💛Implementation of Map Interface💚

💛Implementation of Map Interface💚

Let's discuss HashMap, LinkedHashMap, and TreeMap in Java, along with real-time examples and when to use each of them.

✅ HashMap 🔴

It is a basic implementation of the Map interface in Java. It stores key-value pairs and uses a hash table to provide constant-time complexity for basic operations like get and put.

👉 Real-time Example:

Storing and retrieving student grades by using the student's roll number as the key and their grade as the value.

👉 Code Example:

// Creating a HashMap

Map<Integer, String> stuGrades = new HashMap<>();

// Adding data

stuGrades.put(101, "A");

stuGrades.put(102, "B");

// Retrieving data

String grade = stuGrades.get(101); // Returns "A"

👉 When to Use:

Use HashMap when you need a simple key-value store with fast retrieval and you don't require any specific order for the keys.

✅ LinkedHashMap 🔴

LinkedHashMap extends HashMap and maintains the order of elements in which they were inserted. It's implemented as a doubly-linked list with a hash table.

👉 Real-time Example:

Maintaining a shopping cart with products and their quantities, where the order of adding products matters.

👉 Code Example:

// Create a LinkedHashMap

Map<String, Integer> shoppingCart = new LinkedHashMap<>();

// Adding data

shoppingCart.put("Laptop", 2);

// Iterating in insertion order

for (Map.Entry<String, Integer> entry : shoppingCart.entrySet()) {

Sysout(entry.getKey()+ entry.getValue());

}

👉 When to Use:

Use LinkedHashMap when you need to maintain the order of elements as they were inserted, such as in scenarios where insertion order matters.

✅ TreeMap: 🔴

It is a Red-Black tree-based implementation of the Map interface. It maintains keys in sorted order, which allows for efficient range queries and ordered traversal of keys.

👉 Real-time Example:

Maintaining a dictionary of words and their meanings, where you want to look up words in alphabetical order.

👉 Code Example:

// Creating a TreeMap

Map<String, String> dictionary = new TreeMap<>();

// Adding data

dictionary.put("apple", "a fruit");

dictionary.put("banana", "a tropical fruit");

// Iterating in sorted order

for (Map.Entry<String, String> entry : dictionary.entrySet()) {

Sysout(entry.getKey()+ entry.getValue());

}

👉 When to Use:

Use TreeMap when you need to maintain keys in sorted order and perform operations like range queries or ordered traversal. Be aware that TreeMap has a slightly slower performance compared to HashMap and LinkedHashMap due to the sorting overhead.

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