how to print the index number of elements in the ArrayList using for each looping

Question

Can anybody tell me how to print the index number of elements in the ArrayList using for each looping in Java.

Answer 1

like @Michael's but shorter. A pet obsession I'll admit.

List<String> list = Arrays.asList("zero", "one", "two", "three");
int index=0;
for(String s : list)
    System.out.println((index++)+": "+s);

prints

0: zero
1: one
2: two
3: three

Answer 2

You have to keep track of the index numbers yourself, as you loop through the ArrayList. The List iterator won't do that for you.

You'd normally do that through a separate variable. You could store objects with an associated index, but you'd have to be sure to maintain ordering (by not deleting, resorting etc.)

Answer 3

By keeping a separate index count:

int index=0;
for(String s : list){
    System.out.println(String.valueOf(index++)+": "+s);
}

Probably makes more sense to use a regular for loop instead. The "enhanced for loop" is based on the Iterable and Iterator interfaces - it doesn't know anything about implementation details of the underlying collection (which may well not have an index for each element).

Answer 4

You'll need to either iterate with an integer index, or keep a counter going.

List<kind> aList;
...
int index = 0;
for(kind x  :  aList)
{
   ...
   index++;
}

or

for(int index = 0; index < aList.size(); index++)
{
    Kind x = aList.get(index)
...
}