Vector lastIndexOf() Method in Java

The Java.util.Vector.lastIndexOf(Object element) method is used to check and find the occurrence of a particular element in the vector. If the element is present in the vector then the lastIndexOf() method returns the index of last occurrence of the element otherwise it returns -1. This method is used to find the last occurrence of a particular element in a vector. 

Syntax:

Vector.lastIndexOf(Object element)

Parameters: The parameter element is of type Vector. It refers to the element whose last occurrence is required to be checked. 

Return Value: The method returns the position of the last occurrence of the element in the Vector. If the element is not present in the Vector then the method returns -1. The returned value is of integer type. 

Below programs illustrate the Java.util.Vector.lastIndexOf() method: 

Program 1:

Java

// Java code to illustrate lastIndexOf()
import java.util.*;

public class VectorDemo {
    public static void main(String args[])
    {

        // Creating an empty Vector
        Vector<String> vec_tor = new Vector<String>();

        // Use add() method to add elements in the Vector
        vec_tor.add("Geeks");
        vec_tor.add("for");
        vec_tor.add("Geeks");
        vec_tor.add("10");
        vec_tor.add("20");

        // Displaying the Vector
        System.out.println("Vector: " + vec_tor);

        // The last position of an element is returned
        System.out.println("Last occurrence of Geeks is at index: "
                           + vec_tor.lastIndexOf("Geeks"));
        System.out.println("Last occurrence of 10 is at index: "
                           + vec_tor.lastIndexOf("10"));
    }
}

Output:

Vector: [Geeks, for, Geeks, 10, 20]
Last occurrence of Geeks is at index: 2
Last occurrence of 10 is at index: 3

Program 2:

Java

// Java code to illustrate lastIndexOf()
import java.util.*;

public class VectorDemo {
    public static void main(String args[])
    {

        // Creating an empty Vector
        Vector<Integer> vec_tor = new Vector<Integer>();

        // Use add() method to add elements in the Vector
        vec_tor.add(10);
        vec_tor.add(22);
        vec_tor.add(3);
        vec_tor.add(10);
        vec_tor.add(20);

        // Displaying the Vector
        System.out.println("Vector: " + vec_tor);

        // The last position of an element is returned
        System.out.println("Last occurrence of 10 is at index: "
                           + vec_tor.lastIndexOf(10));
        System.out.println("Last occurrence of 20 is at index: "
                           + vec_tor.lastIndexOf(20));
    }
}

Output:

Vector: [10, 22, 3, 10, 20]
Last occurrence of 10 is at index: 3
Last occurrence of 20 is at index: 4

Time complexity: O(n). // n is the size of the vector.
Auxiliary Space: O(n).