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Does this contain Polymorphic references? If not, how could it be implemented?

I am not too familiar with polymorphism, and was wondering if I have it used in my code?
If this doesn't contain a polymorphic reference, could you lead me in a direction of where I would need to go? The files that the program is using are not included, as I am mainly curious about whether or not any polymorphic references are used.
java file 1 - this file runs the program
import java.util.Scanner;
public class ADTDemo {
ADTDictionary dictionary;
public static void menu() {
System.out.println("Welcome the Faculty Directory Program");
System.out.println(" Use commands:");
System.out.println(" list all");
System.out.println(" list DEPT_NAME");
System.out.println(" add DEPT_NAME, FIRST LAST");
System.out.println(" remove DEPT_NAME, FIRST LAST");
System.out.println(" exit");
}
public static void main(String[] args) {
menu();
String command;
ADTDemo dictObj = new ADTDemo();
dictObj.dictionary = new ADTDictionary();
dictObj.dictionary.read();
Scanner scanner = new Scanner(System.in);
do {
System.out.println("");
System.out.print(">>");
command = scanner.nextLine().trim();
if (!command.equals("exit")) {
dictObj.action(command);
} else {
dictObj.dictionary.saveEntries();
System.out.println("Goodbye! Have a nice day!");
}
} while (!command.equalsIgnoreCase("exit"));
}
public void action(String command) {
if (command.equalsIgnoreCase("LIST ALL")) {
dictionary.listAll();
return;
}
else if (command.toUpperCase().contains("LIST")) {
if (command.length() == 4){
System.out.println("Command needed.");
return;
}
command = command.substring(5, command.length());
dictionary.listDeptName(command);
return;
}
else if (command.toUpperCase().contains("ADD")) {
command = command.substring(4, command.length());
dictionary.add(command);
return;
}
else if (command.toUpperCase().contains("REMOVE")) {
command = command.substring(6, command.length());
dictionary.remove(command);
}
}
}
java file 2
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
public class ADTDictionary {
Map<String, List<String>> adtDictionary;
public void read() {
try {
File facultyFile = new File("faculty.txt");
File departmentFile = new File("departments.txt");
Scanner departmentScanner = new Scanner(departmentFile);
Scanner facultyScanner = new Scanner(facultyFile);
adtDictionary = new HashMap<String, List<String>>();
while (departmentScanner.hasNextLine()) {
String department = departmentScanner.nextLine().trim();
adtDictionary.put(department, new ArrayList<String>());
}
while (facultyScanner.hasNextLine()) {
String faculty = facultyScanner.nextLine();
String[] values = faculty.split(",");
adtDictionary.get(values[1].trim()).add(values[0]);
}
} catch (FileNotFoundException ex) {
System.out.println("ERROR: File not found.");
}
}
public void listAll() {
for (String key : adtDictionary.keySet()) {
for (String value : adtDictionary.get(key)) {
System.out.println(value + ", " + key);
}
}
}
public void listDeptName(String department) {
if (null != adtDictionary.get(department)) {
for (String name : adtDictionary.get(department)) {
System.out.println(name);
}
}
else{
System.out.println("Unknown entry made.");
}
}
public void add(String value) {
if(!value.contains(",")){
System.out.println("Incorrect entry.");
return;
}
String[] values = value.split(",");
String dept = values[0].trim();
String faculty = values[1].trim();
String[] facName = faculty.split(" ");
if (!(facName.length == 2)){
System.out.println("Please only enter First and Last name of faculty member.");
return;
}
if (!(null != adtDictionary.get(dept))) {
if(adtDictionary.containsKey(dept.toUpperCase())){
System.out.println("Incorrect departtment entry.");
return;
}
else if (dept == dept.toUpperCase()){
adtDictionary.put(dept, new ArrayList<String>());
}
else{
System.out.println("Incorrect department entry.");
return;
}
}
for (String name : adtDictionary.get(dept)) {
if (name.equalsIgnoreCase(faculty)) {
System.out.println("Cannot add " + name + " to " + dept + " because they already exist there.");
return;
}
}
adtDictionary.get(dept).add(faculty);
System.out.println("OK, added " + faculty);
}
public void remove(String value) {
String[] values = value.split(",");
String dept = values[0].trim();
String faculty = values[1].trim();
adtDictionary.get(dept).remove(faculty);
System.out.println("OK, removed " + faculty + " from " + dept);
}
public void saveEntries(){
try {
File facultyFile = new File("faculty.txt");
File departmentFile = new File("departments.txt");
PrintWriter facWriter = new PrintWriter(facultyFile);
PrintWriter deptWriter = new PrintWriter(departmentFile);
for (Object s : adtDictionary.keySet()) {
deptWriter.println(s);
}
deptWriter.close();
for (String key : adtDictionary.keySet()) {
for (String value : adtDictionary.get(key)) {
facWriter.println(value + ", " + key);
}
}
facWriter.close();
}
catch (IOException ex){
System.out.println("ERROR saving file.");
}
}
}

Variable cannot be resolved error in Java

I know this is a very very common error but I am stuck on this one and I totally don't understand why is it happening.
Here is a part of my code
import java.util.ArrayList;
import java.util.Scanner;
public class Manager {
private static Scanner sc = new Scanner(System.in);
protected static ArrayList<String> identifications = new ArrayList<String>();
protected static String[] signIn() {
System.out.println("Hi !");
System.out.println("Welcome to School Management System");
System.out.print("Please enter your ID number : ");
boolean idValid = false;
String providedID = null;
int idListPosition = -1;
do {
try {
providedID = sc.nextLine();
} catch (Exception e) {
System.out.println("Sorry there was an error. Please try again");
System.out.print("Please enter your ID number : ");
}
} while (providedID == null);
while (idValid != true) {
for (String element : identifications) {
if (element.equals(providedID)) {
idValid = true;
idListPosition = identifications.indexOf(element);
break;
}
}
if (idValid && idListPosition != -1) {
System.out.println("Welcome !");
String[] returnValue = {"true", identifications.get(idListPosition), identifications.get(idListPosition + 1), identifications.get(idListPosition + 2)};
return (returnValue);
} else {
System.out.println("Error : the ID you entered does not exist. Please try again");
providedID = null;
do {
try {
providedID = sc.nextLine();
} catch (Exception e) {
System.out.println("Sorry there was an error. Please try again");
System.out.print("Please enter your ID number : ");
}
} while (providedID == null);
}
}
}
public static void main(String[] args) {
init();
String[] response = signIn();
if (response[2].equals("teacher")) {
Teacher user = new Teacher(response[1], response[2], response[3]);
}
if (response[2].equals("student")) {
Student user = new Student(response[1], response[2], response[3]);
}
System.out.println(user);
while(true) {
System.out.println("For help type in help");
System.out.print("Enter a command : ");
String commandWanted = sc.nextLine();
if (commandWanted.equals("info")) user.showInfos();
}
}
protected static void init() {
identifications.add("056789");
identifications.add("teacher");
identifications.add("Temperson");
}
}
The Teacher and Student classes are empty for now. I just made them use the super constructor of their parent class Person :
public class Person {
String type;
String name;
String idNumber;
public Person(String idnumber, String newType, String providedName) {
this.idNumber = idnumber;
this.type = newType;
this.name = providedName;
}
protected String[] showInfos() {
String[] returnValue = {this.type, this.name, this.idNumber};
return returnValue;
}
}
But I get user cannot be resolved to a variable and user cannot be resolved error.
Normally the code that needs user will never run unless sign in has completed. And since sign in never ends before a correct ID is entered, the user variable will always be assigned to a a value.
Thanks for helping !

The scope of the user object is limited to the if condition, hence you are getting this error.
If Teacher and Student extends Person then you can try this piece of code:
public static void main(String[] args) {
init();
String[] response = signIn();
Person user = null;
if (response[2].equals("teacher")) {
user = new Teacher(response[1], response[2], response[3]);
}
if (response[2].equals("student")) {
user = new Student(response[1], response[2], response[3]);
}
System.out.println(user);
while(true) {
System.out.println("For help type in help");
System.out.print("Enter a command : ");
String commandWanted = sc.nextLine();
if (commandWanted.equals("info")) user.showInfos();
}
}

You're having a Scope problem here:
if (response[2].equals("teacher")) {
Teacher user = new Teacher(response[1], response[2], response[3]);
}
if (response[2].equals("student")) {
Student user = new Student(response[1], response[2], response[3]);
}
System.out.println(user);
Variables declared in a if block are local to that if block. You can see this in it's simplest form with an example like this:
if(true) {
String value = "Out of Scope";
}
System.out.println(value); //value cannot be seen outside the if block
You will need to declare your Teacher and/or Student variable outside the if block if you wish to use them after the block (this is where using your inheritance class would come in handy). Using the previous example:
boolean someCondition = true;
String value;
if(someCondition) {
value = "In Scope - True";
} else {
value = "In Scope - False";
}
System.out.println(value); //value can now be seen

You have declared 2 different versions of user, so the print statement can't know which you mean. Or it couldn't if it could see either, but since each is declared inside of its own block, the print doesn't see either of them.

Java program not saving object to HashMap

Either my save_product function in my Repository.java class doesn't save correctly into the map product_repository or, maybe it does save, but I'm not outputting it correctly in my find_product function in my Repository.java class. I think I'm using the correct function to search for the value in the map, .get
I experimented with product_repository.keySet().iterator().forEachRemaining(System.out::println); but that's the first time I ever used that... also please forgive how I insert the keyinto the map product_repository in the create_new_product function in the Controller.java class. I'm new to java ...
Main.java
package com.company;
public class Main {
public static void main(String[] args) {
// write your code here
Controller controller = new Controller();
controller.create_new_product();
controller.search_product();
}
}
Product.java
package com.company;
public class Product {
private String product_name;
private String product_brand;
private int product_cost;
private int product_count;
private boolean product_availability;
public Product() {
}
public Product(String product_name, String product_brand,
int product_cost, int product_count, boolean product_availability) {
this.product_name = product_name;
this.product_brand = product_brand;
this.product_cost = product_cost;
this.product_count = product_count;
this.product_availability = product_availability;
}
public String getProduct_name() {
return product_name;
}
public void setProduct_name(String product_name) {
this.product_name = product_name;
}
public String getProduct_brand() {
return product_brand;
}
public void setProduct_brand(String product_brand) {
this.product_brand = product_brand;
}
public int getProduct_cost() {
return product_cost;
}
public void setProduct_cost(int product_cost) {
this.product_cost = product_cost;
}
public int getProduct_count() {
return product_count;
}
public void setProduct_count(int product_count) {
this.product_count = product_count;
}
public boolean isProduct_availability() {
return product_availability;
}
public void setProduct_availability(boolean product_availability) {
this.product_availability = product_availability;
}
}
Controller.java
package com.company;
import java.util.Scanner;
public class Controller {
private static Long key;
public static void create_new_product(){
Repository repository = new Repository();
//Supplier supplier = new Supplier();
Product product = new Product();
Scanner scanner = new Scanner(System.in);
key = 0L;
System.out.println("*****************************************************************");
System.out.println("********************NEW PRODUCT CREATION PAGE********************");
System.out.println("*****************************************************************");
System.out.println("Enter product name: ");
String name = scanner.nextLine();
product.setProduct_name(name);
System.out.println("Enter product brand: ");
String brand = scanner.nextLine();
product.setProduct_brand(brand);
System.out.println("Enter product cost: ");
int cost = scanner.nextInt();
product.setProduct_cost(cost);
System.out.println("Enter amount of products in stock: ");
int amount = scanner.nextInt();
product.setProduct_count(amount);
key++;
repository.save_product(key, product);
}
public void search_product(){
Repository repository = new Repository();
Product product = new Product();
Scanner scanner = new Scanner(System.in);
System.out.println("*****************************************************************");
System.out.println("*************************FIND PRODUCT PAGE***********************");
System.out.println("*****************************************************************");
// TO DO: Choices or if/else blocks not executing properly
System.out.println("\nSearch by ID or name?\nPress '1' for ID. Press '2' for name: ");
String choice = scanner.next();
if (choice.equals("1")) {
System.out.println("Enter product id: ");
Long id = scanner.nextLong();
repository.find_product(id);
try{
if (product.getProduct_count() > 0){
System.out.println(product.getProduct_name() + " are in stock!");
}
} catch (Exception e) {
System.out.println(product.getProduct_name() + " are out of stock.");
}
}
else if (choice.equals("2")) {
System.out.println("Enter product name: ");
String name = scanner.next();
repository.find_product(name);
try{
if (product.getProduct_count() > 0){
System.out.println(product.getProduct_name() + " are in stock!");
}
} catch (Exception e) {
System.out.println(product.getProduct_name() + " are out of stock.");
}
}
else {
System.out.println("Error. We apologize for the inconvenience.");
}
}
}
Repository.java
package com.company;
import java.util.HashMap;
import java.util.Map;
public class Repository {
private Map<Long, Product> product_repository = new HashMap<Long, Product>();
// TO DO: Implement while loops so program doesn't exit at the first error
public void save_product(Long key, Product newProductMap){
try{
if (product_repository.containsValue(newProductMap)) {
System.out.println("This product is already in the system." +
"\nFor safety reasons, we cannot add the same product twice.");
}
else {
product_repository.put(key, newProductMap);
}
} catch (Exception e) {
System.out.println("System error. Consult the database administrator.");
}
}
public void find_product(Long key){
try {
if (product_repository.containsKey(key)) {
System.out.println(product_repository.get(key));
}
else {
System.out.println("No matches were found for product id: " + key);
}
} catch (Exception e) {
System.out.println("System error. Consult the database administrator.");
}
}
// Overload
public void find_product(String name) {
try {
if (product_repository.containsValue(name)) {
System.out.println(product_repository.get(name));
product_repository.keySet().iterator().forEachRemaining(System.out::println);
}
else {
System.out.println("No matches were found for product name: " + name);
}
} catch (Exception e) {
System.out.println("System error. Consult the database administrator.");
}
}
}

You have to make Repository repository a field of your Controller class. You are currently throwing the repositories away after your methods create_new_product and search_product have executed. Therefore you need to remove the first line of each of these methods.
Another problem is inside your find_product(String name) method where your call product_repository.get(name) but name is a String and the get method expects an ID, i.e. a Long so this call will always return null.

As it was pointed out before the repository has to be made global. However, the entire code is a bit messy. You are searching for a product id but the id is not shown to you. It is like searching for database records but the ids are autogenerated. Good luck with that. So I would suggest to allow this program to enter the id as well. It makes much more sense if you want to search for the id.
Otherwise, if you are interested in only the value, id can be taken out.
Below you can find the modified code that works for all the methods.
//main stays the same
public class Main {
public static void main(String[] args) {
// write your code here
Controller controller = new Controller();
controller.create_new_product();
controller.search_product();
}
}
//controller is a bit changed. Added global repository and improved the search.
import java.util.Collection;
import java.util.Scanner;
public class Controller {
private static Long key;
Repository repository = new Repository();
public void create_new_product() {
Product product = new Product();
Scanner scanner = new Scanner(System.in);
System.out.println("*****************************************************************");
System.out.println("********************NEW PRODUCT CREATION PAGE********************");
System.out.println("*****************************************************************");
System.out.println("Enter product id: ");
long id = Long.parseLong(scanner.nextLine());
product.setProductId(id);
System.out.println("Enter product name: ");
String name = scanner.nextLine();
product.setProduct_name(name);
System.out.println("Enter product brand: ");
String brand = scanner.nextLine();
product.setProduct_brand(brand);
System.out.println("Enter product cost: ");
int cost = scanner.nextInt();
product.setProduct_cost(cost);
System.out.println("Enter amount of products in stock: ");
int amount = scanner.nextInt();
product.setProduct_count(amount);
repository.save_product(id, product);
}
public void search_product() {
Scanner scanner = new Scanner(System.in);
System.out.println("*****************************************************************");
System.out.println("*************************FIND PRODUCT PAGE***********************");
System.out.println("*****************************************************************");
// TO DO: Choices or if/else blocks not executing properly
System.out.println("\nSearch by ID or name?\nPress '1' for ID. Press '2' for name: ");
String choice = scanner.next();
if (choice.equals("1")) {
System.out.println("Enter product id: ");
Long id = scanner.nextLong();
Product product = repository.find_product(id);
try {
if (product.getProduct_count() > 0) {
System.out.println(product.getProduct_name() + " are in stock!");
}
} catch (Exception e) {
System.out.println(product.getProduct_name() + " are out of stock.");
}
} else if (choice.equals("2")) {
System.out.println("Enter product name: ");
String name = scanner.next();
Collection<Product> products = repository.find_products(name);
if (products.size() > 0) {
for (Product product : products) {
System.out.println(product.getProduct_name() + " are in stock!");
}
} else {
System.out.println(" out of stock.");
}
} else {
System.out.println("Error. We apologize for the inconvenience.");
}
}
}
//Added a new field to the Repository so you can also search by key.
import java.util.*;
public class Repository {
private Map<Long, Product> product_repository = new HashMap<Long, Product>();
// TO DO: Implement while loops so program doesn't exit at the first error
public void save_product(Long key, Product newProductMap) {
try {
if (!product_repository.containsKey(key)) {
product_repository.put(key, newProductMap);
} else {
System.out.println("This product is already in the system." +
"\nFor safety reasons, we cannot add the same product twice.");
}
} catch (Exception e) {
System.out.println("System error. Consult the database administrator.");
}
}
public Product find_product(final Long key) {
try {
if (product_repository.containsKey(key)) {
System.out.println("Found product: " + product_repository.get(key).getProduct_name());
return product_repository.get(key);
} else {
System.out.println("No matches were found for product id: " + key);
}
} catch (Exception e) {
System.out.println("System error. Consult the database administrator.");
}
return null;
}
// Overload
public Collection<Product> find_products(final String name) {
Collection<Product> values = new ArrayList<>();
for (Map.Entry<Long, Product> productEntry : product_repository.entrySet()) {
if (productEntry.getValue().getProduct_name().equals(name)) {
System.out.println("matches were found for product name: " + name);
values.add(productEntry.getValue());
}
}
return values;
}
}

If statements running simultaneously, if two objects in ArrayList [closed]

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Closed 5 years ago.
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Below is the code. I cannot figure out why in class Database my else if the state runs simultaneously with my if statement IF I have entered the second bird into the ArrayList. please, any help would be appreciated!
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
Database d1 = new Database();
while (true) {
System.out.println("What do you want to do?");
String answer = input.nextLine();
if(answer.equalsIgnoreCase("Add")){
System.out.println("Name: ");
String name = input.nextLine();
System.out.println("Latin name: ");
String lName = input.nextLine();
d1.addBird(name, lName);
} else if (answer.equalsIgnoreCase("O")) {
System.out.println("What was observed?");
String observed = input.nextLine();
d1.Observation(observed);
} else if (answer.equalsIgnoreCase("stats")) {
d1.showBirds(); //Displays all with observations.
} else if (answer.equalsIgnoreCase("show")) {
System.out.println("What?");
String search = input.nextLine();
d1.searchBird(search);
} else if (answer.equalsIgnoreCase("quit")){
break;
}
}
}
}
public class Bird {
private final String name;
private final String latinName;
private int count;
public Bird (String name, String latinName) {
this.name = name;
this.latinName = latinName;
this.count = count;
}
public String getName () {
return this.name;
}
public String getLatin() {
return this.latinName;
}
public String add () {
return this.name + " " + "(" +this.latinName + ")"+ " " + this.count + " observation(s)";
}
public void increaseCount () {
this.count++;
}
}
import java.util.ArrayList;
public class Database {
private final ArrayList<Bird> birdList;
public Database() {
this.birdList = new ArrayList<Bird>();
}
public void addBird (String name, String lname) {
this.birdList.add(new Bird(name, lname));
}
public void Observation (String observed) {
for (Bird x : getBirds()) { // this has to be a method
if (x.getName() != null && x.getLatin() != null && x.getName().contains(observed) || x.getLatin().contains(observed)) {
System.out.println("Done");
System.out.println("");
x.increaseCount();
} else if (x.getName() != observed || x.getLatin() != observed) {
System.out.println("Not a bird");
}
}
}
public void showBirds () {
for (Bird x : this.birdList) {
System.out.println(x.add());
}
}
public ArrayList<Bird> getBirds() {
return this.birdList;
}
public void searchBird(String search) {
for (Bird x : getBirds()) {
if (x.getName().contains(search)) {
System.out.println(x.add());
}
}
}
}

I think the problem lies in this method:
public void Observation (String observed) {
for (Bird x : getBirds()) { // this has to be a method
if (x.getName() != null && x.getLatin() != null && x.getName().contains(observed) || x.getLatin().contains(observed)) {
System.out.println("Done");
System.out.println("");
x.increaseCount();
}
/* No need to print "Not a bird" for every mismatch. Use a flag instead */
else if (x.getName() != observed || x.getLatin() != observed) {
System.out.println("Not a bird");
}
}
}
Do something like this:
public void Observation (String observed) {
boolean found = false;
for (Bird x : getBirds()) { // this has to be a method
if (x.getName() != null && x.getLatin() != null && x.getName().contains(observed) || x.getLatin().contains(observed)) {
System.out.println("Done");
System.out.println("");
x.increaseCount();
found = true;
}
}
if (!found) {
System.out.println("Not a bird");
}
}

Scanner Input not Reading Method Calling as a Parameter

First of All here's the Codes:
Product Information:
public class ProductInformation
{
public String code;
public String itemName;
public double price;
//Constructor
public ProductInformation()
{ itemName="-";
code="-";
price=0;}
//Setter
public void setItemName(String itemName)
{ this.itemName=itemName;}
public void setCode(String code)
{ this.code=code;}
public void setPrice(double price)
{ this.price=price;}
//Getter
public String getItemName()
{ return itemName;}
public double getPrice()
{ return price;}
public String getCode()
{ return code;}
//Products
public void getProduct(String code)
{ if(code == "A001"){
setCode("A001");
setItemName("Mouse ");
setPrice(100);}
else if(code == "A002"){
setCode("A002");
setItemName("Monitor ");
setPrice(2500);}
else if(code == "A003"){
setCode("A003");
setItemName("Keyboard");
setPrice(200);}
else if(code == "A004"){
setCode("A004");
setItemName("Flash Disk");
setPrice(300);}
else if(code == "A005"){
setCode("A005");
setItemName("Hard Disk");
setPrice(1500);}
}
}
import java.util.*;
Product Display:
public class ProductDisplay
{ public ProductInformation product;
public ProductDisplay()
{
System.out.println("\t\t\t\t RG COMPUTER SHOP");
System.out.println("\t\t\t\t Makati City");
System.out.println("\t\tP R O D U C T\tI N F O R M A T I O N");
System.out.println("-------------------------------------------------------");
System.out.println("\t\tCode\t\tDescription\t\tUnit Price");
System.out.println("-------------------------------------------------------");
product = new ProductInformation();
product.getProduct("A001");
display();
product = new ProductInformation();
product.getProduct("A002");
display();
product = new ProductInformation();
product.getProduct("A003");
display();
product = new ProductInformation();
product.getProduct("A004");
display();
product = new ProductInformation();
product.getProduct("A005");
display();
}
// Display Method
public void display()
{ System.out.println("\t\t" + product.getCode()
+ "\t\t" + product.getItemName()
+ "\t\t" + product.getPrice()); }
}
My Problem is here in PointOfSale
I tried to let the buyer decide by entering a Product Code
after entering the getProduct I get is always "A005" Even if I enter "A001" or something else. I think the product.getProduct(code) is not working out. Can someone help me fix this problem so i can continue scripting this
import java.util.*;
public class PointOfSale extends ProductDisplay
{
public PointOfSale()
{ System.out.print("\nPurchase Item(y/n)?");
Scanner sc = new Scanner(System.in);
String line = sc.nextLine();
if("y".equalsIgnoreCase(line)){
OpenOrder();
}
}
//=============================================
public void OpenOrder() // New Order
{ ArrayList<String> ProductList = new ArrayList<String>();
ProductList.add("A001"); ProductList.add("A002");
ProductList.add("A003"); ProductList.add("A004");
ProductList.add("A005");
System.out.print("Select Product Code:");
Scanner sc = new Scanner(System.in);
String code = sc.next();
if(ProductList.contains(code))
{ product.getProduct(code);
display(); EnterQuantity(); }
else System.out.print("Product Code is Invalid\n"); System.exit(0);}
//==============================================
public void EnterQuantity() //Entering Quantity
{
try{
System.out.print("Enter Quantity:");
Scanner sc = new Scanner(System.in);
int quantity = sc.nextInt();
double amount = quantity * product.getPrice();
System.out.print("Amount: " + amount);}
catch (InputMismatchException nfe)
{System.out.print("\nInvalid Entry: Input must be a Number.\n"); System.exit(0);}
}
// Main Method
public static void main(String[] args)
{ new PointOfSale(); }
}

You are comparing strings for equality in your getProduct() method. Strings are objects, so you probably want to use the equals() method:
public void getProduct(String code)
{ if(code.equals("A001")){
setCode("A001");
setItemName("Mouse ");
setPrice(100);}
else if(code.equals("A002")){
setCode("A002");
setItemName("Monitor ");
setPrice(2500);}
else if(code.equals("A003")){
setCode("A003");
setItemName("Keyboard");
setPrice(200);}
else if(code.equals("A004")){
setCode("A004");
setItemName("Flash Disk");
setPrice(300);}
else if(code.equals("A005")){
setCode("A005");
setItemName("Hard Disk");
setPrice(1500);}
}

One major problem is that you're comparing Strings using == and you in general shouldn't do that as this compares if one object reference is the same as another and you don't care about this. Instead you care if the two String variables hold the same String representation, and for this use the equals() or equalsIgnoreCase() methods.