR; can't set cause final
            latch.countDown();
        }
    });
    SomeApiClient.start(callback);
    latch.await(sometimetowait);
    return callback.result;

}