title: java: use StringBuilder to insert at the beginning
body: <p>I could only do this with String, for example: </p>
  
  <pre><code>String str="";
  for(int i=0;i&lt;100;i++){
      str=i+str;
  }
  </code></pre>
  
  <p>Is there a way to achieve this with StringBuilder? Thanks.</p>