title: RxJava : How to handle error with zip operator ?
body: <p>I am using RxJava and RxAndroid with Retrofit2.</p>
  
  <pre><code>Observable&lt;ResponseOne&gt; responseOneObservable = getRetrofitClient().getDataOne()
  .subscribeOn(Schedulers.io())
  .observeOn(AndroidSchedulers.mainThread());
  
  Observable&lt;ResponseTwo&gt; responseTwoObservable = getRetrofitClient().getDataTwo()
  .subscribeOn(Schedulers.io())
  .observeOn(AndroidSchedulers.mainThread());
  </code></pre>
  
  <p>Using zip operator as below on above two Observer. </p>
  
  <pre><code> Observable&lt;ArrayList&lt;TestData&gt;&gt; testDataObservable = Observable.zip(responseOneObservable, responseTwoObservable, new Func2&lt;ResponseOne, ResponseTwo, ArrayList&lt;TestData&gt;&gt;() {
              @Override
                  public ArrayList&lt;TestData&gt; call(ResponseOne responseOne, ResponseTwo responseTwo) {
                    ArrayList&lt;TestData&gt; testDataList = new ArrayList();
                        // Add test data from response responseOne &amp; responseTwo
                    return testDataList;
              } 
      })
      .subscribeOn(Schedulers.io())
      .observeOn(AndroidSchedulers.mainThread())
      .subscribe(new Subscriber&lt;ArrayList&lt;TestData&gt;&gt;() {
  
          @Override
          public void onNext(ArrayList&lt;TestData&gt; testDataList) {
  
          }
  
          @Override
          public void onCompleted() {
              Log.d(TAG, "onCompleted" );
          }
  
          @Override
          public void onError(Throwable t) {
              Log.d(TAG, "onError Throwable: " + t.toString() );
          }
      });
  </code></pre>
  
  <p>If there is any error occurs during retrofit http call in  <code>responseOneObservable</code> and <code>responseTwoObservable</code> then it will directly call <code>onError</code> method of subscriber of <code>testDataObservable</code>.</p>
  
  <p>I want to continue in zip operator's <code>call</code> method even if anyone of two observable got success response.</p>
  
  <p>How to handle error response using <code>zip</code> operator ? </p>