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Sorting an ArrayList

flesh-bound-book flesh-bound-book is offline
Junior Member
Join Date: Feb 2010
Posts: 1
Hey, guys. I have a homework assignment due later tonight and am having a bit of trouble. I have to sort an array list as part of the assignment. My understanding is that must use Collections.sort, but I can't get that to work. I am not sure if that is due to my use of generics or what. Here is my current code.

import java.util.ArrayList;
import java.util.Collections;

//create generic MyList class with type parameter T
final class MyList<T extends Number>{

    //create ArrayList of type T
    ArrayList<T> list = new ArrayList<T>();

    //create an add method that adds argument of type T to ArrayList
    public void add( T new_element ){
	list.add( new_element );

    //create method 'largest' that returns largest value of 'list'
    public T largest(){
	Collections.sort( list );
        //must return largest value after sorting

    //create method 'smallest' that returns smallest value of 'list'
    public T smallest(){
	Collections.sort( list );
	//must return smallest value after sorting

public final class GenericsHW{

    public static void main(final String[] args) {
	MyList<Number> list = new MyList<Number>();

	list.add( new Integer( 10  ) );
	list.add( new Double( 1.2 ) );

and the error messages I am getting are:

/MyDev/java/HW3/ cannot find symbol
symbol  : method sort(java.util.ArrayList<T>)
location: class java.util.Collections
	Collections.sort( list );
MyDev/java/HW3/ cannot find symbol
symbol  : method sort(java.util.ArrayList<T>)
location: class java.util.Collections
	Collections.sort( list );
I've looked at quite a few explanations of sorting arraylists, and they all achieve sorting with Collections.sort( ArrayList );, but this isn't working for me. They all used string values for sorting and I am using numbers, but it seems like Collections.sort would be able to sort values of the Number type. Any help would be great. Let me know if I left out something you need to know.

Last edited by flesh-bound-book; 02-13-2010 at 02:03 AM.. Reason: solved
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