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Java Collection Programming Question

Posted by Admin on
Consider the four core interfaces, Set, List, Queue, and Map. For each of the following four     assignments, specify which of the four core interfaces is best-suited, and explain how to use it to implement the assignment.
1 :- Whimsical Toys Inc (WTI) needs to record the names of all its employees. Every month, an employee will be chosen at random from these records to receive a free toy.
2 :-  WTI has decided that each new product will be named after an employee but only first names will be used, and each name will be used only once. Prepare a list of unique first names.
3 :-  WTI decides that it only wants to use the most popular names for its toys. Count up the number of employees who have each first name.
4 :- WTI acquires season tickets for the local lacrosse team, to be shared by employees. Create a waiting list for this popular sport.   

Above question has been taken from Oracle website :
       

Below is the implentation of the question given above :
  
For Que 1 :
Function findRandomEmployee() is the implementation 

For Que 2 :
Function prepareUniqueListName() is the implementation

For Que 3 :
Function findpopularEmployeeName() is the implementation   

For Que 4 :
It is straight forward so did not implemented it .

Implementation :

import java.awt.List;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Random;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
      
class Employee
{
     public String firstname ;
     public String lastname ;
    
     Employee(String firstname , String lastname)
     {
        this.firstname = firstname;
        this.lastname = lastname;
     }
}


public class WhimsicalToysInc {
       public static void main(String[] args) {
              ArrayList<Employee> list = new ArrayList<Employee>();
              list.add(new Employee("ishant","gaurav"));
              list.add(new Employee("Ashish","Prasher"));
              list.add(new Employee("Hemant","Bisht"));
              list.add(new Employee("hemant","Bisht"));
              list.add(new Employee("Rahul","Rana"));
              list.add(new Employee("Deep","Money"));
             
             
              // Prining the random employee
              Employee e = findRandomEmployee(list);
              System.out.println("firstname "+e.firstname + " lastname "+e.lastname);
             
              // preparing the unique name list
              prepareUniqueListName(list);
             
              // finding the popular list of employees
              findpopularEmployeeName(list);
             
       }
      

       // function to find the popular Employee name
       private static void findpopularEmployeeName(ArrayList<Employee> list) {
      
              Map<String, Integer> frequency = new HashMap<String, Integer>();
              ArrayList<String> templist = new ArrayList<String>();
             
              for(Employee e : list)
              {
                     Employee temp = e;
                     templist.add(temp.firstname.toLowerCase());
              }
             
             
              for (String element : templist) {
                  if (frequency.containsKey(element)) {
                      frequency.put(element, frequency.get(element) + 1);
                  }
                  else {
                      frequency.put(element, 1);
                  }
              }
             
             
              for (Map.Entry<String, Integer> entry : frequency.entrySet()) {
                  System.out.print(entry.getKey() + " = " + entry.getValue() + " ");
              }
             
              System.out.println();
       }

      
    // Function to prepare the unique first name list of the employee
       private static void prepareUniqueListName(ArrayList<Employee> list) {
             
              // Customized Comparator to implement the ignore case unique element
              final Comparator<String> IGNORE_CASE = new Comparator<String>() {
                      public int compare(String s1, String s2) {
                          return s1.compareToIgnoreCase(s2);
                      }
                  };
        
              SortedSet<String>  uniquefirstname = new TreeSet<String>( IGNORE_CASE);
             
              for(Employee e : list)
              {
                     Employee temp = e;
                     uniquefirstname.add(temp.firstname);
              }
             
              System.out.println("Unique First Name : ");
             
              for( String s : uniquefirstname )
              {
                     System.out.println(s);
              }
             
    }
      
   
       //  Function to find the random employee from the list
       private static Employee findRandomEmployee(ArrayList<Employee> list) {
              int size = list.size();
              //System.out.println("size "+size);
              int rand = new Random().nextInt(size);
              //System.out.println(rand);
              Employee e =list.get(rand);
              return e;
       }
}

Please comment if you have any question or suggestion for the above code.


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