title: How to 'pre increment' a BigInteger in Java?
body: <p>I have a <code>for</code> loop with <code>BigInteger</code>s, something like this:</p>
  
  <pre><code>for(BigInteger a = BigInteger.valueOf(1); a.compareTo(someBigInteger); ++a) {...
  </code></pre>
  
  <p>Obviously I can't use the <code>++</code> operator on a non-primitive. How do I work around this?</p>
  
  <p>Also, I have to use <code>BigInteger</code> in this scenario.</p>