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Questions and Answers
What alternatives are there to inner classes?
What alternatives are there to inner classes?
Anonymous classes
What is an example of an anonymous class?
What is an example of an anonymous class?
A new class of Iterator with an implementation.
What are the key elements of anonymous classes?
What are the key elements of anonymous classes?
They are inner classes with no name and can be defined at the point of instantiation.
What are lambdas in Java?
What are lambdas in Java?
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Criteria for having lambdas include that you must implement an ______.
Criteria for having lambdas include that you must implement an ______.
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What is the syntax of lambda expressions?
What is the syntax of lambda expressions?
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What happens under the hood when we create a lambda?
What happens under the hood when we create a lambda?
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What is variable capture in lambdas?
What is variable capture in lambdas?
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Study Notes
Anonymous Classes
- Inner classes can be cumbersome when only used once; anonymous classes offer a solution by being unnamed inner classes.
- They simplify code structure by avoiding the need to define a separate class for single-use instances.
Iterator Interface Example
- Anonymous classes can be created on-the-fly to implement interfaces like Iterator.
- This demonstrates the convenience and flexibility of using anonymous classes.
Key Elements of Anonymous Classes
- Often used to instantiate an interface or extend a superclass without creating a separate named class.
- They provide a way to enhance existing code without cluttering the namespace.
Understanding Lambdas
- Lambdas are a concise syntax that simplify the creation of anonymous classes specifically for interfaces with one method.
- They improve readability and reduce boilerplate code in Java.
Criteria for Using Lambdas
- An interface must be implemented, specifically a functional interface with a single abstract method.
- Lambdas streamline method implementation, making it more efficient.
Lambda Expressions Syntax
- Lambda expressions utilize the
->operator, indicating the transition from parameters to the expression body. - The left side of
->contains parameters (optional brackets), while the right side contains the expression that yields the result. - Single-expression lambdas do not require explicit
returnstatements or curly braces.
Underlying Mechanism of Lambdas
- When a lambda is created, Java automatically generates a class that implements the specified interface.
- An instance of this class is created, and a reference to the object is provided, enabling its use.
Variable Capture in Lambdas
- Lambdas can capture final variables from their context, allowing them to access these external values.
- Non-final variables can also be captured, effectively creating a copy for use within the lambda.
- Lambdas can reference member variables directly through
this.
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Description
Explore the concepts of anonymous classes and lambdas in Java through interactive flashcards. This quiz will help you understand alternatives to inner classes and practical examples, including the usage of interfaces like Iterator.
