💛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.
💛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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