Java 8 vs Java 17: Key Differences and When to Use Each

Java 8 introduced major features like lambda expressions and Stream API, while Java 17, a long-term support release, adds modern features like sealed classes, pattern matching, and improved performance. Java 17 also includes enhanced APIs and better support for modern development compared to Java 8.

Quick Comparison

This table summarizes key differences between Java 8 and Java 17.

Feature	Java 8	Java 17
Release Year	2014	2021
Lambda Expressions & Streams	Introduced	Supported with improvements
Pattern Matching	Not available	Supported for instanceof and switch
Sealed Classes	Not available	Supported for controlled inheritance
Records (Data Classes)	Not available	Supported for concise data carriers
Long-Term Support (LTS)	Yes	Yes (latest LTS)
Performance & JVM Improvements	Standard JVM	Enhanced JVM with better GC and performance

Key Differences

Java 8 was a landmark release that introduced lambda expressions and the Stream API, enabling functional-style programming and easier collection processing. It also added the java.time package for better date and time handling.

Java 17 builds on these foundations with modern language features like sealed classes that restrict which classes can extend or implement them, improving code safety and design. It also introduces pattern matching for instanceof and switch statements, making type checks and data extraction simpler and more readable.

Additionally, Java 17 includes records, a concise way to declare immutable data classes without boilerplate code. The JVM itself has seen many performance improvements, including better garbage collection algorithms and startup times, making Java 17 more efficient for modern applications.

Code Comparison

java

import java.util.List;
import java.util.stream.Collectors;

public class Java8Example {
    public static void main(String[] args) {
        List<String> names = List.of("Anna", "Bob", "Charlie", "David");
        // Filter names starting with 'A' and convert to uppercase
        List<String> filtered = names.stream()
            .filter(name -> name.startsWith("A"))
            .map(String::toUpperCase)
            .collect(Collectors.toList());
        System.out.println(filtered);
    }
}

Output

[ANNA]

Java 17 Equivalent

java

import java.util.List;
import java.util.stream.Collectors;

public class Java17Example {
    public static void main(String[] args) {
        List<String> names = List.of("Anna", "Bob", "Charlie", "David");
        // Using pattern matching in switch (Java 17 feature)
        List<String> filtered = names.stream()
            .filter(name -> switch (name) {
                case String s && s.startsWith("A") -> true;
                default -> false;
            })
            .map(String::toUpperCase)
            .collect(Collectors.toList());
        System.out.println(filtered);
    }
}

Output

[ANNA]

When to Use Which

Choose Java 8 if you need stable, widely supported LTS with compatibility for older libraries and environments. It is suitable for projects that rely on legacy systems or require broad compatibility.

Choose Java 17 for new projects or when upgrading, to benefit from modern language features like sealed classes, records, and improved JVM performance. Java 17 is ideal for writing cleaner, safer code and leveraging the latest Java ecosystem improvements.

Key Takeaways

Java 8 introduced lambdas and streams, revolutionizing Java programming style.

Java 17 adds modern features like sealed classes, pattern matching, and records for cleaner code.

Java 17 offers better JVM performance and is the latest long-term support version.

Use Java 8 for legacy compatibility and Java 17 for modern development and improved efficiency.