Implementing lambda expression using @FunctionInterface

Java 1.8 has formalized the lambda expression implementation through the use of the @FunctionalInterface annotation and the inclusion of the new specification on anonymous functions. This recipe will open a new technique in creating lambda expression.

Getting started

Using the same Eclipse project and EmployeeServiceImpl, add the needed service methods using @FunctionInterface components.

How to do it...

Many of the API classes in Java 1.8 use functional interfaces to simplify service implementation by applying the principles of functional programming. To illustrate what functional programming is, let us implement the following steps:

1. Create another version of the EmployeeRecord interface of the previous recipe that uses the @FunctionalInterface annotation:

@FunctionalInterface 
public interface EmployeeRecordService { 
  public List<Employee> getEmployees(); 
} 

2. Also in org.packt.function.codes.service, create a functional interface...