Java Functional Programming Example

This project demonstrates Functional Programming concepts in Java (Java 8+) using lambdas, method references, and the Streams API. It shows how to perform common operations on a list of employees, including filtering, sorting, mapping, reducing, and collecting data.

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Features

• Filter: Select employees based on department.
• Sort: Sort employees by salary.
• Map: Transform employee names to uppercase.
• Reduce: Calculate the total salary of all employees.
• Collect: Collect filtered employees into a new list.
• Method References: Simplify printing and functional operations.

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Code Explanation

1. Employees Class

   • Represents an employee with id, Name, department, and Salary.
   • Includes a constructor and a toString method for easy display.

2. Main Class (FunctionalProgramming)

   • Creates a list of employees.

   • Demonstrates the following:

   • Filtering:

     employees.stream()
              .filter(e -> e.department.equals("IT"))
              .forEach(System.out::println);

     Filters employees who work in the IT department.

   • Sorting:

     employees.stream()
              .sorted((e1, e2) -> Double.compare(e1.Salary, e2.Salary))
              .forEach(System.out::println);

     Sorts employees by salary in ascending order.

   • Mapping:

     employees.stream()
              .map(e -> e.Name.toUpperCase())
              .forEach(System.out::println);

     Converts employee names to uppercase.

   • Reducing:

     int totalSalary = employees.stream()
                                .map(e -> e.Salary)
                                .reduce(0, (a, b) -> a + b);

     Calculates the total salary of all employees.

   • Collecting:

     List<Employees> itEmployees = employees.stream()
                                            .filter(e -> e.department.equals("IT"))
                                            .collect(Collectors.toList());

     Collects IT employees into a new list.

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Learning Outcomes

• Understand how lambdas simplify code.
• Learn Streams API operations: filter, map, reduce, collect, sorted.
• See practical use of method references for cleaner code.
• Understand how functional programming concepts are applied in real-world backend and frontend applications.

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Real-World Relevance

• Frontend (JS/TS): Similar functional patterns are used in React/Angular for rendering and managing state.
• Backend (Java, Scala, Kotlin): Stream operations simplify processing of large datasets.
• Cloud & Big Data: Functional programming helps scale data pipelines efficiently.