title: Under what conditions does Java's Scanner.hasNextLine() block?
body: <p>The javadoc for <code>Scanner.hasNextLine()</code> states:</p>
  
  <blockquote>
    <p>Returns true if there is another line in the input of this scanner.
    This method <strong><em>may</em></strong> block while waiting for input. The scanner does
    not advance past any input.</p>
  </blockquote>
  
  <p>Under what conditions will the method block?</p>