title: RxJava filter operator
body: <p>I am new in rxJava.</p>
  
  <p>Well, I was testing few examples to integrate operators in rxJava.
  So, I have a problem with this:</p>
  
  <pre><code>    Observable.just("JUAN", "LUCILA", "ARMANDO").map(new Function&lt;String, Integer&gt;() {
          @Override
          public Integer apply(String s) throws Exception {
              return s.length();
          }
      }).all(new Predicate&lt;Integer&gt;() {
          @Override
          public boolean test(Integer integer) throws Exception {
              return integer &gt; 0;
          }
      }).filter(new Predicate&lt;Boolean&gt;() {
          @Override
          public boolean test(Boolean aBoolean) throws Exception {
              return aBoolean;
          }
      }).subscribe(new Observer&lt;Boolean&gt;() {
          @Override
          public void onSubscribe(Disposable d) {
  
          }
  
          @Override
          public void onNext(Boolean value) {
              Log.d("STATUS: ", "OK");
          }
  
          @Override
          public void onError(Throwable e) {
  
          }
  
          @Override
          public void onComplete() {
              Log.d("STATUS: ", "COMPLETE");
          }
      })
  </code></pre>
  
  <p>So, AndroidStudio marks me error on subscribe(new Observer).
  My objective is transform the names to a number by the length, so with all I hope make a condition, obviously it will be true, and late, filter that TRUE, from filter, and next show me a log message saying OK!</p>
  
  <p>I hope that you can help me!
  Thanks!</p>