title: Java 7 underscore in numeric literals
body: <p>When we must use a <code>_</code> to separate digits in a number I don't understand the following case in which I can't use it:</p>
  
  <blockquote>
    <p>In positions where a string of digits is expected</p>
  </blockquote>
  
  <p>(as documented in the JDK7 guide <a href="https://docs.oracle.com/javase/7/docs/technotes/guides/language/underscores-literals.html" rel="noreferrer">here</a>)</p>
  
  <p>Some examples?</p>