title: Check whether a string is not null and not empty
body: <p>How can I check whether a string is not null and not empty?</p>
  
  <pre><code>public void doStuff(String str)
  {
      if (str != null &amp;&amp; str != "**here I want to check the 'str' is empty or not**")
      {
          /* handle empty string */
      }
      /* ... */
  }
  </code></pre>