Top 5 Features of Java 17 this is test

1. Sealed Classes 

Sealed classes let you control which classes can extend your class. This adds more safety to your design.

Sealed class prevents unwanted extension and enforces tighter class hierarchies.

public sealed class Vehicle permits Car, Bike {} 

final class Car extends Vehicle {} 
final class Bike extends Vehicle {}
  

Car and Bike can extend Vehicle, preventing unwanted class extensions.

2. Pattern Matching for instance of 

No more unnecessary casting after checking types!

if (obj instanceof String s) { 
    System.out.println(s.toUpperCase()); 
}    
  

3. Text Blocks  

Writing multi-line strings is now much easier.

It improves readability, especially for JSON, HTML, or SQL.

String json = """ 
    { 
        "name": "Java", 
        "version": 17 
    } 
    """;    
  

4. Switch Expressions 

Now you can return values directly from a switch expression. This makes switch cases less error-prone and more concise. 

It improves readability, especially for JSON, HTML, or SQL.

String result = switch (day) { 
    case "MONDAY", "FRIDAY" -> "Workday"; 
    case "SATURDAY", "SUNDAY" -> "Weekend"; 
    default -> "Unknown"; 
};    
  

5. Record Classes 

Record is a special type in Java used for creating data-holding classes with very little code. It’s perfect for DTOs (Data    Transfer Objects).

What it does:

Automatically generates constructor, getters, toString(), equals(), and hashCode(). 
Helps avoid boilerplate when you just need to store data. 

public record Person(String name, int age) {} 

public class Main { 
    public static void main(String[] args) { 
        Person p = new Person("Alice", 30); 
        System.out.println(p.name()); // Alice 
        System.out.println(p.age());  // 30 
    } 
}