Netbeans - Method Cannot Be Applied To Given Types

Here is my code:

import java.util.*;public class DebugSix {
public static void main(String[] args) {

ArrayList<String>products = new ArrayList();
products.add("shampoo");
products.add("moisturizer");
products.add("conditioner");
Collections.sort(products);

[Code] ....

I am using netbeans and getting errors for display(); and size(); it is telling me the errors are :

for the display error, "method display in class DebugSix cannot be applied to given types;
display();" and for the size() is : "cannot find symbol System.out.println("
The size of the list is " + size());"