Introduction

• Vector is a legacy class in Java that implements the List interface.
  • It is known as a legacy class because it was introduced in JDK 1.0 and later modified and integrated into the Java Collections Framework.
  • It is primarily retained for legacy code compatibility and is therefore used very infrequently in modern Java applications.
• It is present in the java.util package.
• It was introduced in JDK 1.0 as part of the original Collection classes.

• Hierarchy:
  • 

• Syntax :-

  package java.util;
  
  public class Vector<E> implements List<E>, RandomAccess, Cloneable, java.io.Serializable
  {
      // Constructors
      
      // Methods
      
      // Fields
  }

  • Vector implements the List interface, making it part of the Java Collection Framework (after JDK 1.2).
  • It implements RandomAccess, so elements can be accessed quickly by index (like ArrayList).

• Vector is a growable array that stores elements dynamically, similar to ArrayList.
  
  

Constructors of Vector Class

• Below are the constructors defined in the Vector class:

Methods of Vector Class

• Below are some methods defined specifically in the Vector class:

Program :

• In below program, we are directly using the Vector class.

• import java.util.Vector;
  
  public class VectorDemo
  {
      public static void main(String[] args)
      {
          Vector<String> vector = new Vector<>();
  
          // Adding elements
          vector.add("Apple");
          vector.add("Banana");
          vector.add("Mango");
          vector.add("Banana"); // duplicate allowed
  
          System.out.println(vector);
  
          System.out.println("-------------------------");
  
          // Accessing first and last elements
          System.out.println("First Element: " + vector.firstElement());
          System.out.println("Last Element: " + vector.lastElement());
  
          System.out.println("-------------------------");
  
          // Updating element
          vector.set(1, "Orange");
          System.out.println(vector);
  
          System.out.println("-------------------------");
  
          // Removing element
          vector.remove("Apple");
          System.out.println(vector);
  
          System.out.println("-------------------------");
  
          // Using Vector as a Stack
          vector.add(0, "Grapes"); // equivalent to push at beginning
          vector.add("Pineapple"); // add at end
          System.out.println(vector);
  
          System.out.println("-------------------------");
  
          // Iterating Vector
          for(String fruit : vector)
          {
              System.out.println(fruit);
          }
      }
  }

  Output:

  [Apple, Banana, Mango, Banana]
  -------------------------
  First Element: Apple
  Last Element: Banana
  -------------------------
  [Apple, Orange, Mango, Banana]
  -------------------------
  [Orange, Mango, Banana]
  -------------------------
  [Grapes, Orange, Mango, Banana, Pineapple]
  -------------------------
  Grapes
  Orange
  Mango
  Banana
  Pineapple

Properties of Vector Class:

1. Vector is an index-based data structure, which means the first element is inserted at index 0.
2. Vector can store different data types or heterogeneous elements if generics are not used.
3. We can store duplicate elements in the Vector.
4. We can store null values in the Vector.
5. Vector follows the insertion order, meaning elements are retrieved in the same sequence they were added.
6. Vector does not follow the sorting order; sorting must be done explicitly using Collections.sort() or list.sort().
7. Vector is synchronized, making it thread-safe for individual operations.
8. Vector guarantees for data consistency.