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Trouble accessing data from java program

I'm having a goofy issue. I'm trying to see if I can printout the restaurants and employees data I have here and I can't remember how best to do it this.
Once I can figure out how to do that, I'll be able to create methods using it, but I can't seem to remember how to do it this way.
Updated Code
class Main {
public static void main(String[] args) {
Employee john = new Employee("John","asian",35.00);
Employee sam = new Employee("Sam","Greek",25.00);
Employee michael = new Employee("Michael","Italian",50.00);
Restaurant asian = new Restaurant("Asian","asian",25.00);
Restaurant greek = new Restaurant("greek","greek",25.00);
Restaurant italian = new Restaurant("italian","italian",25.00);
}
public static class Restaurant {
private String restaurantName;
private String cuisine;
private double price;
public Restaurant( String restaurantName,
String cuisine,
double price) {
this.restaurantName = restaurantName;
this.cuisine = cuisine;
this.price = price;
}
public String getRestaurantName() {
return restaurantName;
}
public String getCuisine() {
return cuisine;
}
public double getPrice() {
return price;
}
}
public static class Employee {
private String employeeName;
private String cuisine;
private double budget;
public Employee(String employeeName,
String cuisine,
double budget) {
this.employeeName = employeeName;
this.cuisine = cuisine;
this.budget = budget;
}
public String getEmployeeName() {
return employeeName;
}
public String getCuisine() {
return cuisine;
}
public double getBudget() {
return budget;
}
}
}

For printing out the data of an object you can override the toString method.
After that, the class Restaurant looks like this.
public static class Restaurant {
private String restaurantName;
private String cuisine;
private double price;
public Restaurant( String restaurantName,
String cuisine,
double price) {
this.restaurantName = restaurantName;
this.cuisine = cuisine;
this.price = price;
}
public String getRestaurantName() {
return restaurantName;
}
public String getCuisine() {
return cuisine;
}
public double getPrice() {
return price;
}
#Override
public String toString() {
return "Restaurant [restaurantName=" + restaurantName + ", cuisine=" + cuisine + ", price=" + price + "]";
}
}
the class Employee looks like this.
public static class Employee {
private String employeeName;
private String cuisine;
private double budget;
public Employee(String employeeName,
String cuisine,
double budget) {
this.employeeName = employeeName;
this.cuisine = cuisine;
this.budget = budget;
}
public String getEmployeeName() {
return employeeName;
}
public String getCuisine() {
return cuisine;
}
public double getBudget() {
return budget;
}
#Override
public String toString() {
return "Employee [employeeName=" + employeeName + ", cuisine=" + cuisine + ", budget=" + budget + "]";
}
}
and then you can print an object in sysout
System.out.println(michael);

You have to use a toString method() for each Object's class.
For example in Employee Class:
public String toString()
{
String str = "Employee Name: " + employeeName +
"\nCuisine: " + cuisine + "\nBudget: " + budget;
return str;
}
After that you just have to use the toString() in the main() method:
System.out.println(john.toString());
In the main method you could also use an array to store the data and make it easier to access. Then to display both of the objects inside you could use just one for loop, but I used two to keep the outputs separate from one another.
int numEmployees = 3;
Employee myEmployees[] = new Employee[numEmployees];
myEmployees[0] = new Employee("John","asian",35.00); // Stores John in index 0...
myEmployees[1] = new Employee("Sam","Greek",25.00);
myEmployees[2] = new Employee("Michael","Italian",50.00);
// Displays each object who's index is associated with the value for i
for(int i = 0; i < employees.length; i++)
System.out.println(myEmployees[i].toString());
int numRestaurants = 3;
Restaurant myRestaurants = new Restaurant[numRestaurant]
myRestaurants[0] = new Restaurant("Asian","asian",25.00); // Stores Asain in index 0...
myRestaurants[1] = new Restaurant("greek","greek",25.00);
myRestaurants[2] = new Restaurant("italian","italian",25.00);
// Displays each object who's index is associated with the value for i
for(int i = 0; i < restaurants.length; i++)
System.out.println(myRestaurants[i].toString());

NullPointerException in my function [closed]

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Good day to everyone
I'm new here and in Java, and this is one of first programs with 4 classes and simple methods.
In this prog we put our deal from keybord(we put buyer, seller names, title, price and quantity of products buyed). And so, after I input 2 deals and program must give output I get NullPointerException.
Application.java
package ua.lviv.my;
import java.util.Scanner;
public class Application {
private static Deal [] deal = new Deal[2];
public static void main(String[] args) {
new Application().allActions();
}
void allActions(){
input();
System.out.println("======================");
output();
}
public void output(){
for(int i=0; i<deal.length; i++){
System.out.println("Buyer :" +deal[i].getBuyer().getName());
System.out.println("Seller :" +deal[i].getSeller().getName());
for (int j = 0; j < deal[i].getProducts().length; j++) {
System.out.println("Buys " +deal[i].getProducts()[j].getTitle() +"for " +deal[i].getProducts()[j].getPrice() + " in quantity " +deal[i].getProducts()[j].getQuantity());
}
}
}
public void input(){
for (int i=0; i<deal.length; i++){
deal[i]=inputDeal();
}
}
public Members inputMember(String msg){
Members members = new Members();
String memberName = keybordIn(msg);
members.setName(memberName);
return members;
}
public Product inputProduct(){
Product product =new Product();
String titleStrng = keybordIn("Enter product title");
String priceStrng = keybordIn("Enter product price");
String quantityStrng = keybordIn("Enter quantity");
double price=Double.parseDouble(priceStrng);
int quantity = Integer.parseInt(quantityStrng);
product.setTitle(titleStrng);
product.setPrice(price);
product.setQuantity(quantity);
product.getCost(price, quantity);
return product;
}
public Deal inputDeal(){
Members buyer = inputMember("Enter buyer name :");
Members seller =inputMember("Enter seller name :");
Product [] products = new Product[2];
for(int i=0; i<products.length; i++){
products [i]=inputProduct();
}
Deal deal = new Deal(buyer, seller, products);
return deal;
}
public String keybordIn(String msg){
System.out.println(msg);
Scanner scan = new Scanner(System.in);
String in = scan.next();
return in;
}
}
Deal.java
package ua.lviv.my;
import java.util.Date;
public class Deal {
private Date date = new Date();
private Members buyer;
private Members seller;
private Product[] products = new Product[2];
public Deal(Members buyer, Members seller, Product[] products) {
}
public Date getDate() {
return date;
}
public Members getBuyer() {
return buyer;
}
public Members getSeller() {
return seller;
}
public Product[] getProducts() {
return products;
}
public double inTotal() {
double summ = 0;
for (int i = 0; i < products.length; i++) {
summ += products[i].getCost(products[i].getPrice(),
products[i].getQuantity());
}
return summ;
}
}
Members.java
package ua.lviv.my;
public class Members {
String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
package ua.lviv.my;
public class Product {
private String title;
private double price;
private int quantity;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
public double getCost(double price, int quantity){
double cost = price*quantity;
return cost;
}
}

Start by taking a look at the constructor for Deal...
public Deal(Members buyer, Members seller, Product[] products) {
}
You never assign any of the values passed via the constructor to the member fields, for example...
public Deal(Members buyer, Members seller, Product[] products) {
this.buyer = buyer;
this.seller = seller;
this.products = products;
}

My objects values won't save. Displays null

I have 3 classes:
Sportswear (superclass)
Jersey (subclass)
Driver
I have an ArrayList in my driver to hold all my jerseys created.
When the user inputs all the values (stock, price, product, team, kit, size, gender),
and it displays them back it shows null :
Product: null
In stock: 0
Price: 0
Team:
Kit:
Size:
Gender:
The superclass (Sportswear) has the variables stock, price and product (so I can include other products, not just jerseys)
And the subclass (Jersey) contains the variables team, kit, size, gender. It also contains the method jerseyDisplay() which shows what is above.
In the driver after the values are inputted I put:
Jersey jersey = new Sportswear(stock, price, product, team, kit, size, gender);
sportswear.add(jersey);
jersey.jerseyDisplay();
Is this completely wrong? Why arn't the inputted values showing up?
The jerseyDisplay() method in the subclass Jersey is:
public void jerseyDisplay()
{
super.sportswearDisplay();
System.out.println("Team: "+team);
System.out.println("Kit: "+kit);
System.out.println("Size: "+size);
System.out.println("Gender: "+gender);
}
#DessertIvy This is the Sportswear superclass:
public class Sportswear
{
//instance variables
private int stock;
private float price;
private String product;
//blank constructor
public Sportswear()
{
this.stock = 0;
this.price = 0;
this.product = "";
}
//detailed constructor
public Sportswear(int s, float p, String pd)
{
this.stock = stock;
this.price = price;
this.product = product;
}
//setters
public void setStock(int stock)
{
this.stock = stock;
}
public void setPrice(float price)
{
this.price = price;
}
public void setProduct(String product)
{
this.product = product;
}
//getters
public int getStock()
{
return stock;
}
public float getPrice()
{
return price;
}
public String getProduct()
{
return product;
}
//increase stock
public int increaseStock()
{
stock = stock++;
return stock;
}
//decrease stock
public int decreaseStock()
{
stock = stock - 1;
return stock;
}
public void sportswearDisplay()
{
System.out.println("Product: "+product);
System.out.println("In stock: "+stock);
System.out.println("Price: "+stock);
}
}
The constructor in the Jersey subclass:
public Jersey(int stock, float price, String product, String team, String kit, String size, String gender)
{
super(stock, price, product);
this.team = "";
this.kit = "";
this.size = "";
this.gender = "";
}

The problem are within your 2 contructors :
//detailed constructor
public Sportswear(int s, float p, String pd)
{
this.stock = stock;
this.price = price;
this.product = product;
}
and
public Jersey(int stock, float price, String product, String team, String kit, String size, String gender)
{
super(stock, price, product);
this.team = "";
this.kit = "";
this.size = "";
this.gender = "";
}
You should initialize your variables with the values passed as parameters... or use your setXXX methods. In the constructor, it should look like this :
//detailed constructor
public Sportswear(int s, float p, String pd)
{
this.stock = s;
this.price = p;
this.product = pd;
}
Also, as mentionned earlier, this line
Jersey jersey = new Sportswear(stock, price, product, team, kit, size, gender); shouldn't even compile... you probably meant Jersey jersey = new Jersey(stock, price, product, team, kit, size, gender);

How do I override a method in a subclass?

I have an inventory program written to include an array and a method to calculate total cost for all inventory items entered. I now have to include a subclass that overrides the original to include "one unique feature". I created a new file named ItemDetails to set up for the subclasses of the original Item. I need to include one unique feature and calculate the value of the inventory and calculate a 5% restocking fee in this subclass. Do I just transfer some of the relevant lines into the other class? Or do I write some code twice? I don't know what to do next. Any help is useful. Thanks. This is what I have so far:
package inventory3;
public class ItemDetails extends Items
{
public static void override()
{
private String Name;
private double pNumber, Units, Price;
public ItemDetails()
{
}
}
}
This is the Item class file that it is supposed to override:
package inventory3;
import java.lang.Comparable;
public class Items implements Comparable
{
private String Name;
private double pNumber, Units, Price;
public Items()
{
Name = "";
pNumber = 0.0;
Units = 0.0;
Price = 0.0;
}
public int compareTo(Object item)
{
Items tmp = (Items) item;
return this.getName().compareTo(tmp.getName());
}
public Items(String productName, double productNumber, double unitsInStock, double unitPrice)
{
Name = productName;
pNumber = productNumber;
Units = unitsInStock;
Price = unitPrice;
}
//setter methods
public void setName(String n)
{
Name = n;
}
public void setpNumber(double no)
{
pNumber = no;
}
public void setUnits(double u)
{
Units = u;
}
public void setPrice(double p)
{
Price = p;
}
//getter methods
public String getName()
{
return Name;
}
public double getpNumber()
{
return pNumber;
}
public double getUnits()
{
return Units;
}
public double getPrice()
{
return Price;
}
public double calculateTotalPrice()
{
return (Units * Price);
}
public static double getCombinedCost(Items[] item)
{
double combined = 0;
for(int i =0; i < item.length; ++i)
{
combined = combined + item[i].calculateTotalPrice();
}
return combined;
}
}

You simply declare a method with the same signature as the method in the parent class. So yours would look like:
package inventory3;
public class ItemDetails extends Items {
private String Name;
private double pNumber, Units, Price;
public ItemDetails(String Name, double pNumber, double Units, double Price) {
this.Name = Name;
this.pNumber = pNumber;
this.Units = Units;
this.Price = Price;
}
// getters and setters....
// The #Override is optional, but recommended.
#Override
public double calculateTotalPrice() {
return Units * Price * 1.05; // From my understanding this is what you want to do
}
}

Create a default constructor in Java

I need to create a method with a default constructor, which sets name to an empty string and sets both credits and contactHours to zero. How to do it? Thanks, Pieter.

Methods don't have constructors... classes do. For example:
public class Dummy
{
private int credits;
private int contactHours;
private String name;
public Dummy()
{
name = "";
credits = 0;
contactHours = 0;
}
// More stuff here, e.g. property accessors
}
You don't really have to set credits or contactHours, as the int type defaults to 0 for fields anyway.
You're likely to want at least one constructor which takes initial values - in which case your parameterless one can delegate to that:
public class Dummy
{
private String name;
private int credits;
private int contactHours;
public Dummy()
{
this("", 0, 0);
}
public Dummy(String name, int credits, int contactHours)
{
this.name = name;
this.credits = credits;
this.contactHours = contactHours;
}
// More stuff here, e.g. property accessors
}

public class Test {
private String name;
private int credits;
private int contactHours;
public Test {
this( "", 0, 0);
}
public Test (String name, int credits, int contactHours) {
this.name = name;
this.credits = credits;
this.contactHours = contactHours;
}
// more code here
}

public class Bibabu{
private String name;
private int credits;
private int contactHours;
public Bibabu(){
name = ""; // you could also write this.name and so on...
credits = 0;
contactHours= 0;
}
// more code here
}

You don't need a constructor:
public class Dummy
{
private int credits = 0;
private int contactHours=0;
private String name="";
/*
public Dummy()
{
name = "";
credits = 0;
contactHours = 0;
}
*/
// More stuff here, e.g. property accessors
}

//constructor
public Account(int id, double balance, Person owner){
this.id = id;
this.balance = balance;
this.owner = owner;