title: BigInteger negative value
body: <p>I have a biginteger number, say</p>
  
  <pre><code>BigInteger a=Biginteger.valueOf(50);
  </code></pre>
  
  <p>Besides the following</p>
  
  <pre><code>BigInteger a=(BigInteger.ZERO).subtract(BigInteger.valueOf(50));
  </code></pre>
  
  <p>is there another way to get the negative value of my number? Can't seem to find a method.</p>