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 have to read in a file that that has Student, Employee, Faculty....such as name, last name, salary...etc
Example of a file input Java Code: Student, John, Doe, [email]johnDoe[At]yahoo.com[/email], 123,Wonderland Ave, 21323,TX PhoneNumber,Cell,111,222,3333 Student, Jesus,Satan,[email]jesus[At]satan.com[/email,666, HeavenHell Dr., 666666,CA PhoneNumber,Work,111,333,5555 mh_sh_highlight_all('java'); Java Code: while(input.hasNext()){
[code]...
There is more code, but it's repetitive. Now, I keep getting an error. Array of bounds. I believe i get the error because the phone number. The phone number is on the next line..I created a different arraylist for phonenumber, but I dont know how to match it with the correct person, student, employee...etc.
I need to be able to call this method and it should take the object and, add it to my list of items, but I am having trouble getting it to work. I know the numbers and stuff aren't correct eventually it will add one to the array length when i call add item, but I am just trying to go one step at a time
//creates new MediaItem object and add it to items[] void addNewItem(String title){ MediaItem object = new MediaItem(title); MediaItem[] items = new MediaItem[1]; items[0] = ("object.getTitle()"); numberOfItems = numberOfItems + 1; System.out.println(items[0]);
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)
I've two classes: Student and ArrayListExamples (which has my main method in it).
The student class acts pretty simply at the moment with a constructor that takes a name, surname and ID number. I've tested it and it seems to be working. My issue is with adding an object to an array list, here is my effort:
public class ArrayListExamples { private static int MAX_SIZE = 50; static Scanner sc = new Scanner(System.in); public static void main(String[] args) { ArrayList<Student> students = new ArrayList();
[code]....
I know the last loop to add the student objects is wrong.I'm calling the student ArrayList add method with a student object whose constructor requires two strings and an integer. Why isn't this allowed?
Having trouble adding Class (Dollar) objects to a HashSet (money), i have done this before with arraylists and i understand that HashSets are different in that they cannot contain duplicates. Currently when this code is compiled i am getting "null" printed when I run the "howFullDatWallet" method.
import java.util.*; public class Wallet { private HashSet<Dollar> money; private int walletSize = 0; private int walletFiller = 0; /** * Constructor for objects of class Pocket */ public Pocket(int walletCap)
I am making a graph to implement Breadth First Search and Depth First Search. I changed the program because I want each button to be its own node. However I am having an issue placing them into a panel. When I run the program I get the following error:
The method add (Component) in the type Container is not applicable for the arguments (Buttons)
JPanel matrixPan(){ Buttons[][] matrixBtn = new Buttons[25][25]; JPanel panel = new JPanel(); panel.setSize(550,550); panel.setLayout(new GridLayout(25,25));
I decided to write a small Java program to experiment around with BorderLayout, because I'm developing a Java game and I need to have 2 objects placed in a single JFrame at the same time, and everyone I asked said I need BorderLayout to do that.Before you answer: Also, is using BorderLayout the best option for adding multiple video game oriented objects such a sprites to a JFrame?
So the Java program I wrote is supposed to place a JButton on the JFrame and ALSO place a graphic component (a rectangle in this case). The problem is, only the button shows up, as can be seen in the image link below: URL....
Here is the code:
**main.java** --> The main method class + JFrame/JPanel/JButton constructor import java.awt.BorderLayout; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; public class main {
We are doing a Timeline project, So this is what i want to do:
Pressing a "New Event" button opens the New event window where you are supposed to write input in three fields, name, date, and information. There is also a button "Create" that when i press that button, i want to take all the input from the fields and save/send it to our database, and go back to the timeline GUI. With this, i want a new event object to be created(in this case i have done several shapes in a group) so basically a new group i want to be added. All the information is suppose to be taken from the database right after i create it.
I'm pretty stuck on how i should solve this, for the moment have a group called event that i add on the canvas. First thing that pops up in my head is a void method that draws the event, or maybe a temporary array.. P
When I try to print out the account Id for each account object, the id is always 1. But it should be 1,2,3,4,5....all the way to the number of the account generated.My question is am I missing something in the constructor or in the main method?? I am new to programming.The main method create an array of account objects and generate random balances into each account object.
import java.util.Scanner; public class Bank { public static void main(String[] args) { Scanner userInput=new Scanner(System.in); System.out.print("Enter the number of accounts to generate: "); int numOfAccount=userInput.nextInt();
I have a program I am creating in Eclipse. In my JFrame window, I am adding a JList object that I want to load with an EnumMap that I have created in a separate 'enum' class.
In my JFrame, I have a method called 'loadJList()' in which I want to iterate through the EnumMap and load the keys & values.
Here's what I've tried
In my EnumMap class, I've done the following ...
Java Code:
public enum MyEnumMap { .....//created map values & keys, getter() and setter() public Enum<MyEnumMap> getEnum() { return this; } } mh_sh_highlight_all('java');
I imported my EnumMap program in my JFrame program and tried something like ...
Which does not work. I've scoured the internet a bit but sources on EnumMap are limited, at least ones I can understand (first time trying to use this).
I also need to elaborate on the key of the EnumMap (they are cities, I'd like to add the state or country). For example
LASVEGAS, 749.99
I would want displayed as
Las Vegas, Nevada .... 749.99
My ultimate goal here is to access my EnumMap in my JFrame program to dynamically load a JList object.
Say I have two classes, Author and Book, and I have 2 author objects and 10 book objects. I would like to know how to do two things:
1) Make some sort of connection that makes clear that author X wrote books A, B and F. 2) Call a method from a book object that is connected to an author.
Seeing as I don't know which books will be connected to an author, is there some way to call a method of an object bases on a variable object name? Something like call the getFirstPage() method for every book that is linked to author X?
I have a project in java that asks me to load some information from previous object files and add new objects to them afterwards. I created the files, but when I close the program and search for the previous information that should've been saved in the object file , it return nothing.
Here is the code.
Add method:
public boolean addUser (User u){ users[Ucount]=u; Ucount++; return true; }
The save method:
public void saveUser (){ try{ FileOutputStream FOS = new FileOutputStream("User.txt", true); ObjectOutputStream OOS = new ObjectOutputStream (FOS);
[Code] ....
The read method:
public void readUser (){ try{ FileInputStream FIS = new FileInputStream ("User.txt"); ObjectInputStream OIS = new ObjectInputStream (FIS); for (int i=0;i<Ucount;i++){
[Code] ....
*Note: When I open the object file I could see that the information are actually there, so I think there's a problem with the read method I'm not sure what it is.
In a project I'm ivolved in I have to dynamically add some components. All was going well until I had to generate data tables dynamically. I'm iterating a list of "SomeObject" and when I try to access a property of that object Glassfish tells me that object doesn't have such a property that is readable. I have getters for those properties and SomeObject implements Serializable as well. I used BalusC resources but I'm having no luck.
This program is basically complete. It compiles and runs. It is a college course assignment that I pretty much completed but for the last part in which I'm suppose to change the values of all fields and display the modified values using a toString method. Modifying the values of the fields is where I am stuck. I don't think I need to create a new text data file to do this. The instructor only asked that all the values of fields be changed and this was the last part of the assignment so I don't think it involves creating additional ObjectOutputStream and ObjectInputStream objects. I'm getting a NullPointerException error on line 161.Here is the code. I'm also including the input data file.
//create program so that objects of class can be serialized, implements interface Serialiable //create constructor with 4 parameters with accompanying get and set methods, Override toString method //create text file with 5 records, create Scanner object,ObjectOutputStream, and ObjectInputStream //create new ItemRecord object, change values of all fields in ItemRecord object using object's set methods //modify ItemRecord object using toString method
[hightlight =Java]import java.io.Serializable; public class ItemRecord implements Serializable
----jGRASP wedge2: exit code for process is 1. ----jGRASP: operation complete.
Here is the data file: A100 99.99 10 Canon PowerShot-135 A200 149.99 50 Panasonic-Lumix T55 A300 349.99 20 Nikon- D3200 DSRL A400 280.99 30 Sony- DSC-W800 A500 97.99 20 Samsung- WB35F
Here is the data file for the modified field values. B100 98.00 10 ABC1010 B200 97.00 15 DEF1020 B300 96.00 10 GHI1030 B400 95.00 05 JKL1040 B500 94.00 01 MNO1050
I am working on a text based adventure game. (This is NOT OOP at all) The problem comes in at my second if statement inside my loop, it is not adding 1 to my array locations[] it keep printing location[0] then a 1 at the end. Not really sure what is going on here. I would like it to when I type "Go north" it adds 1 to locations[]
E.G locations[0] Go north locations[1] go north locations[2] package com.PenguinGaming; import java.util.Scanner; public class Game{
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.
public class Main { public static void main(String[] args) { Player[] playerList = new Player[] {new Player("Daniel", 3, 3, 2, 1, 1, 3),new Player ("Player2", 2, 4, 1, 6, 3, 2)}; System.out.println(Player.getPlayer()); } } mh_sh_highlight_all('java');
[code]....
and whenever I run it, it prints out the last player, so I was wondering how to identify them separately, but still use the array, as (I believe) it is the most efficient way.
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()};
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.
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?
I am working on a assignment that has to do with array lists, it mainly has to do with adding new elements, telling then where it is it located, if the memory block is empty , ect. so far i have been having problems with my indexOf method which should display the array cell number that a input element E is in, and if it is not in there it should display a -1.
public class MyArrayList<E> { private E[] data_store = (E[])new Object[2]; private int sizeofa = 0; private void resize()// makes the array list bigger if need { E[] bigspacemaker = (E[])new Object[data_store.length * 2]; for(int x = 0 ; x< sizeofa ; x++)
[Code] ....
Error message: Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 512 at MyArrayList.indexOf(MyArrayList.java:28) at MyArrayListDemo1.main(MyArrayListDemo1.java:26)
