Get element index « Vector « List « Collections

Return	Method	Summary
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"));
  }
}

0
2


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);
  }
}


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