java lambda expressions

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Java Lambda Expressions: A Comprehensive Tutorial

Lambda expressions, introduced in Java 8, revolutionized the way we write functional interfaces and streamlined event handling, collection processing, and more. They allow us to treat functionality as method arguments, or code as data, making our code more concise, readable, and maintainable. This tutorial will cover everything you need to know to effectively use lambda expressions in Java.

*1. What are Lambda Expressions?*

At their core, a lambda expression is an anonymous function – a function without a name. It can be passed around and executed. It's a way to represent a single method interface (functional interface) implementation in a much more compact and readable format. Think of it as a shorthand notation for creating instances of interfaces with a single abstract method.

*2. Functional Interfaces: The Foundation*

Lambda expressions are inextricably linked to functional interfaces*. A functional interface is an interface that has exactly *one abstract method (excluding methods inherited from `Object`). It can have default methods and static methods, but only one abstract method.

*Key characteristics of functional interfaces:*

*`@FunctionalInterface` Annotation:* Although not mandatory, it's strongly recommended to annotate functional interfaces with `@FunctionalInterface`. This annotation serves two purposes:
*Compiler Check:* The compiler will throw an error if you try to define a functional interface with more than one abstract method.
*Readability:* It clearly indicates your intent to use the interface as a functional interface.
*Single Abstract Method (SAM):* The interface must have only one abstract method. This is the method that the lambda expression will implement.

*Examples of Functional Interfaces:*

*`Runnable`:*



*`Comparator`:*



*`ActionListener` (from Swing):*



**Predefined Functional Interfaces in `java.util.function` ...

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