Array in C refers to clubbing multiple similar entities together into a larger group in contiguous memory locations. These entities can belong to any data type, however in order to be stored together, they need to belong to the same data type. The ‘n’ elements are stored from left to right, with index numbers beginning from 0 and ending at n-1. Arrays are used to structurally organise and store a large number of variables. Array in C is a very important data structure and is widely used for various programming-related tasks. So if you need to store 500 variables, create an array of size 500, and store all the 500 variables in the array using a loop, thus enabling the storage of variables of a large amount in a single array in a more optimised manner.
ArrayList is a data structure in the java language which represents a resizeable array of objects. ArrayList implements the ‘list’ interface, belonging to ‘java.util’. The list can grow or shrink in size as elements are removed or added to the list, which is convenient when you add or remove elements you need to store as and when the data changes over time. ArrayList provides a number of methods to add, remove, retrieve, and manipulate elements in the list, such as add(), remove(), get(), set(), indexOf(), size(), isEmpty(), contains(), and many others.
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Last Updated: 2022-04-21
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Difference between Array and an ArrayList:
Arrays and ArrayList are used to store data collections, but there are a few key differences between them:
| Properties | Array | ArrayList |
|---|---|---|
| Size | Arrays size is fixed when created | ArrayList can grow or shrink as and when elements are added or removed |
| Type | Arrays can store primitive data structures like int, char, str, and objects. | ArrayList can only store objects. |
| Access | You can have direct access to the elements by calling out the index. | ArrayList requires ‘get()’ and ‘set()’ to access the elements in the list, |
| Memory | Memory is efficient as they don’t have the overhead of resizing the array | Less efficient than Array. |
| Speed | Faster for smaller collections. | If you are dealing with large collections with frequent resizing, you use ArrayList. |
| Dimensions | Arrays don’t allow generics through multidimensional in nature. | ArrayList allows the use of generics and is single-dimensional in nature. |
| Functions supported | Functions like indexOf() or remove() are not supported by Array. | Functions like indexOf() or remove() are supported by ArrayList. |
| Declaration and Initialization | Here is the code to declare and initialise in an array in Java: int[] myArray = { 1, 2, 3, 4, 5 }; | Here is the code to declare and initialise in an ArrayList in Java: import java.util.ArrayList; ArrayList String myList = new ArrayList String(); myList.add(“Alice”); myList.add(“Bob”); myList.add(“Charlie”); |
| Functionality in Java | You can access elements in Array using [] | You can access elements in ArrayList using a set of methods to modify elements. |
| Data Structure | The size has to be mentioned as Array has a fixed structure. | Elements can be added in ArrayList though some initial elements need to be mentioned. |