What is Array List?

Contents

• What is Array List?
• Structure of Array List
  • Advantage of Array List
  • Disadvantage of Array List
• Operations for Array List
  • Insertion
  • Deletion
  • Get Data
  • Implementation

What is Array List?

• Array List is a data structure that implements the list using an array.

• Sequential Structure

  • stores data in order.

  

Structure of Array List

• Data is stored within the node.
  • Multiple data can be stored.
• Every element has its own address.
  • So, the address of a particular element can be calculated.

Advantage of Array List

• It takes O(1) to find a data in a particular location.
  • It is fast to access certain data using indexes.
• Random access is possible, it’s easy to access nth element.
• Memory is allocated in contiguous memory location for its data.
  • It’s possible to avoid memory overflow or shortage of memory.
• It is simple to implement.

Disadvantage of Array List

• The size of the array is fixed.
  • When the array is full, it’s not possible to add new data.
  • Therefore, an array of larger sizes than the number of data to be stored must be created, which is a waste of memory space.
  • If the array is smaller than the number of data to be stored, it can cause problems.
• The time complexity of adding and deleting data is O(N).

Operations for Array List

Insertion

• If we simply add new data, add the data from the left side of the array sequentially.
• However, if new data is added where the data already exists, all existing data must be moved.
  • Move the data on the right first.

Deletion

• The data on the right can be easily removed.
• However, if we remove the data in the middle, we have to fill in the empty space.

Get Data

• We can easily find it by using the location of the data we want to find.

Implementation

GitHub