How is lambda expression used in Java?

Lambda expressions are a new feature introduced in Java 8 that simplifies the way functional interfaces are implemented. Essentially, they are anonymous functions that can be used to replace certain instances where anonymous inner classes are used, making the code more concise and readable.

The syntax of a Lambda expression is as follows:

(parameters) -> expression
或
(parameters) -> { statements; }

Among them, parameters are the method parameters, expression is a single statement, and statements are a series of statements.

Lambda expressions can be applied to functional interfaces, which are interfaces containing only one abstract method. Through lambda expressions, it is possible to implement the methods of functional interfaces in a more concise way in the code. Lambda expressions can be passed as parameters to methods, passed to callers of methods, and executed when needed.

The use of lambda expressions can greatly simplify code, improve its readability and maintainability. Lambda expressions are widely used in Java for concurrency programming, collection operations, event handling, and more.