Transitioning from Java 8 to Java 17

Introduction:

Transitioning from Java 8 to Java 17 marks a significant leap forward, unlocking a wealth of new possibilities and enhancements. This guide delves into the key changes and new features introduced in Java versions spanning from 8 to 17.

Key Changes and New Features:

The journey from Java 8 to Java 17 unfolds a multitude of transformative enhancements across language constructs, APIs, and performance optimizations. Let's explore these changes in depth:

Language Enhancements:

Pattern Matching for Switch (Java 17): Pattern matching, introduced in Java 17, simplifies code by enabling concise conditional logic within switch statements. It eliminates the need for explicit type casting. Consider the following example:
```
  // Java 17
  Object obj = "Hello";
  if (obj instanceof String s) {
      System.out.println(s.length()); // No need to cast 's' to String
  } else {
      System.out.println("Not a string");
  }
```

Records (Java 14, Enhanced in Java 17): Records offer a compact syntax for declaring immutable data classes. In Java 17, records can include additional methods or constructor logic, enhancing their versatility. Here's an example:

  // Java 14
  record Person(String name, int age) {}

  // Java 17 (Enhanced records)
  record Person(String name, int age) {
      public String getNameWithAge() {
          return name + " is " + age + " years old";
      }
  }

Text Blocks (Java 15): Text blocks provide a more readable way to represent multi-line strings in Java. They simplify the formatting of complex string literals. Consider the following example:

  // Java 15
  String html = """
                <html>
                    <body>
                        <p>Hello, world!</p>
                    </body>
                </html>
                """;

API Changes and Enhancements:
- Sealed Classes and Interfaces (Java 17): Sealed classes and interfaces restrict which other classes or interfaces may extend or implement them. This enhances code maintainability and security by controlling the inheritance hierarchy. Here's an example:
```
  // Java 17
  sealed interface Shape permits Circle, Rectangle {
      double area();
  }
```
- Convenience Factory Methods for Collections (Java 9): Java 9 introduced factory methods for creating immutable collections, offering a concise and convenient way to instantiate collections. Example:
```
  // Java 9
  List<Integer> list = List.of(1, 2, 3);
```
- Optional Enhancements (Java 9): Java 9 introduced several enhancements to the Optional class, including ifPresentOrElse, stream, or, and ifPresentOrElse. Example:
```
  // Java 9
  Optional<String> optional = Optional.of("Hello");
  optional.ifPresentOrElse(
      value -> System.out.println("Value: " + value),
      () -> System.out.println("Value not present")
  );
```
Performance Improvements:
- JVM Enhancements: Each new release typically brings optimizations to the Java Virtual Machine (JVM) and runtime libraries, resulting in improved performance.
- Stream API Enhancements (Java 9): Java 9 introduced enhancements to the Stream API, including takeWhile, dropWhile, and ofNullable, offering more powerful stream processing capabilities. Example:
```
  // Java 9
  List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
  List<Integer> evenNumbers = numbers.stream()
                                      .takeWhile(n -> n % 2 == 0)
                                      .collect(Collectors.toList());
```
Tooling and Ecosystem:
- Compatibility: Ensure compatibility of development environments, libraries, and frameworks with Java 17.
- Update Build Tools and IDEs: Update build tools (e.g., Maven, Gradle) and Integrated Development Environments (IDEs) to versions compatible with Java 17.

Transitioning from Java 8 to Java 17

Table of contents

Introduction:

Key Changes and New Features: