i am trying to write a class which has an array of a subclass in the same project, and when i am trying to write a method that will add a new object to the array on condition that this object is not already in the array, and also if the specific cell is free, so the object will enter to the array.
but the problem is that i need to insert a variable to this method which is the copy constructor's object.
the problem is that in the subclass i don't know how to write the copy constructor.
so i will give a short example of 2 classes and you will show me how to write a copy constructor with them :
public class Food
{
private String _foodName;
public Food(String foodName)
{
_foodName=foodName;
}
public String getFoodName()
{
return _foodName;
}
public void showName()
{
System.out.println("The food's name is: " +_getFoodName());
}
}
public class Apple extends Food
{
private int _numOfApples;
public Apple(String name, int numOfApples)
{
super(name);
_numOfApples=numOfApples;
}
public Apple(Apple other)
{
????
}
}
how does the copy constructor should looks like ?
thank you for your help :)
By invoking the other constructor. Like,
public Apple(Apple other) {
this(other.getFoodName(), other._numOfApples);
}
I cannot help you properly because i cannot understand entirely what you are trying to do but at least i can help you correct some mistakes in your code:
public class Food
{
private String food;
public Food(String foodName)
{
food = foodName;
}
public String getFoodName()
{
return food;
}
public void showName()
{
System.out.println("The food's name is: " + getFoodName());
}
}
public class Apple extends Food
{
private int numOfApples;
public Apple(String name, int numberOfApples)
{
super(food);
numOfApples=numberOfApples;
}
public Apple(Apple copy)
{
this.name = copy.name;
this.numOfApples = copy.numOfApples;
}
}
Hope this helps.
Related
Novice java coder here, expert java drinker. I've been working on an assignment for my class all day where I have to write a java class known as "Pet" for a fictional program called Pet BAG(Boarding and grooming) for my fictional employer Global Rain. Anyway, I have alot of said code written, and am continuing to work on it dilligently however I have hit a roadblock. When I try the instant feed back tool I get "getDogSpaces()" or "getCatSpaces()" functions seem to be missing. Can anyone help me understand why I get this error so I can fix it and move on? I am stunped. My code is posted below.
public class Pet {
//Atrributes
private String petType;
private String petName;
private int petAge;
private int dogSpaces;
private int catSpaces;
private int daysStay;
private double amountDue;
public Pet (String petType, String petName, int petAge, int daysStay) {
setPetType(petType);
setPetName(petName);
setPetAge(petAge);
setDogSpace(30);
setCatSpace(12);
setDaysStay(daysStay);
}
//Accessors
public String getPetType() {
return petType;
}
public String getPetName() {
return petName;
}
public int getPetAge() {
return petAge;
}
public void setPetAge(int setPetAge) {
this.petAge = petAge;
}
public int getDogSpace() {
return dogSpace;
}
public void setDogSpace(int dogSpace) {
this.dogSpace = dogSpace;
}
public int getCatSpace() {
return catSpace;
}
public void setCatSpace(int catSpace) {
this.catSpace = catSpace;
}
public int getDaysStay() {
return daysStay;
}
public void setDaysStay(int daysStay) {
this.daysStay = daysStay;
}
public double getAmountDue() {
return amountDue;
}
public void setAmountDue(double amountDue) {
this.amountDue = amountDue;
}
}
I know my code block seems strange, but I did my best to line it up properly. Could anyone assist me?
Thank you,
Joseph
Sorry as I know this is obvious but I cant figure it out!
I have a parent class named 'Set', representing a set of a tennis match.
public class Set {
private String set1;
private String set2;
private String set3;
//private Object[] match;
public Set() {
setSet1(set1);
setSet2(set2);
setSet3(set3);
}
public void setSet1(String set1) {
this.set1 = set1;
}
public String getSet1() {
return set1;
}
public void setSet2(String set2) {
this.set2 = set2;
}
public String getSet2() {
return set2;
}
public void setSet3(String set3) {
this.set3 = set3;
}
public String getSet3() {
return set3;
}
public String toString(){
return String.format("set1: %s, set2: %s, set3: %s", set1, set2, set3);
}
}
And a sub class of 'Set' named 'SingleSet', where i try to add the sets into an array named 'game':
public class SingleSet extends Set{
private Object homePlayer;
private Object awayPlayer;
private String[] game;
public SingleSet(Object homePlayer, Object awayPlayer){
super();
game = new String[3];
game[0] = super.getSet1();
game[1] = super.getSet2();
game[2] = super.getSet3();
setHomePlayer(homePlayer);
setAwayPlayer(awayPlayer);
}
public void setHomePlayer(Object homePlayer) {
this.homePlayer = homePlayer;
}
public Object getHomePlayer() {
return homePlayer;
}
public void setAwayPlayer(Object awayPlayer) {
this.awayPlayer = awayPlayer;
}
public Object getAwayPlayer() {
return awayPlayer;
}
public void setGame(String[] game) {
this.game = game;
}
public String[] getGame() {
return game;
}
public String toString(){
return String.format("Player: %s Vs. Player: %s, Single set game: %s, %s, %s", homePlayer, awayPlayer, game[0], game[1], game[2]);
}
}
And this is where I am trying to add the Sets from my parents class into my sub class (this is for FXML, so the code is in my controller):
public void submit() {
SingleSet game1 = new SingleSet(homePlayer1Dropdown.getValue(), awayPlayer1Dropdown.getValue());
game1.setSet1(set1Box1.getText());
game1.setSet2(set1Box2.getText());
game1.setSet3(set1Box3.getText());
System.out.println(game1);
When I print the result, all my values are null. I tried printing them individually and that worked fine, so I know the 'set1Box.getText()' is working fine.
Again sorry for any obvious rookie error!
I've updated my code and same issue. Thank you for the composition answer, I will need it for my project, but this is a IS-A relationship
Make sure that the toString() methods of the following attributes exist and return a correct string.
It seems as if there is no way to get a String from homePlayer, awayPlayer and all indices of game[x].
public String toString(){
return String.format("Player: %s Vs. Player: %s, Single set game: %s, %s, %s", homePlayer, awayPlayer, game[0], game[1], game[2]);
}
Assume that I used decorated design pattern for making a pizza. There are 3 type of ingredients that user can add his pizza. Mozarella, souce and vegetables. I prepared these classes and set the cost.
This is main code
public class PizzaFactory {
public static void main(String[] args) {
Pizza p = new TomatoSauce(new Mozarella(new PlainPizza()));
System.out.println(p.getIngredients());
}
}
This is interface
public interface Pizza {
public String getIngredients();
public int getCost();
}
This is base pizza
public class PlainPizza implements Pizza{
#Override
public String getIngredients() {
return "Pizza ";
}
#Override
public int getCost() {
return 5;
}
}
This is decorator class
abstract class IngredientDecorator implements Pizza{
protected Pizza tempPizza;
public IngredientDecorator(Pizza newPizza) {
this.tempPizza = newPizza;
}
public String getIngredients() {
return tempPizza.getIngredients();
}
public int getCost() {
return tempPizza.getCost();
}
}
One of ingredient class is
public class Mozarella extends IngredientDecorator{
public Mozarella(Pizza newPizza) {
super(newPizza);
}
public String getIngredients() {
return tempPizza.getIngredients() + " Mozarella";
}
public int getCost() {
return tempPizza.getCost() + 1;
}
}
Others are look like them.
Now, I want to take input from user to which ingradient they want. In order to input I will create pizza. They may want just plain pizza. But since, I create my pizza -> Pizza p = new TomatoSauce(new Mozarella(new PlainPizza())); like this. How can I create pizza dinamic? Do I have to check each condition with if-else or switch-case?
I am trying to sort an ArrayList in increasing order in reference to a certain variable. This is the problem question.
q5: Create a public class named Snow with private instance variables vast, prior, ethnic, and remarkable each of type int. You may add any other methods and variables you'd like to this class.
Outside of Snow (in the Problem Set class) write a public static method named sortSnow that takes an ArrayList of Snows as a parameter and returns void. This method will sort the input by the variable remarkable in increasing order
This is what I wrote.
public class snow implements Comparable<snow> {
private int vast;
private int prior;
private int ethnic;
private int remarkable;
public snow( int vast , int prior, int ethnic ,int remarkable) {
this.vast=vast;
this.prior = prior;
this.ethnic = ethnic;
this.remarkable = remarkable;
}
public int getEthnic() {
return ethnic;
}
public void setEthnic(int ethnic) {
this.ethnic = ethnic;
}
public int getPrior() {
return prior;
}
public void setPrior(int prior) {
this.prior = prior;
}
public int getVast() {
return vast;
}
public void setVast(int vast) {
this.vast = vast;
}
public int getRemarkable() {
return remarkable;
}
public void setRemarkable(int remarkable) {
this.remarkable = remarkable;
}
public int compareTo(snow compareSnow) {
// TODO Auto-generated method stub
int compareThese = ((snow) compareSnow).getRemarkable();
//ascending order
return this.remarkable - compareThese;
}
}
public static void sortSnow(ArrayList<snow>input){
Collections.sort(input);
}
I am not understanding what the error means. The autolab is giving me this error:
Could not find class submission.ProblemSet$Snow
Java is case sensitive i.e. snow is not Snow is not sNoW. Rename your class to Snow and try again. Also, it is ArrayList and not arraylist.
Then to sort a List, you can use Collections.sort.
I think this is you want to achieve
Save below code in file called "Snow.java" compile it and try to run it.
import java.util.ArrayList;
import java.util.Collections;
//As ".java" file can contain only single public java class
//I made Problem set class non-public so we can use its main method
//to run and see output
class ProblemSet {
public static void main(String[] args) {
Snow one = new Snow(1,1,1,1);
Snow two = new Snow(1,1,1,2);
Snow three = new Snow(1,1,1,3);
Snow four = new Snow(1,1,1,4);
Snow five = new Snow(1,1,1,5);
Snow six = new Snow(1,1,1,6);
ArrayList arrayList = new ArrayList();
arrayList.add(one);
arrayList.add(three);
arrayList.add(five);
arrayList.add(two);
arrayList.add(six);
arrayList.add(four);
System.out.println("Without sort");
System.out.println(arrayList);
sortSnow(arrayList);
System.out.println("With sort");
System.out.println(arrayList);
}
//this is your static method which takes argument as array list of Snow
//And it applies sorting logic based on compareTo method which you wrote
//in Snow class. As per java best practice Class name should start with
//Upper case letters and follow camel casing I renamed your class from
//"snow" to "Snow"
public static void sortSnow(ArrayList<Snow> input){
Collections.sort(input);
}
}
//This is you public class Snow
//If you want to keep it in separate java file put it
public class Snow implements Comparable<Snow> {
private int vast;
private int prior;
private int ethnic;
private int remarkable;
public Snow(int vast, int prior, int ethnic, int remarkable) {
this.vast = vast;
this.prior = prior;
this.ethnic = ethnic;
this.remarkable = remarkable;
}
public int getEthnic() {
return ethnic;
}
public void setEthnic(int ethnic) {
this.ethnic = ethnic;
}
public int getPrior() {
return prior;
}
public void setPrior(int prior) {
this.prior = prior;
}
public int getVast() {
return vast;
}
public void setVast(int vast) {
this.vast = vast;
}
public int getRemarkable() {
return remarkable;
}
public void setRemarkable(int remarkable) {
this.remarkable = remarkable;
}
public int compareTo(Snow compareSnow) {
// TODO Auto-generated method stub
int compareThese = ((Snow) compareSnow).getRemarkable();
//ascending order
return this.remarkable - compareThese;
}
//This is added because when you use array list to print
//it will print remarkable of particular Snow object
#Override
public String toString() {
return String.valueOf(remarkable);
}
}
I am trying to practice with Polymorphism and using classes. I wrote a superclass called Card. I then wrote 3 subclasses called: IDCard, CallingCard, and DriverLicense. I then wrote another class called Billfold which is supposed to contain slots for two of the cards.
I am supposed to write a BillfoldTester program which adds two objects of different subclasses to a Billfold object.
In BillfoldTester, a DriverLicense object and a CallingCard object are instantiated and added to a Billfold, which refers to these objects with Card references.
I don't really understand how to do this. I created two Card objects but I am trying to add it to my Billfold and it wont work. I tried Billfold a = new Card (x); but it's not right... Any help is much appreciated.
public class BillfoldTester
{
public static void main (String[]args)
{
Card x= new IDCard("Julie", 1995);
Card j= new DriverLicense("Jess", 1997);
//Having trouble trying to put the objects into my Billfold and print it.
}
}
public class Billfold extends Card
{
private String card1;
private String card2;
void addCard(String Card)//Not sure if this should be String
{
card1=Card;
}
}
public class Card
{
private String name;
public Card()
//This is my superclass
{
name = "";
}
public Card(String n)
{
name = n;
}
public String getName()
{
return name;
}
public boolean isExpired()
{
return false;
}
public String format()
{
return "Card holder: " + name;
}
}
public class IDCard extends Card
{
//This is one of my subclasses
private int IDNumber;
public IDCard (String n, int id)
{
super(n);
this.IDNumber=id;
}
public String format()
{
return super.format() + IDNumber;
}
}
The polymorphism example. Not sure if the functionally is exactly what you need, but you can see the whole idea (I hope). See the showAllFormat() method of Billfold class.
The whole point is inside different format() methods of the DriverLicense and IDCard. Depending on the 'real' (or initially assigned) object the different method will be called even if you just only refer to 'Card' class.
NOTE:
You didn't provide your DriverLicense implementation, and my is just from head. I have a bit different constructor to show this sub-classes may be totally different.
import java.util.ArrayList;
import java.util.List;
class Billfold {
List<Card> list = new ArrayList<Card>(10);
void addCard(Card card) // Q: Not sure if this should be String
// A: You would like to add a Card
{
list.add(card);
}
void showAllFormat() {
// go polymorphism !...
// when you call this general 'format()' you see the subclasses
// 'format()' is executed, not from 'Card' class
for(Card x: list) {
System.out.println(x.format());
}
}
}
class Card {
private String name; /* owner */
public Card() //This is my superclass
{
name = "";
}
public Card(String n) {
name = n;
}
public String getName() {
return name;
}
public boolean isExpired() {
return false;
}
public String format() {
return "Card holder: " + name;
}
}
class IDCard extends Card {
//This is one of my subclasses
private int IDNumber;
public IDCard(String n, int id) {
super(n);
this.IDNumber = id;
}
public String format() {
return "(ID)" + super.format() + " " + IDNumber;
}
}
class DriverLicense extends Card {
private String type;
public DriverLicense(String n, String type) {
super(n);
this.type = type;
}
public String format() {
return "(DL)" + super.format() + " TYPE: " + type;
}
}
public class BillfoldTester {
public static void main(String[] args) {
Card x = new IDCard("Julie", 1995);
Card j = new DriverLicense("Jess", "AB");
Billfold bf = new Billfold();
bf.addCard(x);
bf.addCard(j);
bf.showAllFormat();
}
}
This is wrong. A Billfold is not a Card; it HAS Cards.
public class Billfold
{
List<Card> cards = new ArrayList<Card>();
void addCard(Card card) {
if (card != null) {
this.cards.add(card);
}
}
}
Prefer composition over inheritance.
You should have Billfold class have two Card objects, not two Strings:
public class Billfold
{
Card card1;
Card card2;
void addCard(Card card) {
if (card != null) {
if (card1 != null) {
this.card1 = card;
} else {
this.card2 = card;
}
}
}
Ok, you're largely on the right track, just a couple of things:
void addCard(String Card)//Not sure if this should be String
{
card1=Card;
}
You're right, this should be:
void addCard(Card card)
{
card1=card;
}
then to add them:
public class BillfoldTester
{
public static void main (String[]args)
{
Card x= new IDCard("Julie", 1995);
Card j= new DriverLicense("Jess", 1997);
Billfold bf = new Billfold();
Billfold.addCard(x);
Billfold.addCard(j);
}
}
Then add a method to Billfold to print the cards in it.
Edit: Oh yeah, and duffymo is totally right, you don't need to extends Card on Billfold