Question

Must be using Java Eclipse Please

4. Test program LinkedList.java, and make sure that you understand each operation in the
program. (refer to linkedListApplication.java)

6. (Programming) Use LinkedList as a reference, add the following operations in the class
LinkedList;
a) Find the average data values of the linked list.
b) Find the node with largest key, and then delete the node. (Note, you must return
the node, not just the largest key)
c) Test ALL operations (Search, Insert, Delete, Append/Remove to/from the header)
in the Main method. (Also display the average of the data values of the linked list,
the largest key, the linked list before and after deleting the node with the largest
key;

7. (Programming) Modify LinkedList.java programs so that it handles employee objects.
Make your program menu-driven.
a) Find the average salary of the employees in the linked list.
b) Find the employee with largest ID, and then delete the node. (Note, you must return
the employee, not just the largest key, and delete it)
c) Test ALL operations (Search, Insert, Delete, Append/Remove to/from the header) in
the Main method. (Also display the average salary, the employee with largest ID, the
linked list before and after deleting the employee with the largest key;

LinkedList.java

import java.util.*;

public class LinkedList
{
   public Node header;

   public LinkedList()
   {
       header = null;
   }

   public final Node Search(int key)
   {
       Node current = header;
       while (current != null && current.item != key)
       {
           current = current.link;
       }
       return current;
   }

   public final void Append(int newItem)
   {
       Node newNode = new Node(newItem);
       newNode.link = header;
       header = newNode;
   }

   public final Node Remove()
   {
       Node x = header;
       if (header != null)
       {
           header = header.link;
       }
       return x;
   }

   public final Node searchPrevious(int key)
   {
       if (header == null)
       {
           return header;
       }
       else
       {
           Node current = header;
           while (!(current.link == null) && (current.link.item != key))
           {
               current = current.link;
           }
           return current;
       }
   }

   public final void Insert(int newItem, int preKey)
   {
       Node current;
       Node newNode = new Node(newItem);
       current = Search(preKey);
       if (current == null)
       {
           System.out.println("there is no such preKey!");
       }
       else
       {
           newNode.link = current.link;
           current.link = newNode;
       }
   }

   public final void Delete(int key)
   {
       if (header == null) // The list is empty!
       {
           System.out.println("The list is empty!");
       }
       else
       {
           if (header.item == key) // header to be deleted.
           {
               header = header.link;
           }
           else
           {
               Node p = searchPrevious(key);
               if (p.link == null)
               {
                   System.out.println("There is no such item!");
               }
               else
               {
                   p.link = p.link.link;
               }
           }
       }
   }

public final void ShowLinkedList()
{
if (header == null)
   System.out.println("The list is empty!");
else
{
Node current = header;
System.out.printf("%1$s->", current.item);
while (!(current.link == null))
{
current = current.link;
System.out.printf("%1$s->", current.item);

}
System.out.printf("null");
System.out.println();
}
}
   public final void PrintList()
   {
       if (header == null)
       {
           System.out.println("The list is empty!");
       }
       else
       {
           Node current = header;
           System.out.println(current.item);
           while (!(current.link == null))
           {
               current = current.link;
               System.out.println(current.item);
           }
       }
   }
}

Answer 1

//----------- LinkedList.java -------

import java.util.*;

class Node {
   public int item;
   public Node link;

   Node(int num) {
       item = num;
       link = null;
   }
}

public class LinkedList {
   public Node header;

   public LinkedList() {
       header = null;
   }

   public final Node Search(int key) {
       Node current = header;
       while (current != null && current.item != key) {
           current = current.link;
       }
       return current;
   }

   public final void Append(int newItem) {
       Node newNode = new Node(newItem);
       newNode.link = header;
       header = newNode;
   }

   public final Node Remove() {
       Node x = header;
       if (header != null) {
           header = header.link;
       }
       return x;
   }

   public final Node searchPrevious(int key) {
       if (header == null) {
           return header;
       } else {
           Node current = header;
           while (!(current.link == null) && (current.link.item != key)) {
               current = current.link;
           }
           return current;
       }
   }

   public final void Insert(int newItem, int preKey) {
       Node current;
       Node newNode = new Node(newItem);
       current = Search(preKey);
       if (current == null) {
           System.out.println("there is no such preKey!");
       } else {
           newNode.link = current.link;
           current.link = newNode;
       }
   }

   public final void Delete(int key) {
       if (header == null) // The list is empty!
       {
           System.out.println("The list is empty!");
       } else {
           if (header.item == key) // header to be deleted.
           {
               header = header.link;
           } else {
               Node p = searchPrevious(key);
               if (p.link == null) {
                   System.out.println("There is no such item!");
               } else {
                   p.link = p.link.link;
               }
           }
       }
   }

   public final void ShowLinkedList() {
       if (header == null)
           System.out.println("The list is empty!");
       else {
           Node current = header;
           System.out.printf("%1$s->", current.item);
           while (!(current.link == null)) {
               current = current.link;
               System.out.printf("%1$s->", current.item);

           }
           System.out.printf("null");
           System.out.println();
       }
   }

   public final void PrintList() {
       if (header == null) {
           System.out.println("The list is empty!");
       } else {
           Node current = header;
           System.out.println(current.item);
           while (!(current.link == null)) {
               current = current.link;
               System.out.println(current.item);
           }
       }
   }
   //method getAverage() that returns the average of Node values
   //in linked list.
  
   public double getAverage()
   {
       //if header is null then average will be 0.
       if(header == null)
       {
           return 0;
       }
       //to store average and sum of node values
       double avg = 0.0;
       double sum = 0;
       //store header in current node.
       Node current = header;
       //count is the number of nodes in linked list.
       int count = 0;
       //till last node.
       while (current != null)
       {
           //add current node value to the sum variable
           sum += current.item;
           //move to next node.
           current = current.link;
           //increment the count of nodes.
           count++;
       }
       //average is the division of sum / number of nodes.
       avg = sum / count;
       //return the average.
       return avg;
   }
   //function that returns the largest Node in the list.
   public Node getLargestNode()
   {
       //if header is null then there is no Largest Node.
       if(header == null)
       {
           return null;
       }
      
       //to store current node while processing.
       Node current = header;
       //set largest node value of item as the header node value.
       Node largest = new Node(current.item);
       //till end of last node.
       while (current!=null)
       {
           //if current node value is greater than the largest item value.
           if(current.item > largest.item)
           {
               //then largest item value will be current node value.
               largest.item = current.item;
           }
           //move to next node.
           current = current.link;
       }
       //return the largest node.
       return largest;
   }
}

//-------- linkedListApplication.java ------
//class that tests all the functionalities of LinkedList class.
public class linkedListApplication {
   public static void main(String[] args)
   {
       //crate linked list object
       LinkedList list = new LinkedList();
       //add values using Append() method
       list.Append(5);
       list.Append(1);
       list.Append(2);
       list.Append(3);
       list.Append(4);
       //display linked list.
       System.out.println("\nLinked List After insertion using Append()-----");
       list.ShowLinkedList();
      
       //insert using Insert(10,3) which inserts 10 after key 3.
       System.out.println("\nInserting 10 at previous key 3 using Insert() method");
       list.Insert(10,3);
       System.out.println("\nLinked List After insertion using Insert()-----");
       list.ShowLinkedList();
      
       //call getAverage() and store the result
       double avg = list.getAverage();
       System.out.println(String.format("\nAverage of Linked List values using getAverage() method : %.2f",avg));
      
      
       //call getLargestNode() and store the result
       Node largest = list.getLargestNode();
       System.out.println("\nLargest value in Linked list: "+largest.item);
      
       System.out.println("\nLinked List before deleting largest node: "+largest.item);
       list.PrintList();
      
       //remove the largest item value in linked list.
       list.Delete(largest.item);
       System.out.println("\nLinked List After Deleting Largest Node Value using Delete() method: "+largest.item+" -----");
       list.ShowLinkedList();
      
       System.out.println("\nLinked List before performing Remove() method");
       list.ShowLinkedList();
      
       //call Remove() method to remove head from linked list.
       list.Remove();
       System.out.println("\nLinked List After performing Remove() method");
       list.ShowLinkedList();
   }

}

//---------- OUTPUT -------------

// ----------------------- PART 7 ---------------------------

//----------- LinkedList.java -------

import java.util.*;

class Employee {
   public String name;
   public int id;
   public double salary;
   public Employee link;

   Employee(String name,int id,double salary) {
       this.name =name;
       this.id = id;
       this.salary = salary;
       link = null;
   }

   @Override
   public String toString() {
       return "Employee [ name=" + name + " , id=" + id + " , salary=" + salary + " ]";
   }
  
}

public class LinkedList {
   public Employee header;

   public LinkedList() {
       header = null;
   }

   public final Employee Search(int key) {
       Employee current = header;
       while (current != null && current.id != key) {
           current = current.link;
       }
       return current;
   }

   public final void Append(String name,int id,double salary) {
       Employee newEmployee = new Employee(name,id,salary);
       if(Search(newEmployee.id) == null)
       {
           newEmployee.link = header;
           header = newEmployee;
       }
       else
       {
           System.out.println("\nDuplicate User.User with id: "+id+" is already Existed");
       }
      
   }

   public final Employee Remove() {
       Employee x = header;
       if (header != null) {
           header = header.link;
       }
       return x;
   }

   public final Employee searchPrevious(int key) {
       if (header == null) {
           return header;
       } else {
           Employee current = header;
           while (!(current.link == null) && (current.link.id != key)) {
               current = current.link;
           }
           return current;
       }
   }

   public final void Insert(String name,int id,double salary, int preKey) {
       Employee current;
       Employee newEmployee = new Employee(name,id,salary);
       current = Search(preKey);
       if (current == null) {
           System.out.println("there is no such preKey!");
       } else {
           if(Search(id) == null)
           {
               newEmployee.link = current.link;
               current.link = newEmployee;
           }
           else
           {
               System.out.println("\nDuplicate User.User with id: "+id+" is already Existed");
           }
       }
   }

   public final void Delete(int key) {
       if (header == null) // The list is empty!
       {
           System.out.println("The list is empty!");
       } else {
           if (header.id == key) // header to be deleted.
           {
               header = header.link;
           } else {
               Employee p = searchPrevious(key);
               if (p.link == null) {
                   System.out.println("There is no such item!");
               } else {
                   p.link = p.link.link;
               }
           }
       }
   }

   public final void ShowLinkedList() {
       if (header == null)
           System.out.println("The list is empty!");
       else {
           Employee current = header;
           System.out.printf("[ %s,%d ] -> ", current.name, current.id);
           while (!(current.link == null)) {
               current = current.link;
               System.out.printf("[ %s,%d ] -> ", current.name, current.id);

           }
           System.out.printf("null");
           System.out.println();
       }
   }

   public final void PrintList() {
       if (header == null) {
           System.out.println("The list is empty!");
       } else {
           Employee current = header;
           System.out.println(current);
           while (!(current.link == null)) {
               current = current.link;
               System.out.println(current);
           }
       }
   }
   //method getAverage() that returns the average of Employee Salary values
   //in linked list.
  
   public double getAverageSalary()
   {
       //if header is null then average will be 0.
       if(header == null)
       {
           return 0;
       }
       //to store average and sum of employee salary
       double avg = 0.0;
       double sum = 0;
       //store header in current node.
       Employee current = header;
       //count is the number of nodes in linked list.
       int count = 0;
       //till last node.
       while (current != null)
       {
           //add current node salary value to the sum variable
           sum += current.salary;
           //move to next node.
           current = current.link;
           //increment the count of nodes.
           count++;
       }
       //average is the division of sum / number of nodes.
       avg = sum / count;
       //return the average.
       return avg;
   }
   //function that returns the largest Employee in the list.
   public Employee getLargestEmployeeId()
   {
       //if header is null then there is no Largest Employee.
       if(header == null)
       {
           return null;
       }
      
       //to store current node while processing.
       Employee current = header;
       //set largest node value of item as the header node value.
       Employee largest = new Employee(current.name,current.id,current.salary);
       //till end of last node.
       while (current!=null)
       {
           //if current node value is greater than the largest item value.
           if(current.id > largest.id)
           {
               //then largest item value will be current node value.
               largest.id = current.id;
               largest.name = current.name;
               largest.salary = current.salary;
           }
           //move to next node.
           current = current.link;
       }
       //return the largest node.
       return largest;
   }
}

//-------- linkedListApplication.java ------
//class that tests all the functionalities of LinkedList class.
public class linkedListApplication {
   public static void main(String[] args)
   {
       //crate linked list object
       LinkedList list = new LinkedList();
       //add values using Append() method
       list.Append("John wick",1,3000);
       list.Append("Tony Stark",2,40000);
       list.Append("Barry Allen",2,20000);
       list.Append("Rambo",3,40000);
       //display linked list.
       System.out.println("\nEmployees List After insertion using Append()-----");
       list.ShowLinkedList();
      
       //insert using Insert() which inserts Barray Allen with id 4.
       System.out.println("\nInserting Barry Allen with id 4 at previous key 3 using Insert() method");
       list.Insert("Barry Allen",4,25000,3);
       System.out.println("\nEmployees List After insertion using Insert()-----");
       list.ShowLinkedList();
      
       //call getAverage() and store the result
       double avg = list.getAverageSalary();
       System.out.println(String.format("\nAverage Salary of Employees List values using getAverage() method : %.2f",avg));
      
      
       //call getLargestNode() and store the result
       Employee largest = list.getLargestEmployeeId();
       System.out.println("\nLargest Id in Linked list: "+largest.id);
       System.out.println("Employee Details: "+largest);
      
       System.out.println("\nEmployees List before deleting largest node with id: "+largest.id);
       list.ShowLinkedList();
      
       //remove the largest item value in linked list.
       list.Delete(largest.id);
       System.out.println("\nEmployees List After Deleting Largest Node with Id Value using Delete() method: "+largest.id+" -----");
       list.ShowLinkedList();
      
       System.out.println("\nEmployees List before performing Remove() method");
       list.ShowLinkedList();
      
       //call Remove() method to remove head from linked list.
       list.Remove();
       System.out.println("\nEmployees List After performing Remove() method");
       list.PrintList();
   }

}

//-------------- OUTPUT ----------------