This article explores how you can improve your Java Code quality using Pattern Matching and Sealed Classes. Java Pattern Matching allows you to write more concise and readable code when working with complex data structures. It simplifies extracting data from data structures and performing operations on them. Let's dive in and learn more about pattern matching and sealed classes.Pattern Matching matches a value against a pattern that includes variables and conditions. If the value matches the pattern, the corresponding parts of the value are bound to the variables in the pattern. This allows for more readable and intuitive code. There are two types of pattern matching: traditional and modern. Let's see the differences between the two in the following sections.In traditional pattern matching, the switch statement is extended to support pattern matching by adding the case keyword with a pattern argument. The switch statement can match against a primitive type, wrappers, enums, and strings.For example:The Java method printGreetingBasedOnInput takes an input string and prints a corresponding greeting message based on its value using a switch-case statement. It covers cases for "hello," "goodbye," and "thank you," providing appropriate responses, and defaults to "I don't understand" for any other inputs.In modern pattern matching, the switch statement can match against a variety of patterns like any type of objects, enums, or primitives. The case keyword is used to specify the pattern to match against.This code snippet uses a more concise syntax. It simplifies the code by directly specifying the action to perform for each case label. Before Java 16, we needed to check the object's type and then explicitly cast it to a variable. The enhanced instanceof operator introduced in Java 16 can both verify the type and perform an implicit cast to a variable, like in the example below: The enhancement of instanceof becomes particularly valuable when working with pattern guards. Pattern guards are a way to make case statements in Java pattern matching more specific by including boolean expressions. This allows for more fine-grained control over how patterns are matched and can make code more readable and expressive.Based on the examples shown above, you can hopefully see that Java pattern matching offers various benefits:Sealed classes allow developers to restrict the set of classes that can extend or implement a given class or interface. Sealed classes provide a way to create a hierarchy of classes or interfaces that can be extended or implemented by only a specified set of classes.For example:In this example, we've defined a sealed class called Result which can be extended by either Success or Failure classes. Any other class that attempts to extend Result will result in a compilation error.This provides a way to restrict the set of classes that can be used to extend Result, making the code more maintainable and extensible.You can use sealed classes and their permitted subclasses in switch statements with pattern matching. This can make the code more concise and easier to read. Here's an example:In the case of sealed classes, the compiler requires a default branch in pattern matching to ensure that all possible cases are covered. Since sealed classes have a fixed set of permitted subclasses, it is possible to cover all cases with a finite number of case statements.If a default branch is not included, it's possible to add a new subclass to the hierarchy in the future, which would not be covered by the existing case statements. This would result in a runtime error, which could be difficult to debug.By requiring a default branch, the compiler ensures that the code is complete and covers all possible cases, even if new subclasses are added to the sealed class hierarchy in the future. This helps to prevent runtime errors and makes the code more robust and maintainable. If we modify the Result class to include a new subclass called Pending and we have not included that in our pattern matching, it will be covered by the default branch.When working with a Sealed Interface in Java, the compiler will not require a default branch in pattern matching if all cases are covered.In case a branch is missing, the compiler will require a default branch to ensure that all possible cases are handled. We are always required to include the default branch when working with Sealed Classes. Here's a code example:Here are some key takeaways of using Pattern Matching and Sealed Classes in Java code:Thank you so much for reading.Engineer If you read this far, thank the author to show them you care. Say Thanks Learn to code for free. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Get started freeCodeCamp is a donor-supported tax-exempt 501(c)(3) charity organization (United States Federal Tax Identification Number: 82-0779546)Our mission: to help people learn to code for free. We accomplish this by creating thousands of videos, articles, and interactive coding lessons - all freely available to the public. We also have thousands of freeCodeCamp study groups around the world.Donations to freeCodeCamp go toward our education initiatives, and help pay for servers, services, and staff. You can make a tax-deductible donation here.