title: Java Stream API filter
body: <p>I have code:</p>
  
  <pre><code>static void doSmth() {
      ArrayList&lt;String&gt; list = new ArrayList&lt;&gt;();
      for (int i = 0; i &lt; 30; i++) {
          list.add(String.valueOf(i));
      }
      list.stream().filter("1329"::contains).map(s -&gt; s + "a").forEach(System.out::println);
  }
  </code></pre>
  
  <p>Why i got:</p>
  
  <pre><code> 1a
   2a
   3a
   9a
   13a
   29a
  </code></pre>
  
  <p>I expected a empty output, because list doesn't contains "1329".</p>