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Java Anonymous Classes

Anonymous Classes

Java anonymous classes implement interfaces inline.

What are Java Anonymous Classes?

Java anonymous classes are a type of inner class without a name. They are used to instantiate classes that may only need to be used once, particularly when implementing interfaces or extending classes. Anonymous classes are beneficial for creating concise and flexible code snippets, making them ideal for situations where a full class implementation is unnecessary.

Creating an Anonymous Class to Implement an Interface

In Java, you can create an anonymous class to implement an interface inline. This means you define the implementation of the interface methods directly where the instance of the class is created. It simplifies code when a class is only needed for a short time and does not need a specific name.

Using Anonymous Classes to Extend a Class

In addition to implementing interfaces, anonymous classes can also extend existing classes. This is useful when you want to override certain methods of the parent class for a one-time use.

When to Use Anonymous Classes

Anonymous classes are best used when:

  • You need to implement methods of an interface or override methods of a class for a one-time use.
  • The class is small and only used in a limited scope.
  • You want to avoid creating a separate named class file.

However, avoid using anonymous classes when:

  • The class requires multiple methods or fields, making it too complex.
  • The class needs to be reused elsewhere in your code.

Limitations of Anonymous Classes

While anonymous classes provide a concise way to implement interfaces or extend classes, they do have limitations:

  • They cannot have explicit constructors since they do not have a name.
  • They are limited to one-time use within the scope of their creation.
  • They can make code harder to read if overused, as they increase complexity in understanding the flow of the program.

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