Introduction:
When programming in Java, we often need to store collections of data in memory. Arrays are one way to do this, but they have a fixed size, making it difficult to add or remove elements as needed. To solve this problem, we can use dynamic data structures like ArrayList and LinkedList. In this article, we'll explore the differences between these two classes and when you might want to use one over the other.
Code Examples:
Let's take a closer look at ArrayList and LinkedList by examining some code examples.
ArrayList is a part of the Java Collection Framework and provides us with dynamic arrays in Java. Here's an example:
// Create an ArrayList of integers
ArrayList<Integer> arrayList = new ArrayList<Integer>();
// Add elements to the ArrayList
arrayList.add(1);
arrayList.add(2);
arrayList.add(3);
In this example, we create an empty ArrayList that can store integers. We then add three integers to the ArrayList using the add() method. One benefit of ArrayList is that it automatically resizes itself when new elements are added.
LinkedList, on the other hand, is a linear data structure where elements are not stored in contiguous locations. Instead, each element is a separate object with a data part and an address part. Here's an example:
// Create a LinkedList of strings
LinkedList<String> linkedList = new LinkedList<String>();
// Add elements to the LinkedList
linkedList.add("one");
linkedList.add("two");
linkedList.add("three");
In this example, we create an empty LinkedList that can store strings. We then add three strings to the LinkedList using the add() method. Unlike ArrayList, LinkedList elements are linked using pointers and addresses.
Pros and Cons:
Now that we've seen some examples, let's compare the pros and cons of ArrayList and LinkedList.
ArrayList:
Pros:
- This class uses a dynamic array to store the elements in it.
- With the introduction of generics, this class supports the storage of all types of objects.
- Accessing elements is faster in ArrayList than LinkedList.
Cons:
- Manipulating ArrayList takes more time due to the internal implementation.
- Whenever we remove an element, internally, the array is traversed and the memory bits are shifted.
- This class works better when the application demands storing the data and accessing it.
LinkedList:
Pros:
- This class uses a doubly linked list to store the elements in it.
- Similar to the ArrayList, this class also supports the storage of all types of objects.
- Manipulating LinkedList takes less time compared to ArrayList.
Cons:
Accessing elements is slower in LinkedList than ArrayList.
This class works better when the application demands manipulation of the stored data.
Use Cases:
When should you use ArrayList over LinkedList, and vice versa? Here are some examples:
ArrayList:
- When the application needs to access elements frequently.
- When the application needs to iterate over the collection frequently.
- When the application needs to add or remove elements less frequently.
LinkedList:
- When the application needs to add or remove elements frequently.
- When the application needs to manipulate the collection frequently.
Conclusion:
In conclusion, ArrayList and LinkedList are both dynamic data structures that can be used to store collections of data in Java. While ArrayList is better suited for storing and accessing elements, LinkedList is better suited for frequent manipulation of the collection. By understanding the pros and cons of each, you can choose the one that best fits your application's needs.
