title: Split a string on whitespace, numbers, and operators with regex
body: <p>I was wondering if it was possible to split a string on whitespace, and avoid all numbers, whitespace and operators such as + and -</p>
  
  <p>This is what I have, but I believe it is incorrect</p>
  
  <pre><code>  String [] temp = expression.split("[ \\+ -][0-9] ");
  </code></pre>
  
  <p>Suppose I have an expression </p>
  
  <pre><code>x+y+3+5+z
  </code></pre>
  
  <p>I want to get rid of everything else and only put x, y, and z into the array</p>