Searching Elements in Vector Using Index in Java
Last Updated :
22 Dec, 2020
Vector implements a dynamic array that means it can grow or shrink as required. Like an array, it contains components that can be accessed using an integer index. An element of a Vector can be searched using an index with different methods. Suppose if the element is not present in the Vector then the method will return -1.
Method 1: (Using indexOf(Object o))
Declaration
public int indexOf(Object o)
Syntax:
Vector.indexOf(Object element)
Parameters: This method accepts a mandatory parameter element of the type of Vector. It specifies the element whose occurrence is needed to be checked in the Vector
Return Value: This method returns the index or position of the first occurrence of the element in the vector. Else it returns -1 if the element is not present in the vector. The returned value is of integer type.
Java
// Searching Elements in Vector Using Index in Java
import java.util.Vector;
public class GFG {
public static void main(String args[])
{
// initialization Of Vector
Vector<String> details = new Vector<>(10);
// Adding Elements To The
// Vector
details.add("Geeks For Geeks");
details.add("Welcome");
details.add("Bob");
details.add("Hello");
details.add("Geeks For Geeks");
// Searching The Index Of Element
System.out.println(
"The index of element Geeks For Geeks in Vector is: "
+ details.indexOf("Geeks For Geeks"));
System.out.println(
"The index of element 2100 in Vector is: "
+ details.indexOf(2100));
}
}
OutputThe index of element Geeks For Geeks in Vector is: 0
The index of element 2100 in Vector is: -1
Method 2: (Using lastIndexOf(Object o))
Declaration
public int lastIndexOf(Object o)
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.
Java
// Searching Elements in Vector
// Using Index in Java
import java.util.Vector;
public class GFG {
public static void main(String args[])
{
// initialization Of Vector
Vector<String> details = new Vector<>(10);
// Adding Elements To The
// Vector
details.add("Geeks For Geeks");
details.add("Welcome");
details.add("Bob");
details.add("Hello");
details.add("Geeks For Geeks");
// print an element using it's index
System.out.println(
"The index of element Geeks For Geeks in Vector is: "
+ details.lastIndexOf("Geeks For Geeks"));
}
}
OutputThe index of element Geeks For Geeks in Vector is: 4
Method 3: (Using indexOf(Object, int) method)
Declaration
public int indexOf(Object o, int Starting_Index)
Syntax
Vector.indexOf(Object, int)
Parameters:
- starting_index: It is an index where to start searching for an element in the forward direction.
- o: It is an element to search for.
Return Value: The Index Of the first occurrence Of the Object(o) In this Vector, searching from the given starting_Index
Java
// Searching Elements in Vector Using Index in Java
import java.util.Vector;
public class GFG {
public static void main(String args[])
{
// initialization Of Vector
Vector<String> details = new Vector<>(10);
// Adding Elements To The
// Vector
details.add("Geeks For Geeks");
details.add("Welcome");
details.add("Bob");
details.add("Hello");
details.add("Bob");
details.add("Geeks For Geeks");
System.out.println(
"The index of element Bob in Vector is: "
+ details.indexOf("Bob", 3));
}
}
OutputThe index of element Bob in Vector is: 4
Method 4: (Using lastIndexOf(Object, int) method)
Declaration
public int lastIndexOf(Object o, int Starting_Index)
Syntax
Vector.lastIndexOf(Object, int)
Parameters:
- starting_index: It is an index where to start searching for an element in the backward direction.
- o: It is an element to search for.
Return Value: The Index of the last occurrence of the specified element In this Vector, searching backward from Starting_Index.
Java
// Searching Elements in Vector Using Index in Java
import java.util.Vector;
public class GFG {
public static void main(String args[])
{
// create a instance of vector
Vector<String> details = new Vector<>(10);
// Adding Elements To The
// Vector
details.add("Geeks For Geeks");
details.add("Welcome");
details.add("Bob");
details.add("Hello");
details.add("Bob");
details.add("Geeks For Geeks");
System.out.println(
"The index of element Bob in Vector is: "
+ details.lastIndexOf("Bob", 4));
}
}
OutputThe index of element Bob in Vector is: 4