JAC444-Workshops 7 & 8 Solved

This assignment lets you practice functional programming as the new paradigm of programming added to Java 8. It includes concepts such as Generics, Functional Interfaces, Lambda Expressions, Method References, Streams, and Collections. 

 

Functional Programming allows you to write programs more concise, and in many cases (like working with collections), faster and with fewer bugs. Mostly, in Functional Programming, you specify what you want to do (not how you want it to be done, as it’s the case in non-functional programming paradigms.) Therefore, in this assignment, you should do all the tasks without using the traditional control statements (for, while, do/while, if/else, switch/case and even recursion) and just by using Functional Programming facilities provided in Java 8. 

(the only exception is inside the equals, constructor, and setter methods of class Student 

(discussed below); which you could use the if/else control structure!) 

 

Two basic elements of Functional Programming are Lambda Expressions (which are anonymous methods) and Method References, that have had them in the course (Week 7). Java 8 also introduces Streams (hint: don’t mix them up with IO Streams! They are new beasts!) Lambda Expressions and Streams let you do variety of tasks on the elements of a collection with great ease. 

 

In this assignment, you should first define a class Student which has four fields in this order: 

firstName as a String, lastName as a String, grade as a double, and department as a 

String. Provide one constructor for the class (which takes all the fields), setter and getter methods for all fields, a getName method which returns the full name of the student (ex. “John White”), toString, and equals methods. 

We assume that there has been a contest among students of different departments and the results have been gathered as grades. Therefore, in a second class, StudentProcess, you are supposed to use functional programming to do various tasks on a collection of Students. 

You might want to have a look at the following classes/interfaces, as you will need them while doing the assignment: 

•        java.util.Arrays; 

•        java.util.Comparator; 

•        java.util.List; 

•        java.util.Map; 

•        java.util.TreeMap; 

•        java.util.function.Consumer; 

•        java.util.function.BiConsumer; 

•        java.util.function.Function; 

•        java.util.function.Predicate; 

•        java.util.stream.Stream; 

•        java.util.stream.Collectors; 

•        java.util.Optional; 

 

Task 1: Create an array of Students in the beginning of your implementations, populate it with some Students, make a list out of your array, and print all its elements. You could create your own Student objects, hard-coded into your program and I will test your code run, against my input (use arbitrary values for first names, last names, grades – between 0.0 and 100.0 – and departments.) There is no need to read data from the file in this assignment (hint: have a look at List<E class and don’t forget to use method references to do this task and this assignment.) 

 

Task 2: Display Students with grades in the range 50.0-100.0, sorted into ascending order by grade. (hint: you need to return a Stream<Student out of your List<Student first, and then use Stream and Comparator classes’ methods classes’ methods.) 

Task 3: Display the first student in the collection with grade in the range 50.0-100.0 (hint: you need to return a Stream<Student out of your List<Student first, and then use Stream and Optional classes’ methods.) 

Task 4: Sort the Students (a)by their last names, and then their first names in ascending and (b)by their last names, and then their first names in descending orders and display the students after each of these two processes. (hint: you need to return a Stream<Student out of your List<Student first, and then use Stream and Comparator classes’ methods.) 

Task 5: Display unique Student last names, sorted. (hint: you need to return a Stream<Student out of your List<Student first, and map it to a Stream<String, and use its methods.) 

Task 6: Display Student full names, sorted in order by last name then first name. (hint: you need to return a Stream<Student out of your List<Student first, use Stream class’s methods, and map it to a Stream<String somewhere along the way.) 

Task 7: Display Students, grouped by their departments. (hint: you need to have an object of Map<String, List<Student and first populate it using Stream class’s methods, and second, display the desired output using Map class’s methods. You should also use Collectors for this task.) 

Task 8: Count and display the number of Students in each department. (hint: you need to have an object of Map<String, Long and first populate it using Stream class’s methods, and second, display the desired output using Map class’s methods. You should also use Collectors for this task.) 

Task 9: Calculate and display the sum of all Students’ grades. (hint: you need to return a Stream<Student out of your List<Student first, and then use Stream class’s methods to map it to a DoubleStream, and then, use DoubleStream methods to do the task.) 

 

Task 10: Calculate and display the average of all Students’ grades. (hint: you need to return a Stream<Student out of your List<Student first, and then use Stream class’s methods to map it to a DoubleStream, and then, use DoubleStream methods to do the task.) 

 

Typical Output:  

For a typical input such as: 

 Student[] students = { 

Student

Student

Student

Student

Student

Student

Student
         new ("Jack", "Smith", 50.0, "IT"),          new ("Aaron", "Johnson", 76.0, "IT"),          new ("Maaria", "White", 35.8, "Business"),          new ("John", "White", 47.0, "Media"),          new ("Laney", "White", 62.0, "IT"),          new ("Jack", "Jones", 32.9, "Business"),          new ("Wesley", "Jones", 42.89, "Media")}; 

 

The output could be: 

 

Task 1: 

 

Complete Student list: 

Jack     Smith       50.00   IT 

Aaron    Johnson     76.00   IT 

Maaria   White       35.80   Business 

John     White       47.00   Media 

Laney    White       62.00   IT 

Jack     Jones       32.90   Business 

Wesley   Jones       42.89   Media 

 

 

Task 2: 

 

Students who got 50.0-100.0 sorted by grade: 

Jack     Smith       50.00   IT 

Laney    White       62.00   IT 

Aaron    Johnson     76.00   IT 

 

 

Task 3: 

 

First Student who got 50.0-100.0: 

Jack     Smith       50.00   IT 

 

 

Task 4: 

 

Students in ascending order by last name then first: 

Aaron    Johnson     76.00   IT 

Jack     Jones       32.90   Business 

Wesley   Jones       42.89   Media Jack     Smith       50.00   IT 

John     White       47.00   Media 

Laney    White       62.00   IT 

Maaria   White       35.80   Business 

 

Students in descending order by last name then first: 

Maaria   White       35.80   Business 

Laney    White       62.00   IT 

John     White       47.00   Media Jack     Smith       50.00   IT 

Wesley   Jones       42.89   Media 

Jack     Jones       32.90   Business 

Aaron    Johnson     76.00   IT 

 

 Task 5: 

 

Unique Student last names: 

Johnson 

Jones 

Smith 

White 

 

 Task 6: 

 

Student names in order by last name then first name: 

Aaron Johnson 

Jack Jones 

Wesley Jones 

Jack Smith 

John White 

Laney White 

Maaria White 

 

 Task 7: 

 

Students by department: 

Media 

   John     White       47.00   Media 

   Wesley   Jones       42.89   Media 

IT 

   Jack     Smith       50.00   IT 

   Aaron    Johnson     76.00   IT 

   Laney    White       62.00   IT 

Business 

   Maaria   White       35.80   Business 

   Jack     Jones       32.90   Business 

 

 Task 8: 

 

Count of Students by department: 

Business has 2 Student(s) 

IT has 3 Student(s) 

Media has 2 Student(s) 

 

 Task 9: 

 

Sum of Students' grades: 346.59 

 

Task 10: 

Average of Students' grades: 49.51