I have a list of objects in my bean (ex: List<Apple> applies = new ArrayList<Apple>() ).The object has several fields (ex: supplier, color, width, height, breadth, etc.)I want to show this list on the front end. However I also want to allow the user to edit the attributes of the apples.So from the front end I will have like a list of fields where a set of fields is related to a single object in the list.I would also like to add/delete apples.
What first came to my mind is to map every field in the object Apple to a List. For example if Apple has field suppliers and field color then in the bean I would create two Lists, List<String> supplier, and List<String> color.From the front end I would display the contents of these Lists rather then the List<Apple> apples.T
he name of the field would be the same for each set of attributes.On save (form submit) the Lists would be re-populated with the field values (changed or not) and then I would be my Apple objects from the bean before saving in database.However I am not sure if there is something in JSF that can achieve this in a simple way, working only with List<Apple> rather than adding additional Lists.
Exercise the Coin class using a driver class in which 5 coins are flipped, as a group, 1024 times. Display the number of times exactly 4 tails are obtained. Display the number of times exactly 5 tails are obtained. Use an array of Coin.
how to put an object into an array?I know how to make a coin class with a Heads and Tails, but I dont know how to make 5 coins all at once.
I know the first line below creates an object but the second line creates an array of cars, I'm just not sure how it does that. I can see sportsCar is one object in the array but the others are written in a different way. It seems there should a couple names there instead. Please explain the syntax in this code that's highlighted. I don't know how to make sense of it and I've read through the book where I got it where it explained creating objects.
Auto sportsCar = new Auto("Ferrari", 0, 0.0); Auto [] cars = {new auto("BMW", 100, 15.0), sportsCar, new Auto()};
okay,I created a program that demonstrated an array holding a number of objects, each from different classes.the printout I got for the first program ended up being gibberish. when I made the program a second time, I got the correct result.I've been trying to pinpoint the anomaly but I can't seem to find it. So ill try breaking down what I did?
Goal:The purpose of the program was to have a single Class (we'll call the Class 'Animal') to pass the parameters of a previously made method. This method would, amongst other things, call on an array.Further, I would then make subclasses of the Class Animal, and then use them as well to pass the method parameters, thus demonstrating subclasses can be used in place of the super class.
3 of these classes were made purely to as a "place setter". the Classes called "Cat" and "Dog" respectively were created to be subclasses of the Class Animal (with no other code inside them aside from "extends Animal)the 3rd "place setter" called "ClasstoHoldObjects" was created to be the array class (ClasstoHoldObjects itself has no code in it aside from the class name)these are the ones we want.Animal class (which holds the coding meant to be used).Here is the Animal Class
public class Animal { private ClasstoHoldObjects[] thelist = new ClasstoHoldObjects[5]; int i = 0; public void add(ClasstoHoldObjects x){ if(i < thelist.length){
[code]....
the print out was this next, im putting THIS line in the array... june_6.Dog@a0dcd9 (and the same by the Cat object).I recognize june6 as the package name.
finally, I erased extra lines as well as comments and simplified class names to make the code more readable. If you want the original, or some class names are a bit off- I could give you the original with all its comments and longer named classes
I have a program I want to make (text based, no gui). There is the main class, an Employee class (sort of a template), a CrewMember class, and a Manager class.
I'll put the code for each class an explain the problem I have.
package polymorphism; import java.util.Random; public class Start { public static void main(String[] args) { Random rand = new Random(); Employee staff[] = new Employee[5]; for(int i = 0; i < staff.length; i++){
[Code] ....
Some of the code is a bit incomplete simply because I ran into the problem. As you can see I made an array in the Start class and it holds objects of Employee type, but create a new instance of either a crew member or a manager, sets their wages, hours, and bonus if applicable. I know if I create an array of a certain type, I can't call upon the subclass' method (Manager in this case) because it has a new method that I added. What I'm trying to do is pretty much call upon the getSalary() method in the Manager class/object, but of course I can't. What way would i be able to do that? I tried looking for some answers. I read about making the superclass abstract and implementing it into the subclasses. Would that be an option?
An array has objects with String firstName, String lastName, int ID, char examType('M' or 'F'), and int score. Every object has both Midterm('M') and Final('F'). The array has to be sorted by the first Midterm- 'M' and immediately followed by the Final ('F') of the same person (object). Im having troubles with coming up with a proper algorithm with gettin the Final- 'F' after Midterm for the same person.
Java Code: public static Exam[] collateExams(Exam[] exams) { Exam [] r = new Exam[10]; r = exams; int[] position = new int[10]; int index = 0; for(int i = 0; i < exams.length; i++)
I have an assignment where I need to add an interface to an already-created program. I have an array of objects, where each object has a name, price, and priority.
In my original program (which worked), I had all of the objects in 1 class. The professor said that I should split up the name/price/priority into 3 different classes. So what I have is an array that belongs to an interface, and name/price/priority implements. But I am having trouble loading the data into the array (from another class) once I am done with loading name.
Here is what I have so far.
public class Main { public static void main (String[] args){ Interface[] arr = new Interface[7]; Scanner keyboard = new Scanner(System.in); System.out.println
[code]....
Line 18 in the ItemName class is giving me an error, and I know it is because arr is of type Interface, and I am trying to assign is a String. But I don't know how to do this. In my original program I was able to do arr[x].getName(); but when I do that in Main, I get errors.
how to assign to an interface array from multiple classes.
'm working on a program that is to act as an inventory for a book store. There are two classes (Store and Book), and numerous methods which you will see in my code. The program is supposed to read in an inventory from a file which contains 10 books (each row in the file represents a book with an ISBN number, the price of the book, and the number in stock)and store this file into an array of type Book[]. There is then to be another method to process a purchase interactively. The Store class is also to keep a count of how many books were sold at the time of closing and also how much was made that day.
I'm having some difficulty figuring out how I should set up the purchase processing method though. I've written out how I think it would be set up (not too familiar with the terminology, but I think it would be called pseudo code?) I'll include that now along with a few other notes.
public Book[] purchase(String isbn, double price, int copies) { int itemsSold; double totalMade; Scanner input = new Scanner(System.in); System.out.println("Please enter the ISBN number of the book you would like to purchase: ");
[Code] ....
So basically here's what needs to be accomplished with this portion of code:
1.Ask the user to enter the ISBN number of the book they'd like to purchase. 2.Search the array for the object that contains that ISBN. 3.If the ISBN isn't found in the array, display a message stating that we don't have that book. 4.If the ISBN is found but the number of copies is 0, display a message saying the book is out of stock. 5.If the ISBN is found and the number of copies is greater than 0, ask the user how many copies they'd like to purchase. 6.If the number they enter is greater than the number of copies of that book in the array, display a message stating that and ask them to enter another quantity. 7.Once the purchase is complete I need to update the array by subtracting the number of copies of that particular book that was purchased. 8.Print the updated array. 9.Display a count of how many books were purchased, and how much money was made from the purchase.
I know that code has a lot of holes in it, but I'm just trying to get everything together and figure out how to do each step.
The part I'm stuck on right now is trying to figure out how to search the array to first see if the ISBN that was entered is in the array, and then to find the number of copies of the book with that ISBN number.
In case it will visualize what this array looks like, here's a print out of the array from a sample run I just did.
if, instead of an ArrayList, can I do the following to initialize a Dyanmic array ? :
First, in my class, I have :
class Example{ private int rows; private int columns; private AnotherClass[][] 2DArray; public Example(int rows, int columns){ this.rows = rows; this.columns = columns;
I want to keep count of how many students are in my array. the array i made up of objects from other classes. like the class Student how do i do this. i have tried contains but better way it to to a loop to go through the array and determine if each object is a particular type but i don't know how to do this. here is the code
import java.util.*; import java.util.ArrayList; public class Driver { public static void main(String[] args){ /* Comments required PersonFileReader pfr = new PersonFileReader("person.dat"); ArrayList<Person> testData = pfr.readData(); Database db = new Database(testData);
I want to create a simple app that takes a name from the console then compares the name to a small phone book,when the name matches another name it will return the associated phone number.
I have a small contacts class which has name and number fields,Then I have a phone book class which populates an array with 4 contact objects that I can compare the entered number against.
here is my contacts class
public class Contact { String name; int number;
[Code].....
In the main method I am just trying to print out one of the fields for one contact to see if I can actually access it to compare it to the name entered.Its saying "MaryJones" cannot be resolved to a type.I'm guessing I cant create all that code in the constructor?
I am trying to build a method that takes an array of object and adds a new object of that type to the end of it . ONLY ALLOWED TO USE ARRAY , NO ARRAYLISTS VECTORS ECT . i realize that if the array is full you can use the java copy array method to make a new array and double its size until a certain point . The MAX AMOUNT OF OBJECTS is a constant that is 100 but for some reason even when executing my code i keep getting null pointer exceptions or index out of bounds errors , i have written this method many times now with out any success.
My question is how do I write a method that adds an object to the end of an array and if there are no spots left copies the current array into a new array and extend the size
private Animal [] objects; final int MAX_ANIMALS = 100; public AnimalObject() { objects = new AnimalObject[MAX_ANIMALS]; } public AnimalObject(Animal[]a)
I'm working on a project that involves the following:
-Creating a superclass of bankaccounts -Creating two subclasses, checkingaccount and savingaccount -Each of the two subclasses has different methods (writeCheck for checking, for example) -Both types are created in a main class bank and stored in the same array
So let's say a user goes through the menus and creates a few savingAccounts and a few checkingAccounts (stored in the accounts[] array). Then, to write a check from one account, the user can enter the account number (a string), and the method will use a for loop to cycle through the array until it hits an account number match. Then it checks that it's the correct account type and calls methods from the subclass.
Problem here is that some methods work and some don't. In the following example:
for (BankAccount account: accounts) { if (account.getAccountType().equals("Checking")) { do { if (account.getAccountNumber().equals(accountNumber)) { amount = Double.parseDouble(JOptionPane.showInputDialog(
[Code] .....
The getAccountNumber method works but writeCheck is throwing an error. I tried creating a method in the superclass and overriding it in the subclasses but with no success.
I have an assignment in which I have to design a method where I add an object at any given position in an array and shift the elements already in the array to make room. For example I have a collection class which holds trading card objects. So I wish to add a new trading card to this collection at a specified index or position with out deleting the current object already stored in the array . All this has to be done without the use of array lists, vectors or any abstract data types besides arrays . My question is how do I accomplish this . Say I wish to add a new trading card in position 4 the new card is added to my array and the card currently in position 4 gets moved to position 5 and the card in position 5 gets moved to 6 etc. The maximum amount of cards my collection can hold is 100. How would I add my trading card object to the specified position without overwriting what is currently there and shifting all other elements?Here is my current code.
public class CardCollection { public BaseballCard [] collection; final int MAX_CARDS = 100; public CardCollection() { collection = new BaseballCard[MAX_CARDS]; } public CardCollection(BaseballCard[]c)
[code]...
position refers to the position in the CardCollection and not the position inside the array.
I'm really new to object/class concepts and already having difficulties with applying them. How to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.
Java Code:
public Exam(String firstName, String lastName, int ID, String examType, int score) { this.firstName = firstName; this.lastName = lastName; this.ID = ID; this.examType = examType; this.score = score;
I'm really new to object/class concepts and already having difficulties with applying them. how to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.
public Exam(String firstName, String lastName, int ID, String examType, int score)
The experiments will slowly converge towards one big experiment: a simple game. I have just a little interest in games (perhaps I should have more), but making one - even a simple one - should be self rewarding.
However, now to the point.
* The experiment creates an array of rectangle objects. * The rectangles are painted inside a Frame object at random x,y coords generated by a random number generator * The rectangles are stationary. * The rectangles are each assigned their own random colour. * The array of rectangle objects is created inside the constructor of the class.
The actual code contains various other variables and methods which would distract from a quick analysis, so below is code which has the same logical structure which also fails (instead of array of rectangles, I have used arrays of integers).
import java.util.Random; /** * Experiment 14 - see if it works simply - (with integer arrays) */ public class TestingArrays { // instance variables int N = 10; // the size of the array - 10 elements int[] a;
I hope I'm putting this question in the right folder. I have an array of objects, and I have defined a setter for a variable in the object. When I call the setter, I get a NullPointerException. Here is the relevant code for the object.
public class Digit extends Thread { private int digit; public void setDigit(int digit) { this.digit = digit; } // run method follows }
Here is the portion of the main class where I define an array and then call the setter.
Digit[] digits = new Digit[10]; for (int i = 0; i < digits.length; i++) { digits[i].setDigit(i); // NullPointerException occurs here }
This is what I have to create : Write a method that returns the largest object in an array of objects. The method signature is:
public static Object max(java.lang.Comparable[] a)
All the objects are instances of the java.lang.Comparable interface. The order of the objects in the array is determined using the compareTo method.
Write a test program in the main method that creates an array of ten Strings, an array of ten Integers, and an array of ten java.util.Dates, and finds the largest string (i.e. in the alphabetical order), Integer, and Date in the arrays.
Name your java class Max and your java file Max.java.
I am struggling a bit with this code as I am sure you can see, and am at loss. I have never used the compareTo method. Am I doing this right, or on the right track with my code?
public class Max implements Comparable { public static Object max(java.lang.Comparable[] a) { java.lang.Comparable tempObj = null; for (int i = 0; i < a.length; i++) { if (a[i].compareTo(tempObj) > 0)
Untitled.jpg I have been working over this game lately, and i have managed to render multiple images from an array. in this fashion. I created a Main() class with the following in it:
public Main() { for (int i = 0; i < fuel.length; i++) { Random r = new Random(); changef = r.nextBoolean(); y = (-600 * i) + r.nextInt(300); if (changef) fx = 325; else
[Code]...
Also, this is the Fuel image class and Obstacle image class:
public void tick(Player2 p2) { y += dy; Random r = new Random(); if(x >= p2.getH()) { y = -40 - r.nextInt(700);
[Code]...
(Fuel and obstacle class are identical but separate for better accessibility) I even have player class with an image listening to key events and also a scrolling background. The problem is when i run the game, the images of obstacles render themselves as i want, except for that they overlap each other, i need to prevent over lapping of this images. The fuel is read and obs is black. Heres a glance of how it looks.
Create an application that allows a user to enter values for an array of seven Salesperson objects. Offer the user the choice of displaying the objects in order by either ID number or sales value.
import java.util.*; public class SalesPersonSort { public static void main(String args[]) { int[] id = new int[7]; int[] salesValue = new int[7]; final int END = 999;
Having supplied an interface the question arises as to how it should be implemented. There are a number of possibilities including the use of an array list or a linked list; however it is perfectly possible, and in fact instructive, to begin by implementing PhoneDirectory using a simple array of DirectoryEntry objects. This approach is illustrated below:
public class ArrayPhoneDirectory implements PhoneDirectory { private static final int INIT_CAPACITY = 100; private int capacity = INIT_CAPACITY; // holds telno of directory entries private int size = 0; // Array to contain directory entries
[Code] ......
Develop a tester class called ArrayPhoneDirectoryTester . As usual all methods in the class being tested should be executed at least once by the test driver. Supply standard test documentation - Test Plan, Test Data and Test Log.
In addition to the methods described in the interface the class ArrayPhoneDirectory contains three private methods listed below:
// Searches the array of directory entries for a specific name private int find(String name){}
// Adds a new entry with the given name and telno to the array of // directory entries private void add(String name, String telno){}
// Creates a new array of directory entries with twice the capacity // of the previous one private void reallocate(){}
These methods can be thought of as "helper" methods in that they assist the work of the public methods of the class. For example, the find() method is used by the lookUpEntry() method to locate the position of the a specific directory entry.
Pseudo-code algorithms for the methods of ArrayPhoneDirectory are listed below
Algorithm for load
create a Scanner to read file while (not end of file) use Scanner to read the name use Scanner to read the telno create a DirectoryEntry add the new entry to theDirectory close file
This method is a good place to start coding but note that load makes use of the add method in case the number of entries stored in the text file has exceeded the initial capacity of the directory. So to implement load fully you will need a working version of the "helper" method add. However you can do this in stages by first developing a basic version of add which does not increase the size of the directory. In reading data from the file you may assume that the file only contains matched pairs of names and numbers. There is no need to consider the case of a name not being associated with a telephone number.
Algorithm for addChangeEntry call find to see whether name is in directory if name is in theDirectory change the telno using setNumber return the old telno else add a new entry to theDirectory using method add return null
