Search elements in Vector using index – Java example

In this tutorial, we will learn four following ways to search elements in Vector using index value.

1) public int indexOf(Object o): It returns the index of first occurrence of Object o in Vector.
2) public int indexOf(Object o, int startIndex): It returns the index of the first occurrence of the Object o in this vector, searching forwards from startIndex (inclusive).
3) public int lastIndexOf(Object o): It returns the index of last occurrence of Object o in Vector.
4) public int lastIndexOf(Object o, int startIndex): It returns the index of the last occurrence of the specified element in this vector, searching backwards from startIndex(inclusive).

Example

In this example, we have used all the above mentioned four methods to demonstrate their working.

import java.util.Vector;
public class SearchVector {
  public static void main(String[] args) { 
     // Create a Vector object
     Vector<String> vector = new Vector<String>();
 
     //Add elements to Vector
     vector.add("Kate");
     vector.add("Patt");
     vector.add("Kluge");
     vector.add("Karon");
     vector.add("Patt");
     vector.add("Monica");
     vector.add("Patt");
 
     //This would return the index of first occurrence
     int first_index = vector.indexOf("Patt");
     System.out.println("First Occurrence of Patt at index: "+first_index);
 
     //This would return the index of last occurrence
     int last_index = vector.lastIndexOf("Patt");
     System.out.println("Last Occurrence of Patt at index: "+last_index);
 
     //This would start search from index 2(inclusive)
     int after_index = vector.indexOf("Patt", 2);
     System.out.println("Occurrence after index 2: "+after_index);
 
     //This would search the element backward starting from index 6(inclusive)
     int before_index = vector.lastIndexOf("Patt", 6);
     System.out.println("Occurrence before index 6: "+before_index);
  } 
}

Output:

First Occurrence of Patt at index: 1
Last Occurrence of Patt at index: 6
Occurrence after index 2: 4
Occurrence before index 6: 6

Reference
Vector javadoc