What is the difference between array and array list?

Asked 06-Dec-2019
Updated 30-Jun-2023
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Arrays and ArrayLists

Arrays and ArrayLists are both data structures that can be used to store a collection of elements. However, there are some key differences between the two.

  • Size: Arrays are fixed-size data structures, while ArrayLists are variable-size data structures. This means that you must specify the size of an array when you create it, while you can add or remove elements from an ArrayList as needed.
  • Elements: Arrays can store any type of data, including primitives and objects. ArrayLists can only store objects.
What is the difference between array and array list
  • Methods: Arrays have a limited set of methods for accessing and manipulating their elements. ArrayLists have a more extensive set of methods, including methods for adding, removing, searching, and sorting elements.
  • Performance: Arrays are generally faster than ArrayLists for accessing elements. This is because arrays can access their elements directly, while ArrayLists must first iterate through the list to find the desired element.
  • Memory usage: Arrays typically use less memory than ArrayLists. This is because arrays do not need to store any additional information about the size of the list.

In general, arrays are a good choice when you know the size of the data structure in advance and you need fast access to the elements. ArrayLists are a good choice when you need a variable-size data structure or you need to be able to add or remove elements frequently.

Which one should you use?

The best choice for you will depend on your specific needs. If you need a fixed-size data structure with fast access to the elements, then an array is a good choice. If you need a variable-size data structure or you need to be able to add or remove elements frequently, then an ArrayList is a better choice.

Here are some examples of when you might use each:

  • You might use an array to store the scores of a game, where you know that the number of players will not change.
  • You might use an ArrayList to store a list of tasks that need to be completed, where you might add or remove tasks as needed.

Ultimately, the best way to decide which data structure to use is to consider your specific needs and requirements.