title: extract substring in java using regex
body: <p>I need to extract <code>"URPlus1_S2_3"</code> from the string: </p>
  
  <pre><code>"Last one: http://abc.imp/Basic2#URPlus1_S2_3," 
  </code></pre>
  
  <p>using regular expression in Java language. </p>
  
  <p>Can someone please help me? I am using regex for the first time.</p>