= 0; i&lt;10; i++) {
    strBuilder.append(i);
  }
  str = strBuilder.toString();
</code></pre>
<!-- tooltip end -->
<p>
  Sometimes, the quick-fixes allow you to convert a <code>String</code> variable to a <code>StringBuilder</code> or
  introduce a new <code>StringBuilder</code>. Be careful if the original code specially handles the <code>null</code> value, as the
  replacement may change semantics. If <code>null</code> is possible, null-safe fixes that generate
  necessary null-checks are suggested. Also