In Python, the enumerate
function allows you to iterate over a sequence of (index, value) pairs. For example:
>>> numbers = ["zero", "one", "two"] >>> for i, s in enumerate(numbers): ... print i, s ... 0 zero 1 one 2 two
Is there any way of doing this in Java?
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Answer
For collections that implement the List
interface, you can call the listIterator()
method to get a ListIterator
. The iterator has (amongst others) two methods – nextIndex()
, to get the index; and next()
, to get the value (like other iterators).
So a Java equivalent of the Python above might be:
import java.util.ListIterator; import java.util.List; List<String> numbers = Arrays.asList("zero", "one", "two"); ListIterator<String> it = numbers.listIterator(); while (it.hasNext()) { System.out.println(it.nextIndex() + " " + it.next()); }
which, like the Python, outputs:
0 zero 1 one 2 two