Get element index

int indexOf(Object o): Returns the index of the first occurrence of the specified element in this vector, or -1 if this vector does not contain the element.
int indexOf(Object o, int index): Returns the index of the first occurrence of the specified element in this vector, searching forwards from index, or returns -1 if the element is not found.
int lastIndexOf(Object o): Returns the index of the last occurrence of the specified element in this vector, or -1 if this vector does not contain the element.
int lastIndexOf(Object o, int index): Returns the index of the last occurrence of the specified element in this vector, searching backwards from index, or returns -1 if the element is not found.


import java.util.Vector;

public class Main{

  public static void main(String args[]) {

    Vector v = new Vector();

    v.add("java2s.com");
    v.add("java2s.com");
    v.add("java2s.com");
    
    System.out.println(v.indexOf("java2s.com"));
    System.out.println(v.lastIndexOf("java2s.com"));
  }
}

The output:

0
2

Search an element of Vector from specific index


import java.util.Vector;

public class Main {
  public static void main(String[] args) {
    Vector v = new Vector();
    v.add("1");
    v.add("2");
    v.add("3");
    v.add("4");
    v.add("java2s.com");
    v.add("1");
    v.add("2");
    int index = v.indexOf("1", 4);
    if (index == -1)
      System.out.println("Vector does not contain 1 after index # 4");
    else
      System.out.println("Vector contains 1 after index # 4 at index #" + index);

    int lastIndex = v.lastIndexOf("2", 5);
    
    if (lastIndex == -1)
      System.out.println("not contain 2 after index # 5");
    else
      System.out.println("Last occurrence of 2 after index 5 #" + lastIndex);
  }
}

The output:


Vector contains 1 after index # 4 at index #5
Last occurrence of 2 after index 5 #1