Java 15 New Features: Enhancements for Developers

Java 15 introduced several new features and enhancements that improve performance, security, and developer productivity. This post summarizes the main points to help developers leverage these updates effectively.

1. Sealed Classes

What are Sealed Classes?

Sealed classes allow developers to control which classes can inherit from them.

Benefits:

• Provides better control over class hierarchies.
• Enhances security and maintainability of code.

Example:

sealed class Shape permits Circle, Square {
    // Class body
}

final class Circle extends Shape {
    // Class body
}

final class Square extends Shape {
    // Class body
}

2. Records

What are Records?

Records are a new type of class that act as transparent carriers for immutable data.

Benefits:

• Reduces boilerplate code by automatically generating methods like equals(), hashCode(), and toString().

Example:

record Point(int x, int y) {}

Point p = new Point(10, 20);
System.out.println(p); // Output: Point[x=10, y=20]

3. Text Blocks

What are Text Blocks?

Text blocks allow multi-line string literals, improving readability.

Benefits:

• Simplifies the creation of strings that span multiple lines, such as JSON or SQL.

Example:

String json = """
    {
        "name": "John",
        "age": 30
    }
""";

4. Pattern Matching for instanceof

What is Pattern Matching?

A simplified way to check if an object is an instance of a specific class and cast it.

Benefits:

• Reduces boilerplate code and enhances readability.

Example:

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

5. New Z Garbage Collector

What is ZGC?

A low-latency garbage collector designed to handle large heap sizes with minimal pause times.

Benefits:

• Improves application performance, especially for large-scale applications.

6. Hidden Classes

What are Hidden Classes?

Classes that are not accessible from the classpath and are intended for use by frameworks that generate classes at runtime.

Benefits:

• Enhances security and performance for dynamic language features.

Conclusion

Java 15 brings significant improvements that enhance the language's usability and performance. The introduction of sealed classes, records, text blocks, pattern matching, the Z Garbage Collector, and hidden classes are key features that developers can leverage for cleaner, more efficient code. Understanding these concepts will help you write better Java applications.