What is the use of this New Enhanced for loop feature ??

[Ravi Kiran Va]

Hi all ,

I am trying to uunderstand the New For loop Enhanced Feature .

I have written this sample Example for my understanding purpose .

List<String> list = new ArrayList<String>();
		list.add("One");
		list.add("Two");
		list.add("Three");
		list.add("Four");

		for (String names : list) {
			System.out.println(names);
		}

		System.out.println("\n");

		for (int i = 0; i < list.size(); i++) 
		{
		System.out.println(list.get(i));
		}

This works fine .
Could anybody tell me , with this new Enhanced feature will the performance would be increased ??
Or What is the use of this New Enhanced for loop feature ?? Please guide me , Thanks .

[Jaikiran Pai]

http://download.oracle.com/javase/1.5.0/docs/guide/language/foreach.html

[Rob Spoor]

Ravi Kiran Va wrote:This works fine .

Try again with a LinkedList with several thousands of objects. See how well it performs.

Here's a little test program for you:

import java.util.*;

public class Test
{
    public static void main(String[] args) throws Exception
    {
        final int count = 100000;
        List<Integer> al = new ArrayList<Integer>(count);
        List<Integer> ll = new LinkedList<Integer>();

        for (int i = 0; i < count; i++)
        {
            al.add(i);
            ll.add(i);
        }

        test(al);
        test(ll);
    }

    private static void test(List<Integer> list)
    {
        System.out.println(list.getClass().getName());
        int count = 0;
        long start = System.currentTimeMillis();
        for (int i = 0; i < list.size(); i++)
        {
            list.get(i);
            count++;
        }
        long end = System.currentTimeMillis();
        System.out.println("get: " + (end - start));

        start = System.currentTimeMillis();
        for (int i: list)
        {
            count++;
        }
        end = System.currentTimeMillis();
        System.out.println("for-each: " + (end - start));
    }
}

[Jesper de Jong]

The main advantage is that it makes your source code simpler and easier to read. Using the new enhanced for loop does not automatically increase performance.

By the way, it isn't really that new anymore, it was introduced in Java 5 which was released in September 2004, more than six years ago...

[Ravi Kiran Va]

Thank you very much Rob Prime and Jesper de Jong , as usual you rock .
Anyways ,I know that , Posting a question in this Category (Java in General or Java Beginer ) will yield me prompt results