Java’s Evolution: Top 5 Features from Java 8 to 22
Tags: java, javafeatures, javaevolution, java22
Published: 2024-06-14 22:03:06


## The Evolution of Java: Top 5 Features from Java 8 to Java 22

Java has continuously evolved to meet the demands of modern software development. This article explores the top 5 features introduced in each Java version from Java 8 to the latest Java 22, providing in-depth explanations, useful examples, and guidance on transitioning to the latest versions.

### Java 8: The Game Changer

Java 8, released in March 2014, marked a significant shift in the Java programming landscape with the introduction of functional programming features and the new Stream API. Here are the top 5 features of Java 8:

**Lambda Expressions**
   Lambda expressions enable you to treat functionality as a method argument or to create concise methods. For example:

   ```java
   List<String> names = Arrays.asList("Mahidhar", "Sophia", "Liam");
   names.forEach(name -> System.out.println(name));
   ```

   This feature simplifies code, making it more readable and maintainable, especially in scenarios involving collection processing.

**Stream API**
   The Stream API allows for functional-style operations on collections of objects. For instance:

   ```java
   List<String> names = Arrays.asList("Mahidhar", "Sophia", "Liam");
   List<String> sortedNames = names.stream()
                                   .sorted()
                                   .collect(Collectors.toList());
   ```

   It facilitates bulk operations on collections, such as filtering, mapping, and reducing, improving code readability and performance.

**Optional Class**
   The `Optional` class is a container object used to contain not-null objects, helping to avoid null checks. Example:

   ```java
   Optional<String> name = Optional.ofNullable("Mahidhar");
   name.ifPresent(System.out::println);
   ```

   This reduces the risk of `NullPointerException` and makes the code more expressive and intent-revealing.

**Default Methods**
   Default methods allow you to add new methods to interfaces without breaking existing implementations. Example:

   ```java
   interface Greeting {
       default void sayHello() {
           System.out.println("Hello!");
       }
   }
   ```

   This enables interface evolution by providing a way to add new methods while maintaining backward compatibility.

**Date and Time API (java.time)**
   The new Date and Time API provides a comprehensive and flexible way to handle date and time. Example:

   ```java
   LocalDate today = LocalDate.now();
   LocalDate birthday = LocalDate.of(1990, Month.JUNE, 15);
   ```

   It offers a more robust, versatile, and user-friendly approach to handling date and time compared to the old `java.util.Date` and `Calendar` classes.

### Java 9: Modularity and More

Java 9, released in September 2017, introduced the module system and several other enhancements. Here are the top 5 features of Java 9:

**Java Platform Module System (JPMS)**
   JPMS (Project Jigsaw) introduces a modular system for Java, allowing for better encapsulation and dependency management. Example:

   ```java
   module com.example.myapp {
       requires java.base;
   }
   ```

   This enhances application structure, improves security, and reduces memory footprint by enabling the creation of smaller, more efficient Java applications.

**JShell (REPL)**
   JShell provides an interactive command-line tool for learning and prototyping Java code. Example:

   ```java
   jshell> int sum(int a, int b) { return a + b; }
   jshell> sum(2, 3)
   ```

   It accelerates experimentation and learning by providing immediate feedback on code snippets.

**Factory Methods for Collections**
   Factory methods simplify the creation of immutable collections. Example:

   ```java
   List<String> names = List.of("Mahidhar", "Sophia", "Liam");
   ```

   This reduces boilerplate code and ensures that collections are immutable, enhancing code safety and clarity.

**Improved Stream API**
   Enhancements to the Stream API include methods like `takeWhile`, `dropWhile`, and `iterate`. Example:

   ```java
   Stream.of("a", "b", "c", "", "e")
         .takeWhile(s -> !s.isEmpty())
         .forEach(System.out::println);
   ```

   These provide more versatile and readable ways to manipulate streams.

**Private Interface Methods**
   Allows private methods in interfaces to share code between default methods. Example:

   ```java
   interface MyInterface {
       default void defaultMethod() {
           privateMethod();
       }
       private void privateMethod() {
           System.out.println("Private method");
       }
   }
   ```

   This promotes code reuse within interfaces, enhancing maintainability.

### Java 10: Local Variable Type Inference

Java 10, released in March 2018, brought several enhancements, with local variable type inference being the most notable. Here are the top 5 features of Java 10:

**Local Variable Type Inference (var)**
   `var` allows the compiler to infer the type of local variables, reducing boilerplate code. Example:

   ```java
   var list = List.of("Mahidhar", "Sophia", "Liam");
   for (var name : list) {
       System.out.println(name);
   }
   ```

   This improves code readability and reduces redundancy while maintaining type safety.

**Unmodifiable Collections**
   Convenience methods to create unmodifiable collections. Example:

   ```java
   var list = List.copyOf(Arrays.asList("Mahidhar", "Sophia", "Liam"));
   ```

   This simplifies the creation of immutable collections, promoting safe data handling.

**Garbage Collector (GC) Improvements**
   Introduces the G1 GC as the default garbage collector. This enhances application performance and reduces latency by improving garbage collection efficiency.

**Application Class-Data Sharing**
   Improves startup time and memory footprint by sharing common class metadata between Java processes. This optimizes resource usage, particularly in environments where multiple Java applications run simultaneously.

**Thread-Local Handshakes**
   Allows thread-local operations without global safepoints, reducing pause times. This improves performance in multi-threaded applications by minimizing synchronization overhead.

### Java 11: Long-Term Support and More

Java 11, released in September 2018, is a Long-Term Support (LTS) version, bringing numerous enhancements. Here are the top 5 features of Java 11:

**New HTTP Client**
   A new HTTP client API for handling HTTP/2 and WebSocket communication. Example:

   ```java
   HttpClient client = HttpClient.newHttpClient();
   HttpRequest request = HttpRequest.newBuilder()
                                    .uri(URI.create("https://tutorialq.com"))
                                    .build();
   HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
   System.out.println(response.body());
   ```

   This simplifies HTTP communication, supporting modern web standards and asynchronous operations.

**String Methods**
   Adds several useful methods to the `String` class, such as `isBlank`, `lines`, and `strip`. Example:

   ```java
   String multiline = "Mahidhar\nSophia\nLiam";
   multiline.lines().forEach(System.out::println);
   ```

   These enhance string manipulation capabilities, making code more expressive and concise.

**Local-Variable Syntax for Lambda Parameters**
   Allows `var` to be used in lambda expressions. Example:

   ```java
   var list = List.of("Mahidhar", "Sophia", "Liam");
   list.forEach((var name) -> System.out.println(name));
   ```

   This provides consistency in variable declaration, improving code readability.

**Epsilon Garbage Collector**
   A no-op garbage collector that handles memory allocation but does not reclaim memory. Useful for performance testing and short-lived applications where GC overhead is a concern.

**Running Java Files with `java`**
   Allows single-file source-code programs to be executed without compilation. Example:

   ```sh
   $ java HelloWorld.java
   ```

   This simplifies testing and scripting by reducing the need for explicit compilation steps.

### Java 12: Performance and Productivity

Java 12, released in March 2019, introduced several performance and productivity enhancements. Here are the top 5 features of Java 12:

**Switch Expressions (Preview)**
   Enhances switch statements with a new syntax and capabilities. Example:

   ```java
   var result = switch (day) {
       case MONDAY, FRIDAY, SUNDAY -> "Work day";
       case TUESDAY -> "Soccer day";
       default -> "Midweek day";
   };
   ```

   This simplifies complex switch logic, making code more readable and concise.

**JVM Constants API**
   Introduces an API for modeling nominal descriptions of key class-file and run-time artifacts. This facilitates the analysis and transformation of bytecode, aiding in the development of tools and frameworks.

**Default CDS Archives**
   Enables class-data sharing by default, improving startup time and memory footprint. This optimizes resource usage, particularly beneficial in containerized environments.

**Shenandoah GC (Experimental)**
   A low-pause-time garbage collector designed for large heaps. This reduces garbage collection pause times, improving performance in applications with large memory requirements.

**Microbenchmark Suite**
   Provides a set of microbenchmarks for assessing the performance of various JVM features. This helps developers understand and optimize the performance characteristics of their applications.

### Java 13: Incremental Improvements

Java 13, released in September 2019, continued the trend of incremental improvements. Here

 are the top 5 features of Java 13:

**Text Blocks (Preview)**
   Simplifies the creation of multiline strings. Example:

   ```java
   String json = """
                 {
                   "name": "Mahidhar",
                   "age": 30
                 }
                 """;
   ```

   This enhances readability and maintainability of code involving multiline strings.

**Switch Expressions (Second Preview)**
   Further refines the switch expression feature introduced in Java 12. This continues to simplify and modernize switch statements, improving code clarity.

**Reimplementation of the Legacy Socket API**
   Replaces the underlying implementation of the legacy socket API to improve performance and maintainability. This enhances network communication performance and reliability.

**Dynamic CDS Archives**
   Extends class-data sharing to dynamically loaded classes. This further reduces startup time and memory usage by sharing more class data between applications.

**ZGC: Uncommit Unused Memory**
   Enhances the Z Garbage Collector to return unused memory to the operating system. This optimizes memory usage, particularly in environments with fluctuating memory demands.

### Java 14: Productivity and Syntax

Java 14, released in March 2020, focused on productivity and syntactic enhancements. Here are the top 5 features of Java 14:

**Switch Expressions (Standard)**
   Finalizes the switch expression feature, making it a standard language feature. Example:

   ```java
   var result = switch (day) {
       case MONDAY, FRIDAY, SUNDAY -> "Work day";
       case TUESDAY -> "Soccer day";
       default -> "Midweek day";
   };
   ```

   This simplifies complex switch logic, improving code readability.

**Records (Preview)**
   Introduces records, a new way to declare data classes. Example:

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

   This reduces boilerplate code for data carriers, improving code simplicity and readability.

**Pattern Matching for instanceof (Preview)**
   Simplifies type checks and casts. Example:

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

   This reduces boilerplate code, making type checks and casts more concise and readable.

**Helpful NullPointerExceptions**
   Enhances `NullPointerException` messages to include details about what was `null`. This improves debugging efficiency by providing more informative error messages.

**Non-Volatile Mapped Byte Buffers**
   Improves the performance and reliability of file I/O operations. This enhances file I/O operations, particularly in applications dealing with large files or high I/O demands.

### Java 15: Language and Runtime Enhancements

Java 15, released in September 2020, introduced several language and runtime enhancements. Here are the top 5 features of Java 15:

**Text Blocks (Standard)**
   Finalizes the text block feature, making it a standard language feature. Example:

   ```java
   String json = """
                 {
                   "name": "Mahidhar",
                   "age": 30
                 }
                 """;
   ```

   This simplifies the creation and maintenance of multiline strings.

**Sealed Classes (Preview)**
   Allows the declaration of sealed classes, restricting which classes can extend or implement them. Example:

   ```java
   public abstract sealed class Shape
       permits Circle, Square, Rectangle {}
   ```

   This provides more control over class hierarchies, enhancing code safety and maintainability.

**Hidden Classes**
   Introduces hidden classes, intended for use by frameworks that generate classes at runtime. This improves performance and security for runtime-generated classes.

**Pattern Matching for instanceof (Second Preview)**
   Further refines the pattern matching for `instanceof` feature. This continues to simplify type checks and casts, improving code readability.

**ZGC: Concurrent Class Unloading**
   Enhances the Z Garbage Collector to unload classes concurrently, improving performance. This optimizes memory usage and performance in applications with dynamic class loading.

### Java 16: Improved Productivity and Performance

Java 16, released in March 2021, brought several productivity and performance enhancements. Here are the top 5 features of Java 16:

**Records (Standard)**
   Finalizes the record feature, making it a standard language feature. Example:

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

   This reduces boilerplate code for data carriers, improving code simplicity and readability.

**Pattern Matching for instanceof (Standard)**
   Finalizes the pattern matching for `instanceof` feature. Example:

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

   This reduces boilerplate code, making type checks and casts more concise and readable.

**Sealed Classes (Second Preview)**
   Further refines the sealed classes feature. This continues to provide more control over class hierarchies, enhancing code safety and maintainability.

**Foreign-Memory Access API (Incubator)**
   Introduces an API for accessing foreign memory outside the Java heap. This facilitates the development of high-performance, memory-efficient applications that interact with native memory.

**Packaging Tool**
   Provides a tool for packaging self-contained Java applications. This simplifies the distribution and deployment of Java applications, particularly in containerized environments.

### Java 17: Long-Term Support and More

Java 17, released in September 2021, is a Long-Term Support (LTS) version, bringing numerous enhancements. Here are the top 5 features of Java 17:

**Sealed Classes (Standard)**
   Finalizes the sealed classes feature, making it a standard language feature. Example:

   ```java
   public abstract sealed class Shape
       permits Circle, Square, Rectangle {}
   ```

   This provides more control over class hierarchies, enhancing code safety and maintainability.

**Pattern Matching for switch (Preview)**
   Introduces pattern matching for switch statements. Example:

   ```java
   switch (obj) {
       case String s -> System.out.println("String: " + s);
       case Integer i -> System.out.println("Integer: " + i);
       default -> System.out.println("Unknown type");
   }
   ```

   This simplifies complex switch logic, improving code readability.

**Foreign Function & Memory API (Incubator)**
   Introduces an API for calling native functions and accessing native memory. This facilitates the development of high-performance, memory-efficient applications that interact with native code.

**Context-Specific Deserialization Filters**
   Enhances security by allowing context-specific deserialization filters. This improves security by providing fine-grained control over deserialization operations.

**New macOS Rendering Pipeline**
   Introduces a new rendering pipeline for macOS based on the Apple Metal framework. This improves graphics performance and compatibility on macOS.

### Java 18: Performance and Simplicity

Java 18, released in March 2022, focused on performance and simplicity. Here are the top 5 features of Java 18:

**UTF-8 by Default**
   Sets UTF-8 as the default character set for the Java runtime. This ensures consistent handling of character data across different platforms.

**Simple Web Server**
   Introduces a simple web server for prototyping and testing. Example:

   ```java
   jwebserver --port 8080
   ```

   This simplifies the development and testing of web applications.

**Code Snippets in Java API Documentation**
   Enhances API documentation with code snippets. This improves the usability and understanding of Java APIs.

**Vector API (Third Incubator)**
   Introduces a vector API for expressing vector computations. This facilitates the development of high-performance, data-parallel applications.

**Foreign Function & Memory API (Second Incubator)**
   Further refines the foreign function and memory API. This continues to facilitate the development of high-performance, memory-efficient applications that interact with native code.

### Java 19: Enhanced Performance and Productivity

Java 19, released in September 2022, brought several performance and productivity enhancements. Here are the top 5 features of Java 19:

**Virtual Threads (Preview)**
   Introduces virtual threads for lightweight concurrency. This simplifies the development of high-concurrency applications by reducing the overhead of thread management.

**Pattern Matching for switch (Second Preview)**
   Further refines the pattern matching for switch statements. This continues to simplify complex switch logic, improving code readability.

**Structured Concurrency (Incubator)**
   Introduces an API for structured concurrency, making it easier to manage multiple tasks. This improves code reliability and readability by providing a structured approach to concurrency.

**Foreign Function & Memory API (Third Incubator)**
   Further refines the foreign function and memory API. This continues to facilitate the development of high-performance, memory-efficient applications that interact with native code.

**Linux/RISC-V Port**
   Adds support for the Linux/RISC-V architecture. This expands the platform support for Java, making it available on more hardware configurations.

### Java 20: Language and Performance Enhancements

Java 20, released in March 2023, focused on language and performance enhancements. Here are the top 5 features of Java 20:

**Virtual Threads (Second Preview)**
   Further refines the virtual threads feature for lightweight concurrency. This continues to simplify the development of high-concurrency applications.

**Pattern Matching for switch (Third Preview)**
   Further refines the pattern matching for switch statements. This continues to simplify complex switch logic, improving code readability.

**Record Patterns (Preview)**


   Introduces record patterns for pattern matching with records. Example:

   ```java
   record Point(int x, int y) {}
   switch (obj) {
       case Point(var x, var y) -> System.out.println("Point: (" + x + ", " + y + ")");
       default -> System.out.println("Unknown type");
   }
   ```

   This simplifies pattern matching with record classes, enhancing code readability.

**Foreign Function & Memory API (Fourth Incubator)**
   Further refines the foreign function and memory API. This continues to facilitate the development of high-performance, memory-efficient applications that interact with native code.

**Scoped Values (Incubator)**
   Introduces scoped values for safe and efficient sharing of immutable data within and across threads. This enhances concurrency handling by providing a mechanism for thread-local data sharing.

### Java 21: Long-Term Support and More

Java 21, released in September 2023, is a Long-Term Support (LTS) version, bringing numerous enhancements. Here are the top 5 features of Java 21:

**Virtual Threads (Standard)**
   Finalizes the virtual threads feature, making it a standard concurrency model. This simplifies the development of high-concurrency applications by reducing the overhead of thread management.

**Pattern Matching for switch (Fourth Preview)**
   Further refines the pattern matching for switch statements. This continues to simplify complex switch logic, improving code readability.

**Record Patterns (Second Preview)**
   Further refines record patterns for pattern matching with records. This continues to simplify pattern matching with record classes, enhancing code readability.

**Foreign Function & Memory API (Fifth Incubator)**
   Further refines the foreign function and memory API. This continues to facilitate the development of high-performance, memory-efficient applications that interact with native code.

**Sequenced Collections**
   Introduces sequenced collections to provide a common interface for collections with a defined iteration order. Example:

   ```java
   SequencedCollection<String> seq = SequencedCollections.of("Mahidhar", "Sophia", "Liam");
   seq.forEach(System.out::println);
   ```

   This standardizes the iteration order, improving code predictability and reliability.

### Java 22: Latest Innovations

Java 22, released in March 2024, continues to build on the advancements of previous versions. Here are the top 5 features of Java 22:

**Enhanced Pattern Matching**
   Extends pattern matching to more contexts, providing greater flexibility and expressiveness. Example:

   ```java
   switch (obj) {
       case String s && s.length() > 5 -> System.out.println("Long string: " + s);
       case Integer i && i > 10 -> System.out.println("Large number: " + i);
       default -> System.out.println("Other type");
   }
   ```

   This enhances code readability and maintainability by allowing more complex conditions in pattern matching.

**Universal Generics**
   Introduces universal generics to simplify generic type declarations and improve type safety. Example:

   ```java
   class Box<T extends Number> {
       private T value;
       public Box(T value) {
           this.value = value;
       }
       public T getValue() {
           return value;
       }
   }
   ```

   This improves code reusability and type safety by allowing more flexible and powerful generic type declarations.

**Improved JSON Handling**
   Enhances JSON handling capabilities with new APIs and improvements to existing ones. Example:

   ```java
   JsonObject json = Json.createObjectBuilder()
                         .add("name", "Mahidhar")
                         .add("age", 30)
                         .build();
   System.out.println(json.toString());
   ```

   This simplifies working with JSON data, making it more efficient and intuitive.

**Optimized Garbage Collection**
   Introduces further optimizations to garbage collection, reducing latency and improving performance. This enhances application responsiveness and stability, particularly in memory-intensive scenarios.

**Advanced Networking Features**
   Adds advanced networking features to support the latest protocols and improve network performance. Example:

   ```java
   HttpClient client = HttpClient.newBuilder()
                                 .version(HttpClient.Version.HTTP_2)
                                 .build();
   HttpRequest request = HttpRequest.newBuilder()
                                    .uri(URI.create("https://tutorialq.com"))
                                    .build();
   HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
   System.out.println(response.body());
   ```
This supports modern networking standards, improving application performance and interoperability.

Migrating to Java 17 or higher can bring significant benefits, but it also comes with challenges. Here are the top 5 issues you might encounter:

### 1. **Compatibility Issues**
   - **Description**: Some libraries and frameworks may not be fully compatible with Java 17 or higher. This is particularly relevant for older or less-maintained dependencies.
   - **Example**: If you are using an older version of a library that relies on deprecated or removed APIs, you may encounter compilation or runtime errors.
   - **Solution**: Update all dependencies to their latest versions and check for compatibility with Java 17. Utilize tools like `jdeps` to analyze your dependencies and identify potential issues.

### 2. **Removed and Deprecated APIs**
   - **Description**: Java 17 and higher have removed several APIs and features that were deprecated in previous versions. This can cause compilation errors if your code relies on these APIs.
   - **Example**: The removal of the `Applets` API and the `Security Manager` can impact applications that still use these features.
   - **Solution**: Refactor your code to replace deprecated APIs with their modern equivalents. Review the release notes for each Java version to understand which features have been removed and plan accordingly.

### 3. **Module System (JPMS)**
   - **Description**: The introduction of the Java Platform Module System (JPMS) in Java 9 can complicate the migration process, especially for large, monolithic applications.
   - **Example**: Splitting a large codebase into modules and ensuring that dependencies are properly managed can be challenging.
   - **Solution**: Start by modularizing the most critical parts of your application and gradually refactor the rest. Use `jdeps` to help identify module dependencies and create module descriptors (`module-info.java`).

### 4. **New Garbage Collection Behavior**
   - **Description**: Changes and improvements to garbage collection (GC) algorithms in newer Java versions can impact application performance and behavior.
   - **Example**: The G1 garbage collector became the default in Java 9, and Java 17 includes further improvements. Applications with specific performance tuning for older GCs might need re-tuning.
   - **Solution**: Test your application thoroughly with the new GC settings. Profile and monitor performance, and adjust GC tuning parameters as needed.

### 5. **Java Language and Syntax Changes**
   - **Description**: New language features and syntax changes introduced in Java 17 and higher, such as records, sealed classes, and pattern matching, can require significant refactoring of your codebase.
   - **Example**: Adopting new features like records and pattern matching might necessitate changes in your data classes and how you handle certain operations.
   - **Solution**: Plan for incremental adoption of new language features. Ensure your development team is familiar with the latest Java enhancements and provide training if necessary.

### Additional Tips for a Smooth Migration
- **Automated Testing**: Ensure comprehensive automated tests are in place to quickly identify issues introduced by the migration.
- **CI/CD Pipeline**: Utilize continuous integration and continuous deployment pipelines to streamline the migration process and catch issues early.
- **Performance Testing**: Conduct thorough performance testing to identify any regressions and optimize accordingly.
- **Documentation**: Keep detailed documentation of the migration process, issues encountered, and solutions implemented to assist future migrations.

By being aware of these potential issues and planning accordingly, you can make your migration to Java 17 or higher smoother and more successful.