title: Java RegEx lookbehind construction
body: <p>Need a little help to construct a regular expression for this scenario:</p>
  
  <p>Contents:</p>
  
  <pre><code>&lt;b&gt;IfThisIsPresent:&lt;/b&gt;
  &lt;span style="font-family:Arial"&gt;
  &lt;button type='submit'&gt;
  &lt;span class="button-gradient"&gt;
  &lt;span class="button-test"&gt;
  Look: NeedToExtractThat
  &lt;/span&gt;
  </code></pre>
  
  <p>So:
  if string <code>IfThisIsPresent:</code> is in my string, I should extract what is right after <code>Look:</code> string.</p>
  
  <p>I developed the following RegEx, but it's not working:</p>
  
  <pre><code>((?&lt;=IfThisIsPresent:)Look:(.*))
  </code></pre>
  
  <p>I know Java Pattern class doesn't support if then else. So I'm using lookbehind to check if <code>IfThisIsPresent</code> exists, then extract what is after <code>Look:</code>.</p>
  
  <p>Could someone help?</p>
  
  <p>Appreciated!</p>