Java Vector

August 4, 2023

Java Vector is a dynamic data structure that can resize itself automatically like an array making efficient in managing collections of objects

It is similar to an ArrayList but is synchronized, which means that it is thread-safe and can be used in multi-threaded environments.

Java Vector also have some additional methods for inserting and removing elements at specific positions, as well as checking if an element is present in the Vector.

What is Java Vector Class?

The Java Vector class is a legacy data structure in Java that provides a dynamic array-like implementation of the List interface. It was introduced in Java 1.0 and is thread-safe, meaning that it can be safely accessed by multiple threads without explicit synchronization.

The Vector class implements several interfaces, including List, Collection, Iterable, and Enumeration. Some of its commonly used methods include add, remove, get, set, indexOf, lastIndexOf, and size.

2d Vector in Java In Java, a 2D vector (also called a 2D array or matrix) is a collection of elements arranged in a grid of rows and columns. Each element in the grid is identified by its row and column indices.

Java Vector Initialization:

In Java, you can initialize a Vector object using several different approaches, including:

Default Constructor: You can create an empty Vector object using the default constructor, as follows:

Vector<Object> vector = new Vector<>();

Constructor with Initial Capacity: You can create a Vector object with a specific initial capacity using the following constructor : where initialCapacity is an integer value that represents the initial size of the Vector.

Vector <object>vector = new Vector<>(initialCapacity);

Constructor with Capacity Increment: You can also create a Vector object with a specific capacity increment using the following constructor:
where initialCapacity is an integer value that represents the initial size of the Vector.
CapacityIncrement is an integer value that specifies the amount by which the Vector’s capacity should be increased when it needs to grow beyond its current capacity.

Vector <object> vector = new Vector<>(initialCapacity, capacityIncrement);

Initialization with Elements: You can also create a Vector object and initialize it with a collection of elements using the following constructor:

Vector <Object> vector = new Vector<>(initialCapacity);

where element1, element2, …, elementN are the elements that you want to add to the Vector.

Note that in each case, you can replace the Object type parameter with the type of the objects that you want to store in the Vector.

Java Vector vs ArrayList

Thread-safety:

Vector is thread-safe and synchronized while ArrayList is not.

Vector uses synchronization which makes it slower compared to ArrayList.

Capacity:

Vector can dynamically grow or shrink its capacity while ArrayList increases its capacity by half of its original size when it is full.

Vector can also specify an initial capacity while ArrayList cannot.

Performance:

ArrayList performs better than Vector in single-threaded applications because it is not synchronized.

In multi-threaded applications, Vector is preferred because it is thread-safe and synchronized.

Iterator:

Vector uses an enumeration interface for iteration while ArrayList uses the Iterator interface.

The Iterator interface is more efficient compared to the Enumeration interface.

Vector Methods In Java

Methods	Description
add(element):	Adds an element to the end of the Vector.
add(index, element):	Inserts an element at the specified index in the Vector.
addAll(collection):	Adds all elements of a collection to the end of the Vector.
get(index):	Returns the element at the specified index in the Vector.
set(index, element):	Replaces the element at the specified index in the Vector with the specified element.
remove(element):	Removes the first occurrence of the specified element from the Vector.
size():	Returns the number of elements in the Vector.
remove(index):	Removes the element at the specified index in the Vector.

The Java Vector class also provides several other methods for manipulating and accessing the elements of the Vector.

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Let’s look at the Java Vector to perform certain operations.

Example 1: Java Program to Show Java vector

Run

import java.util.Vector;

 
public class Main
{
  
public static void main (String[]args)
  {
    
      // Create a new Vector of integers
      Vector < Integer > numbers = new Vector < Integer > ();
    
 
      // Add some elements to the Vector
      numbers.add (1);
    
numbers.add (2);
    
numbers.add (3);
    
 
      // Print the contents of the Vector
      System.out.println ("Vector: " + numbers);
    
 
      // Remove an element from the Vector
      numbers.remove (1);
    
 
      // Print the contents of the Vector again
      System.out.println ("Vector after removing element: " + numbers);
    
 
      // Check if an element is present in the Vector
      if (numbers.contains (3))
      {
	
System.out.println ("Vector contains the element 3");
      
}
    else
      {
	
System.out.println ("Vector does not contain the element 3");
      
}
  
}

}

Output

Vector: [1, 2, 3]
Vector after removing element: [1, 3]
Vector contains the element 3

Explanation:

You can use the generic type Vector to create a Vector that can only hold integers. We have also used some of the methods provided by the Vector class, such as add, remove, and contains, to manipulate the contents of the Vector.

Example 2: Java Program to Create a Vector

Run

import java.util.Vector;

 
public class Main
{
  
public static void main (String[]args)
  {
    
      // Create an empty Vector of Strings
      Vector < String > vector = new Vector < String > ();
    
 
      // Add some elements to the Vector
      vector.add ("IPL");
    
vector.add ("PPL");
    
vector.add ("CPL");
    
 
      // Print the contents of the Vector
      System.out.println ("Vector: " + vector);
    
 
      // Create a Vector with initial capacity of 5
      Vector < Integer > numbers = new Vector < Integer > (5);
    
 
      // Add some elements to the Vector
      numbers.add (1);
    
numbers.add (2);
    
numbers.add (3);
    
 
      // Print the contents of the Vector
      System.out.println ("Numbers Vector: " + numbers);

} 
}

Output

Vector: [IPL, PPL, CPL]
Numbers Vector: [1, 2, 3]

Explanation:

This program creates two Vectors - one empty Vector of Strings and another Vector of Integers with an initial capacity of 5.

The program then adds some elements to each of these Vectors and prints their contents using the System.out.println method.

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Java Vector

What is Java Vector Class?

Java Vector vs ArrayList

Vector Methods In Java

Example 1: Java Program to Show Java vector

Output

Example 2: Java Program to Create a Vector

Output

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