title: How do the StringBuffer insert() and deleteCharAt() methods work
body: <p>In Java there is methods in either <code>StringBuffer()</code> or <code>StringBuilder()</code> called <code>insert()</code> and <code>deleteCharAt()</code> I am very interested in understanding a little more how these two specific methods work. Or how one would program one using the standard java String methods. I reckon they are pretty simple methods to write yourself?  </p>