How to sort an Array ArrayList?

Processing Beginners
5 


import java.util.Collections;  // Import the Collections class

ArrayList <ArrayList <Float> > list = new ArrayList();

// --------------------------------------------------------------------------------

ArrayList <Float> listA = new ArrayList();

listA.add (17.1); 
listA.add (7.7);
listA.add (12.9);

list.add(listA); 

listA=null; 

// -----------------------------------------------
// Use 

println(list.get(0));  

Collections.sort(list.get(0)); 

println(list.get(0));