Java 17 vs Java 8: New Features, Performance Boosts, and Code Samples

Java 17 vs Java 8 Overview

Java is a popular, cross‑platform language. Java 8 was released in March 2014, introducing lambdas, Stream API, and other functional features. Java 17, released September 2021, is the next LTS version with many enhancements.

Key Differences

Java 17 introduces the ZGC garbage collector (with options Shenandoah, G1, Parallel, Serial), supports Application Class Data Sharing (AppCDS), provides asynchronous JFR event handling, and adds new cryptographic algorithms (SHA‑3, SM3/SM4, Ed448, RSASSA‑PSS, X25519/X448). Java 8 uses the G1 collector, lacks AppCDS and JFR support, and relies on older algorithms (SHA‑1, RC4, DES, MD5, DSA, DH).

Performance Improvements

Enhanced JIT compiler for faster execution.

Improved garbage collectors delivering higher throughput.

C++‑style memory management optimizations.

Language Feature Enhancements

Sealed classes to restrict inheritance.

Pattern‑matching for switch statements.

Record classes for concise data carriers.

New Features with Code Samples

Sealed Classes

public sealed abstract class Shape permits Circle, Rectangle {
    public abstract double calculateArea();
}
public final class Circle extends Shape {
    private double radius;
    public Circle(double radius) { this.radius = radius; }
    public double calculateArea() { return Math.PI * radius * radius; }
}
public final class Rectangle extends Shape {
    private double length;
    private double width;
    public Rectangle(double length, double width) {
        this.length = length; this.width = width;
    }
    public double calculateArea() { return length * width; }
}

Pattern Matching for Switch

public static void main(String[] args) {
    Object obj = "hello";
    switch (obj) {
        case String s && s.length() > 5 -> System.out.println("Long string");
        case String s -> System.out.println("Short string");
        case Integer i -> System.out.println("Integer");
        default -> System.out.println("Unsupported type");
    }
}

Record Classes

public record Person(String name, int age) {}
public class RecordExample {
    public static void main(String[] args) {
        Person person = new Person("John", 30);
        System.out.println("Name: " + person.name());
        System.out.println("Age: " + person.age());
    }
}

Improved Garbage Collector Example

public class GarbageCollectorExample {
    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < 1_000_000; i++) {
            list.add(i);
        }
        System.out.println("List size: " + list.size());
        System.gc();
        System.out.println("List size after GC: " + list.size());
    }
}

JIT Compiler Example

public class JITCompilerExample {
    public static void main(String[] args) {
        int sum = 0;
        for (int i = 0; i < 1_000_000; i++) {
            sum += i;
        }
        System.out.println("Sum is: " + sum);
    }
}

Enhanced Collections API

Java 17 adds convenient factory methods such as List.of(...), Set.of(...), and Map.of(...), as well as stream operations like takeWhile, dropWhile, and improved Collectors utilities.