Difference Between ArrayList and Vector in Java — Java Technical Interview Questions & Answers

Difference Between ArrayList and Vector in Java

Difference Between ArrayList and Vector in Java

  • ArrayList is a resizable array: fast get by index, slower insert in the middle. LinkedList is nodes with next/prev: faster insert/delete at ends, slower random index get.
  • Day to day, almost every fresher program uses ArrayList. Use LinkedList only when you truly insert/delete a lot at the ends.
  • Vector is like an old synchronized ArrayList. Prefer ArrayList + explicit sync if you need thread safety.
  • Let's take this on the board with one tiny Main class — no extra files. Difference Between ArrayList and Vector in Java — output: 2 then Asha. add Asha, add Ravi. size is 2. get(0) is Asha. get(2) would throw IndexOutOfBoundsException. Start from main, go line by line, and stop at each print. That output is the proof for Difference Between ArrayList and Vector.
  ArrayList names
    add("Asha")  add("Ravi")
         │
         ▼
    [0]=Asha  [1]=Ravi   size=2

Technical Interview Tip: Say: ArrayList = dynamic array with index access.

Code Examples for Difference Between ArrayList and Vector in Java

Example

import java.util.ArrayList;

// ArrayList demo
public class Main {
  public static void main(String[] args) {
    ArrayList<String> names = new ArrayList<>();
    names.add("Asha");
    names.add("Ravi");
    System.out.println(names.size());
    System.out.println(names.get(0));
  }
}

Difference Between ArrayList and Vector in Java — output: 2 then Asha. add Asha, add Ravi. size is 2. get(0) is Asha. get(2) would throw IndexOutOfBoundsException.

How to Explain Difference Between ArrayList and Vector in Java to an Interviewer

What is the difference in Difference Between ArrayList and Vector?

ArrayList = resizable array. LinkedList = node chain. ArrayList fast get(i). LinkedList fast insert/delete at ends. Default pick ArrayList. LinkedList only for end-heavy edits.

When do you pick each side?

Match the problem Don’t pick only what you revised last

Give one example of Difference Between ArrayList and Vector.

Show both sides Say the output

What mistake do beginners make?

Mixing both ideas Only memorising names

Where is Difference Between ArrayList and Vector used?

Real Java program