old for loop vs new for loop

[pras]

what is the main diffrence here?

can anyone explain with a simple example?


regards ,
prasanna.s.k

[Rob Spoor]

The main difference is easier readability, at the cost of losing the iterator or array index.

Observe:

int[] array;
for (int i: array)
{
    System.out.println(i);
}
Collection<String> collection;
for (String s: collection)
{
    System.out.println(s);
}

versus

int[] array;
for (int i = 0; i < array.length; i++)
{
    System.out.println(array[i]);
}
Collection<Stirng> collection;
for (Iterator<String> i = collection.iterator(); i.hasNext(); )
{
    String s = i.next();
    System.out.println(s);
}

So, when should you use the new loop? The answer: whenever you feel like it, and do not need the array index or iterator. I'm already using it in 95% of the cases.

[Bill Shirley]

It basically hides the iterator.

This example doesn't display the space saving it can sometimes buy you, but it will become apparent if you start using it.

  Collection<String> stringCollection; // initialize
  String cat = "";
  
  for (Iterator<String> i = stringCollection.iterator(); i.hasNext(); )
    cat.concat(i.next());

  for (String part : stringCollection)
    cat.concat(part);

[ November 20, 2007: Message edited by: Bill Shirley ]

[pras]

thanks to the wonderfull and rocking replies.


it really helped


cheers,
Prasanna.s.k

Wish i could give a party for that!!!

[Campbell Ritchie]

. . . but remember the for-each loop ("new for loop") is read-only. You can get data from the individual members of the array, but you can't write

s = "xyz";

CR

[pras]

how can you write using the old for loop style? can you give a simple example







cheers

[Campbell Ritchie]

You can usually find the answer to that sort of question in the Java Tutorial.