HashMap
The HashMap class in Java is an implementation of the Map interface that stores key-value pairs. It provides fast access and retrieval of elements based on their keys.
To use the HashMap class, you need to import the java.util.HashMap package.
Here's an example that demonstrates the usage of the HashMap class:
TEXT/X-JAVA
1class Main {
2
3 public static void main(String[] args) {
4 // Create a HashMap
5 HashMap<String, Integer> hashMap = new HashMap<>();
6
7 // Add key-value pairs to the HashMap
8 hashMap.put("John", 25);
9 hashMap.put("Sarah", 30);
10 hashMap.put("Emily", 28);
11
12 // Access values from the HashMap
13 int johnAge = hashMap.get("John");
14 System.out.println("John's age: " + johnAge);
15
16 // Check if a key exists in the HashMap
17 boolean exists = hashMap.containsKey("Sarah");
18 System.out.println("Sarah exists: " + exists);
19
20 // Remove a key-value pair from the HashMap
21 hashMap.remove("Emily");
22
23 // Update the value for a key in the HashMap
24 hashMap.put("John", 26);
25
26 // Get the size of the HashMap
27 int size = hashMap.size();
28 System.out.println("Size of the HashMap: " + size);
29 }
30
31}xxxxxxxxxx33
}import java.util.HashMap;public class Main { public static void main(String[] args) { // Create a HashMap HashMap<String, Integer> hashMap = new HashMap<>(); // Add key-value pairs to the HashMap hashMap.put("John", 25); hashMap.put("Sarah", 30); hashMap.put("Emily", 28); // Access values from the HashMap int johnAge = hashMap.get("John"); System.out.println("John's age: " + johnAge); // Check if a key exists in the HashMap boolean exists = hashMap.containsKey("Sarah"); System.out.println("Sarah exists: " + exists); // Remove a key-value pair from the HashMap hashMap.remove("Emily"); // Update the value for a key in the HashMap hashMap.put("John", 26); // Get the size of the HashMap int size = hashMap.size();OUTPUT
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