Vector in Java

Vector is a legacy implementation of a list added to Java since version 1.0. It was later moved to the Java Collections Framework and retrofitted to implement the List interface.

Vectors are synchronized. All the methods in the Vector class are synchronized, ensuring that only one thread can access a method at a time.

Vector implements Iterator and ListIterator and Enumeration interface.

Creating and initializing Vector

//Using default constructor
Vector<String> vector1 = new Vector<>();
vector1.add("One");
vector1.add("Two");
vector1.add("Three");

// Initial capacity of 20
Vector<String> vector2 = new Vector<>(20);
vector2.add("One");
vector2.add("Two");
vector2.add("Three");

// Initial capacity of 20, capacity increment of 5
Vector<String> vector3 = new Vector<>(20, 5);
vector3.add("One");
vector3.add("Two");
vector3.add("Three");

//Creating vector from another collection
ArrayList<String> list = new ArrayList<>();
list.add("One");
list.add("Two");
list.add("Three");
Vector<String> vector4 = new Vector<>(list);

Iterate Items in Vector

Vectors can be iterated using for loop, enhanced for loop, Java 8 forEach, Iterator, ListIterator or using Enumeration.

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

// Enhanced for Loop
for (String element: vector) {
     System.out.println(element);
}

//using iterator
Iterator<String> iterator = vector.iterator();
while (iterator.hasNext()) {
    System.out.println(iterator.next());
}

// using a ListIterator
ListIterator<String> listIterator = vector.listIterator();
while (listIterator.hasNext()) {
    System.out.println(listIterator.next());
}

// Using Enumeration
Enumeration<String> enumeration = vector.elements();
while (enumeration.hasMoreElements()) {
    System.out.println(enumeration.nextElement());
}

//Using Java 8 forEach
vector.forEach(element -> {
    System.out.println(element);
});