Java Programs›Collections›Vector Example

Vector Example in Java

beginner· Collections · List

Problem

Vector is one of Java's original collection classes — a resizable, synchronized list that predates the modern Collections framework but still implements the same List interface ArrayList does.

Add elements to a Vector and read them back by index.

Input

add(Mercury), add(Venus), add(Earth)

Output

First: Mercury, Total: 3

Java Program

Java

import java.util.Vector;

public class VectorExample {
    public static void main(String[] args) {
        Vector<String> planets = new Vector<>();
        planets.add("Mercury");
        planets.add("Venus");
        planets.add("Earth");

        System.out.println("First: " + planets.get(0) + ", Total: " + planets.size());
    }
}

▶ Run Code

Output

First: Mercury, Total: 3

Core Logic

Vector behaves like an ArrayList for everyday add/get calls, since both implement the same List interface — the real difference between them is under the hood, not in how they're used.

How It Works

1new Vector<String>() creates a resizable list, added to with add() exactly like an ArrayList would be.
2planets.get(0) reads the element at index 0, the same indexed-access method ArrayList also provides.
3planets.size() reports how many elements the vector currently holds.
4Every method call here would look identical if Vector were swapped for ArrayList — the API surface for basic list operations is the same.

After adding Mercury, Venus, and Earth, get(0) returns "Mercury" and size() returns 3.

💡

Key Point: Vector's methods are internally synchronized, making it thread-safe for concurrent access — but that safety comes with locking overhead on every call, which is why ArrayList (unsynchronized) is preferred for ordinary single-threaded use, with Collections.synchronizedList() or a concurrent collection reached for instead when thread safety is genuinely needed today.

Complexity

Time Complexity: O(1)Space Complexity: O(1)

Why: add() and get() cost the same as they would on an ArrayList — amortized constant time each — the synchronization Vector adds affects concurrent throughput, not this asymptotic complexity.

Key Concepts

Vectorsynchronized collectionList interface

← Previous

TreeSet Example

Word Frequency with HashMap

Related Programs

Collectionsbeginner

ArrayDeque Example

Collectionsbeginner

ArrayList Basic Operations

Collectionsbeginner

ArrayList Basics

Collectionsbeginner

ArrayList Convert to Array

Collectionsbeginner

ArrayList Iteration