Enhancements to pattern matching for switch in Java 20

24 Oct 2023

With the release of Java 20, several enhancements have been made to pattern matching for switch statements. Pattern matching was introduced in Java 14, allowing developers to write more concise and expressive code when working with switch statements. In Java 20, these enhancements take pattern matching to the next level, making it even more powerful and flexible.

Simplified syntax for type patterns

One of the key enhancements in Java 20 is the simplified syntax for type patterns in switch statements. Previously, when using pattern matching with instanceof, developers had to cast the matched object to a specific type. In Java 20, this casting is no longer necessary.

switch (obj) {
    case String s -> System.out.println("Found a string: " + s);
    case Integer i -> System.out.println("Found an integer: " + i);
    default -> System.out.println("Unknown type");
}

The new syntax allows for more concise and readable code, eliminating the need for explicit casting.

Improved handling of null values

Another enhancement in Java 20 is the improved handling of null values in pattern matching. In previous versions, pattern matching with null values required a separate case statement. In Java 20, null values can be handled directly within the case statement.

switch (obj) {
    case null -> System.out.println("Found a null value");
    case String s -> System.out.println("Found a string: " + s);
    case Integer i -> System.out.println("Found an integer: " + i);
    default -> System.out.println("Unknown type");
}

This improvement simplifies the code and makes it more intuitive to handle null values in switch statements.

Nesting patterns

Java 20 also introduces the ability to nest patterns within switch statements. This allows developers to match against multiple patterns and provides a more fine-grained control over the matching process.

switch (obj) {
    case String s && s.length() > 5 -> System.out.println("Found a long string: " + s);
    case String s && s.length() <= 5 -> System.out.println("Found a short string: " + s);
    case Integer i -> System.out.println("Found an integer: " + i);
    default -> System.out.println("Unknown type");
}

In the example above, the first case matches against a string that has a length greater than 5, the second case matches against a string with a length less than or equal to 5, and the third case matches against an integer. This nesting capability adds more flexibility and precision to pattern matching in switch statements.

Conclusion

The enhancements to pattern matching for switch statements in Java 20 provide developers with more powerful and flexible tools for writing concise and expressive code. The simplified syntax for type patterns, improved handling of null values, and nesting patterns make it easier to work with switch statements and handle different scenarios. These enhancements contribute to the overall improvement of the Java language and its capabilities for pattern matching.

References

#java #patternmatching