Java Vector

What exactly is a Java Vector?

Think of it as a dynamic array that automatically grows and shrinks as you add or remove elements. It's like having a magical backpack that expands to fit all your treasures and contracts when you need a little less.

Creating a Vector

Creating a Vector is as easy as. You simply declare it and start adding elements:

import java.util.Vector;

public class VectorExample {
    public static void main(String[] args) {
        Vector<String> myVector = new Vector<>();
        myVector.add("Apple");
        myVector.add("Banana");
        myVector.add("Orange");

        System.out.println("My vector: " + myVector);
    }
}

Dynamic Resizing

One of the coolest things about Java Vector is its ability to resize dynamically. So, even if you start with a small size, it can grow to accommodate more elements without breaking a sweat:

import java.util.Vector;

public class VectorExample {
    public static void main(String[] args) {
        Vector<Integer> myVector = new Vector<>(3); // Start with initial capacity of 3
        myVector.add(1);
        myVector.add(2);
        myVector.add(3);
        myVector.add(4); // No problem, Vector grows automatically

        System.out.println("My vector: " + myVector);
    }
}

Synchronization

Another cool feature of Java Vector is its built-in synchronization. This means it's safe to use in multithreaded environments without worrying about data corruption:

import java.util.Vector;

public class VectorExample {
    public static void main(String[] args) {
        Vector<Integer> myVector = new Vector<>();
        myVector.add(1);
        myVector.add(2);
        myVector.add(3);

        // Thread 1
        new Thread(() -> {
            synchronized (myVector) {
                System.out.println("Thread 1: " + myVector);
            }
        }).start();

        // Thread 2
        new Thread(() -> {
            synchronized (myVector) {
                System.out.println("Thread 2: " + myVector);
            }
        }).start();
    }
}

Iterating Over Elements

Iterating over the elements of a Vector is a piece of cake. You can use a simple for loop or enhanced for loop:

import java.util.Vector;

public class VectorExample {
    public static void main(String[] args) {
        Vector<String> myVector = new Vector<>();
        myVector.add("Apple");
        myVector.add("Banana");
        myVector.add("Orange");

        // Using for loop
        System.out.println("Using for loop:");
        for (int i = 0; i < myVector.size(); i++) {
            System.out.println(myVector.get(i));
        }

        // Using enhanced for loop
        System.out.println("Using enhanced for loop:");
        for (String fruit : myVector) {
            System.out.println(fruit);
        }
    }
}

Methods in Vector

Method	Description
void addElement(Object obj)	Adds the specified component to the end of this vector, increasing its size by one.
boolean removeElement(Object obj)	Removes the first occurrence of the specified element in this vector, if it is present.
Object remove(int index)	Removes the element at the specified position in this vector.
void removeAllElements()	Removes all components from this vector and sets its size to zero.
void clear()	Removes all of the elements from this vector.
Object elementAt(int index)	Returns the component at the specified index.
void setElementAt(Object obj, int index)	Sets the component at the specified index of this vector to be the specified object.
int size()	Returns the number of components in this vector.
boolean isEmpty()	Tests if this vector has no components.
void ensureCapacity(int minCapacity)	Increases the capacity of this vector, if necessary, to ensure that it can hold at least the number of components specified by the minimum capacity argument.
int capacity()	Returns the current capacity of this vector.
void trimToSize()	Trims the capacity of this vector to be the vector's current size.
void setSize(int newSize)	Sets the size of this vector.
Enumeration<E> elements()	Returns an enumeration of the components of this vector.
boolean contains(Object o)	Returns true if this vector contains the specified element.
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 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.
Object clone()	Returns a shallow copy of this vector.
void copyInto(Object[] anArray)	Copies the components of this vector into the specified array.
String toString()	Returns a string representation of this vector.
void setSize(int newSize)	Sets the size of this vector.
void add(int index, E element)	Inserts the specified element at the specified position in this vector.
E remove(int index)	Removes the element at the specified position in this vector and returns the removed element.
void clear()	Removes all of the elements from this vector.