Abstract Cart class

import java.util.ArrayList;
import java.util.HashMap;
/**
* The Abstract Cart class represents a user's cart. Items of Type T can be added
* or removed from the cart. A hashmap is used to keep track of the number of items
* that have been added to the cart example 2 apples or 4 shirts.
* @author Your friendly CS Profs
* @param -Type of items that will be placed in the Cart.
*/
public abstract class AbstractCart {

   protected HashMap cart;
  
   public AbstractCart() {
       this.cart = new HashMap();
   }
  
   /**
   * Calculates the total value of items in the cart.
   * @return total (double)
   */
   public abstract double calculateTotal();
  
   /**
   * Add an item of type T to the Cart (HashMap: The product is the key
   * and the value is the count).
   * If product doesn't exist in the cart add it and set count to one.
   * Otherwise increment the value.
   * @param item
   * @return boolean
   */
   public void addItem(T item) {
//fill in
   }
  
   /**
   * Adds every item in the Arraylist of Type T or any subclass of T.
   * @param items: An array of items
   * @return true if items have been currently added.
   */
   public void addItems(ArrayList items) {
         
   }
  
   /**
   * Removes an item of type T from the list.
   * If the only one item, we remove that item.
   * If item count is greater than one decrement the count.
   * If you are able to remove the item then return true.
   * If the item doesn't exist return false.
   * @param item
   * @return true
   * in the list.
   */
   public boolean removeItem(T item) {
   //fill in
       return true;
   }
  
  
   /**
   * Removes all of the item of items of Type T or any subclass of T from the cart.
   * @param item
   * @return true if items have been successfully remove.
   */
   public void removeItems(ArrayList items) {
       //fill in
   }
  
   /**
   * Check to see if the cart contains an item.
   * @param item
   * @return true if cart contains the item. Returns False otherwize
   */
   public boolean contains(T item) {
       return cart.containsKey(item);
   }
  

  
}

AmazonCart

public class AmazonCart extends AbstractCart {

   @Override
   /**
   * Calculate the total of all the items in the cart include tax.
   * @return total
   */

   public double calculateTotal() {
       double total = 0.0;
       for(AmazonProduct item : this.cart.keySet()) {
           int itemCount = this.cart.get(item);
           total += (item.getPrice() + item.calcTax())*itemCount;
       }
       return total;
   }

}

AmazonCartTest

import static org.junit.Assert.*;

import java.util.ArrayList;

import org.junit.Test;

public class AmazonCartTest {

   @Test
   public void testAddingItemToCard() {
       Milk m = new Milk(2.5, "Lactose Free", false);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItem(m);
       if(amazonCart.contains(m) != true) {
           fail("Error AmazonCart-Line-13: Items not currently added to cart");
       }
   }
  
   @Test
   public void testCalculateTotal() {
       Milk m = new Milk(3, "Lactose Free", true);
       DVD d = new DVD(10, "Black Panther", true);
       Shirt s = new Shirt(100, "Versace", false);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItem(m);
       amazonCart.addItem(d);
       amazonCart.addItem(s);
       assert(amazonCart.calculateTotal() == 120.33);  
   }
  
   @Test
   public void testAddingDupplicates() {
       Milk m = new Milk(3, "Lactose Free", true);
       DVD d = new DVD(10, "Black Panther", true);
       Shirt s = new Shirt(100, "Versace", false);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItem(m);
       amazonCart.addItem(m);
       amazonCart.addItem(d);
       amazonCart.addItem(d);
       amazonCart.addItem(s);
       amazonCart.addItem(s);
       assert(amazonCart.calculateTotal() == 240.66);  
   }
  
   @Test
   public void testRemovingItem() {
       Milk m = new Milk(3, "Lactose Free", true);
       DVD d = new DVD(10, "Black Panther", true);
       Shirt s = new Shirt(100, "Versace", false);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItem(m);
       amazonCart.removeItem(m);
       amazonCart.addItem(d);
       amazonCart.addItem(s);
       amazonCart.addItem(s);
       assert(amazonCart.calculateTotal() == 224.3);  
   }
  
   @Test
   public void testRemovingItem2() {
       Milk m = new Milk(3, "Lactose Free", true);
       DVD d = new DVD(10, "Black Panther", true);
       Shirt s = new Shirt(100, "Versace", false);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItem(m);
       amazonCart.removeItem(m);
       assert(amazonCart.removeItem(d) == false);
       amazonCart.addItem(d);
       amazonCart.addItem(s);
       amazonCart.addItem(s);
       assert(amazonCart.calculateTotal() == 224.3);  
   }
  
   @Test
   public void testRemovingItem3() {
       Milk m = new Milk(3, "Lactose Free", true);
       DVD d = new DVD(10, "Black Panther", true);
       Shirt s = new Shirt(100, "Versace", false);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItem(m);
       amazonCart.addItem(m);
       amazonCart.removeItem(m);
       amazonCart.removeItem(m);
       assert(amazonCart.removeItem(d) == false);
       amazonCart.addItem(d);
       amazonCart.addItem(s);
       amazonCart.addItem(s);
       assert(amazonCart.calculateTotal() == 224.3);  
   }
  
  
   @Test
   public void testAddingArrayListOfItems() {
       ArrayList mArray = new ArrayList<>();
       Milk m1 = new Milk(3, "Lactose Free", true);
       Milk m2 = new Milk(2, "Whole Milk", true);
       Milk m3 = new Milk(9.5, "Goats Milk", true);
       mArray.add(m1);
       mArray.add(m2);
       mArray.add(m3);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItems(mArray);
   }

  
   @Test
   public void testRemovingArrayListOfItems() {
       ArrayList mArray = new ArrayList<>();
       Milk m1 = new Milk(3, "Lactose Free", true);
       Milk m2 = new Milk(2, "Whole Milk", true);
       Milk m3 = new Milk(9.5, "Goats Milk", true);
       mArray.add(m1);
       mArray.add(m2);
       mArray.add(m3);
       AmazonCart amazonCart = new AmazonCart();
       amazonCart.addItems(mArray);
       amazonCart.removeItems(mArray);
       assert(amazonCart.calculateTotal() == 0);
   }
}

Java assignment, abstract class, inheritance, and polymorphism.

these are the following following classes:

Animal (abstract)

• Has a name property (string)
• Has a speech property (string)
• Has a constructor that takes two arguments, the name and the speech
• It has getSpeech() and setSpeech(speech)
• It has getName and setName(name)
• It has a method speak() that prints the name of the animal and the speech.

o Example output: Tom says meow.

Mouse

• Inherits the Animal class
• Has a constructor takes a name and also pass “squeak” as speech to the super class
• Has a method chew that takes a string presenting the name of a food.

o Example output: Jerry is chewing on cheese.

Cat

• Inherits the Animal class
• Has a constructor takes a name and also pass “meow” to the super class ^•
• Has a method chase that takes a Mouse object.  

o Example output: Tom is chasing Jerry.

TomAndJerry

• Has a static method makeAnimalSpeak that takes an Animal object and makes it animal speak.
• Has a main method that
  • Create a variable of Animal type and assign it a mouse named “Jerry”
  • Create a variable of Animal type and assign it a cat named “Tom”
  • all the method makeAnimalSpeak on the animals you have created
  • Make the mouse chew on “cheese”
  • Make the cat chase the mouse

Sample run:

Jerry says squeak.

Tom says meow.

Jerry is chewing on cheese.

Tom is chasing Jerry.

Please describe this( Encryption technique -abstract and introduction) below Research paper in your Word

​Abstract

In network communication system, exchange of data mostly occurs on networked computers and devices, mobile phones and other internet based smart electronic gadgets. Importance of network security is increasing day by day for various network and software applications in human life. Many of the human activities are automatic and in future more areas will come as part of networking system. So most of the end-devices will come to the internet and connect, it is important to ensure the security of data being transmitted. The data and network encryption algorithms play a huge role to ensure the security of data in transmission. In this paper, we provide a theoretical overview of various encryption techniques, namely those that range from changes in the position of a letter or word to word transformations and transposition. These not only provide security when sending messages, but also security for passwords that are used to decipher and to encrypt. The conclusions in this study examine the current theoretical framework,
and propose the usage of methods to prevent online security breaches

​ Introduction
Encryption simply means the translation of data blocks into a secret code which is considered the most effective way to ensure data security. To read a secret file one must have access to a secret key that enables to decrypt it. Unsecured data where no encryption algorithms were used travels through different networks are open to many types of attacks and can be read, changed or forged by any attacker who has access to that data or network. To prevent such attacks encryption and decryption techniques are employed. Encryption algorithms are used by many software and network applications, but most of them are not free from cyber-attacks. Now a days encryption techniques uses algorithms with a “key” to encrypt data into digital secret code and then decrypting it by restoring it to its original data. It is important to protect things like biometric information, email data, medical records, corporate information, personal data, legal documents, transactions details from unauthorized access. Encryption techniques uses a fixed length parameter or key for data transformation. There are mainly two types of algorithms used to encrypt data, asymmetric encryption and symmetric encryption. Many research and analysis of different encryption algorithms such as DES, 3DES, AES, Blowfish, Twofish, Serpent, RC2, RC5, are going on which helps to identify the pros and cons of algorithms in various platforms and application areas. Today's most widely used encryption algorithms fall into two categories: symmetric and asymmetric. Symmetric-key ciphers, also referred to as "secret key," use a single key, sometimes referred to as a shared secret because the system doing the encryption must share it with any entity it intends to be able to decrypt the encrypted data. The most widely used symmetric-key cipher is the ​Advanced Encryption Standard (AES​), which was designed to protect government classified information.
Symmetric-key ​encryption is usually much faster than asymmetric encryption, but the sender must exchange the key used to encrypt the data with the recipient before the recipient can perform decryption on the cipher text. The need to securely distribute and manage large numbers of keys means most cryptographic processes use a symmetric algorithm to efficiently encrypt data, but they use an asymmetric algorithm to securely exchange the secret key. All securely transmitted live traffic today is encrypted using symmetric encryption algorithms for example such as live telephone conversation, streaming video transmission, high speed data link. Blowfish, AES, RC4,DES, RC5, and RC6 are examples of symmetric encryption. The most widely used symmetric algorithm is AES-128, AES-192, and AES-256. In asymmetric​ key encryption, different keys are used for encrypting and decrypting a message. Asymmetric cryptography, also known as public key cryptography, uses two different but mathematically linked keys, one public and one private. The public key can be shared with everyone, whereas the private key must be kept secret. The RSA encryption algorithm is the most widely used public key algorithm, partly because both the public and the private keys can encrypt a message; the opposite key from the one used to encrypt a message is used to decrypt it. This Attribute provides a method of assuring not only confidentiality, but also the integrity, authenticity and non reputability of electronic communications and data at rest through the use of digital signatures. Diffie-Hellman, RSA, ECC, ElGamal, DSA. The following are the major asymmetric encryption algorithms used for encrypting or digitally signing data.

It is required to develop an application in Java to perform some operations of a bank. The application will have the following classes:

1. Class called Person having following data fields (private):

firstName (String), lastName(String), gender(char), cpr(long), mobile(String) and following methods:

1. Constructor having 5 parameters to initialize all data fields,
2. Set and get methods for all data fields,
3. toString method to return String equivalent of all data fields,

2. Abstract class called Account having following data fields(protected):

accountHolder(Person), ccountNum(long), balance(double)and following methods:

1. Constructor having 3 parameters for all 3 data fields including an object of type Person.
2. Get methods for all three data fields.
3. Abstract method updateBalance to update balance according to parameter.
4. Abstract method withdraw to withdraw money from the account and update balance.
5. Abstract method deposit to deposit money in the account and update balance.
6. method to return String equivalent of all data fields by calling toString method of class Person.

3. Class called Savingsccount that inherit the properties of abstract class Account having following additional data field:

interestRate(double) and following methods:

1. Constructor having 4 parameters for all data fields including that of class Account.
2. Set and get methods for interestRate.
3. Implementation of method updateBalance.
4. Implementation of method withdraw.
5. Implementation of method deposit.
6. Overloaded toString method to return String equivalent of all data fields.

4. Write a class called Bank having only main method to test all functionalities of the application.

Question: If a hospital would like to select a good nurse, what would be the types of selection tests needed to choose the candidates: a) Mention the names of only two tests and then b) Mention one reason for choosing each of them; Also what are the types of questions that they may be asked in the interview: c) Give examples of four different types of interview questions (write examples of these sentences). d) Mention one type of interview the hospital should administer in order to interview a large number of nurses quickly

1. Mention and briefly explain the advantages and disadvantages of using statistical sampling in a financial statement audit.

2. Mention and briefly explain at what stage or stage of an audit of financial statements the use of statistical sampling could be considered.

a.) Describe the structure of the GroEL/GroES complex, make sure to mention domains but no need to mention secondary structures involved in the domains (1 pt)

b.) Describe the roles of ATP binding and ATP hydrolysis in GroEL/GroES function.

please write an abstract of the topic "The principles of construction and use of econometric models and methods in economic research"