title: Should I avoid using "!" in if statement in Java?
body: <p>Our team's Java Coding Guideline says:</p>
  
  <blockquote>
    <p>Avoid using "!" in if statement as much as possible.</p>
  </blockquote>
  
  <p>I have asked other colleagues, but no one gave me clear ideas why, because the guideline was created a long time ago and the author might have left our company.</p>
  
  <p>Do you have any idea?</p>