The previous index and next index in an ArrayList can be obtained using the methods previousIndex() and nextIndex() respectively of the ListIterator interface. previousIndex() can also return -1 if it at the beginning of the list.
Input: list = [2, 3, 6, 8] listiterator is at the beginning find previous index. Output: -1 Input: list = [2, 3, 6, 8] listiterator is at the beginning find next index.
Steps to use previousIndex() and nextIndex():
- Create an empty ArrayList
- Add elements to ArrayList.
- Create a listiterator using listIterator() method.
Listiterator<Integer>iterator = arrList.listIterator();
- Now get the required index using the below commands
Returns: the index of the element that would be returned by a subsequent call to previous, or -1 if the list iterator is at the beginning of the list
Returns: the index of the element that would be returned by a subsequent call to next, or list size if the list iterator is at the end of the list
Initial arraylist =>[5, 10, 15, 20, 25, 30] previous index =>-1 Next index =>2
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