This method returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
Syntax:
public int indexOf(Object o)
Parameters: This function has a single parameter, i.e, the element to be searched in the list.
Returns: This method returns the index of first occurrence of the given element in the list and returns “-1” if element is not in the list.
Below programs show the implementation of this method.
Program 1:
// Java code to show the implementation of// indexOf method in list interfaceimport java.util.*;public class GfG { // Driver code public static void main(String[] args) { // Initializing a list of type Linkedlist List<Integer> l = new LinkedList<>(); l.add(1); l.add(3); l.add(5); l.add(7); System.out.println(l); System.out.println(l.indexOf(5)); }} |
Output:
[1, 3, 5, 7] 2
Program 2: Below is the code to show implementation of list.hashCode() using Linkedlist.
// Java code to show the implementation of// indexOf method in list interfaceimport java.util.*;public class GfG { // Driver code public static void main(String[] args) { // Initializing a list of type Linkedlist List<String> l = new LinkedList<>(); l.add("10"); l.add("15"); l.add("20"); System.out.println(l); System.out.println(l.indexOf("20")); }} |
Output:
[10, 15, 20] 2
Reference:
Oracle Docs
