Lambda Expression

A lambda expression is a short block of code that represents a function. It can be used to create anonymous functions that can be passed as arguments to methods or stored in variables.

In Java, lambda expressions are used to implement functional interfaces, which are interfaces with only one abstract method. Here's an example of how you can use a lambda expression to implement a functional interface: 

@FunctionalInterface
public interface MyFunctionalInterface {
    void doSomething();
}

// Implementation using a lambda expression
MyFunctionalInterface myFunction = () -> {
    // code goes here
};

In this example, the MyFunctionalInterface interface is a functional interface because it has only one abstract method. The lambda expression () -> { /* code goes here */ } is used to implement this interface. The lambda expression takes no arguments (as indicated by the empty parentheses) and consists of a block of code (indicated by the curly braces).

Lambda expressions can be used in any context where a function is expected. They can be passed as arguments to methods, stored in variables, and so on. They are often used in conjunction with the Java Streams API to perform functional-style operations on streams of data.