Sealed classes—defined and implemented by JEP 409, as a standard language feature in Java 17—let you define hierarchies that accurately capture the knowledge of your business domain. By doing so, you can clearly define the code that handles the subclasses in a deliberate way, rather than defining generalized code that handles the unexpected classes in an unwanted manner.
In Mala Gupta’s article, you’ll learn what sealed classes are, why you need them, and how they will help improve your applications.
Take care, Alan Zeichick Editor in Chief, Java Magazine @zeichick
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The newest articles
Fight ambiguity and improve your code with Java 17’s sealed classes Declaring a class or interface as sealed enables you to control the classes or interfaces that can extend or implement it. As Mala Gupta explains, the goal of this language feature is to let you control the possible hierarchies in your business domain in a declarative manner. Read why this can be important.
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JUG spotlight: The Nederlandse Java User Group Participation in Java user groups (JUGs) can be extremely rewarding on both a personal and professional level. The Nederlandse Java User Group (NLJUG) has 5,000 members and offers regular meetings, a two-day developer conference, a quarterly magazine, and even the Masters of Java awards.
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