What are the key data structures and algorithms in Java?

What are the key data structures and algorithms in Java?

In Java, key data structures include Arrays, Linked Lists, Stacks, Queues, Trees, and HashMaps. Algorithms often involve sorting (like QuickSort, MergeSort) and searching (like Binary Search). Would you like to dive deeper into any specific structure or algorithm?

Can you explain how a HashMap works?

A HashMap in Java stores key-value pairs. It uses a hash function to compute an index into an array of buckets, from which the desired value can be found. This allows for average-case constant time complexity for get and put operations. Would you like to see an example?

Yes, please provide a code example.

Sure! Here's a simple example:

import java.util.HashMap;

public class Main {
    public static void main(String[] args) {
        HashMap<String, Integer> map = new HashMap<>();
        map.put("Apple", 1);
        map.put("Banana", 2);
        System.out.println(map.get("Apple")); // Output: 1
    }
}

This code creates a HashMap, adds some key-value pairs, and retrieves a value using a key.

What are the advantages of using a Linked List over an Array?

Linked Lists offer dynamic sizing, allowing for efficient insertions and deletions without reallocating or resizing the entire structure, unlike Arrays. However, they have higher memory overhead and slower access times due to non-contiguous memory allocation.