title: Cut off a specific part in a String
body: <p>For examples, I have:</p>
  
  <pre><code>String s = "{\"ABC\"}:Mycontent{\"123\"}";
  </code></pre>
  
  <p>I only want to get the Mycontent{"123"} part and this part can be changed dynamically. Can anybody please show me how to do it (Fast performance)?</p>