Java .previousIndex()

The .previousIndex() method returns the index of the previous element from a ListIterator object. If there is not a previous element, it returns -1.

Syntax

int value = myListIterator.previousIndex();

Where myListIterator is a ListIterator object.

Example

The following example uses a ListIterator to traverse an ArrayList and then traverse it back in the opposite direction, printing the indices of each item:

import java.util.*;

public class Example {
  public static void main(String args[]) {
    // Create a new ArrayList
    ArrayList l = new ArrayList();

    // Add some items to the ArrayList
    l.add("A");
    l.add("B");
    l.add("C");
    l.add("D");
    l.add("E");

    ListIterator i = l.listIterator();

    // Loop through ArrayList contents
    while(i.hasNext()) {
      int index = i.nextIndex();
      Object item = i.next();
      System.out.println(index + ": " + item);
    }

    // Loop back through ArrayList contents
    while(i.hasPrevious()) {
      int index = i.previousIndex();
      Object item = i.previous();
      System.out.println(index + ": " + item);
    }
  }
}

Copy to clipboard
Copy to clipboard

This example outputs the following:

0: A
1: B
2: C
3: D
4: E
4: E
3: D
2: C
1: B
0: A

Copy to clipboard
Copy to clipboard