title: Sorting a part of Java ArrayList
body: <p>What is the <strong>most efficient</strong> way of sorting only a part of ArrayList? 
  Say all elements from index 0 to 3 in an Arraylist which contains 10 elements.</p>
  
  <p>Is there a library function available in Java?</p>
  
  <p>Apart from <code>Collections.sort(list)</code> which sorts the entire List!</p>
  
  <p>Writing a highly optimised custom sort function will take some work. </p>