How do I use the collections framework in Java?

How do I use the collections framework in Java?

The collections framework in Java provides a set of classes and interfaces for storing and manipulating groups of data. You can use classes like ArrayList, HashSet, and HashMap to manage collections of objects.

Can you give me an example of using an ArrayList?

Sure! Here's a simple example:

import java.util.ArrayList;

public class Main {
    public static void main(String[] args) {
        ArrayList<String> fruits = new ArrayList<>();
        fruits.add("Apple");
        fruits.add("Banana");
        fruits.add("Cherry");
        System.out.println(fruits);
    }
}

This code creates an ArrayList of fruits and prints it.

What are the differences between ArrayList and LinkedList?

ArrayList is backed by a dynamic array, which makes it faster for random access but slower for insertions and deletions. LinkedList, on the other hand, is a doubly-linked list, which allows for faster insertions and deletions but slower random access.

When should I use a HashMap?

Use a HashMap when you need to store key-value pairs and require fast lookups, insertions, and deletions. It's particularly useful when you need to associate unique keys with values.