Adding Objects To ArrayList
Oct 17, 2014
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?
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Apr 19, 2014
package eg.edu.guc.iphone.tiles;
import java.util.ArrayList;
import eg.edu.guc.iphone.Location;
public class Square extends Piece {
private ArrayList<Location>possibleMoves;
[Code] ......
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Nov 18, 2014
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)
[code]....
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Feb 8, 2015
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)
[Code] ....
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Oct 24, 2014
I am trying to add Point objects into an Array.This is my code to read in data
Java Code:
public void readRoadMap(File road) {
try{
String line;
BufferedReader br = new BufferedReader(new FileReader(road));
while((line = br.readLine()) !=null){
this.points.add(new Point(line));
[code]....
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Mar 15, 2015
I have a ArrayList of objects of class called HockeyPlayer (ArrayList<HockeyPlayer>). A HockeyPlayer has a String name and int number of goals.
This is my current work for comparing each object in the list to every other and printing them to screen:
Iterator<HockeyPlayer> it = hockeyPlayersList.iterator();
while (it.hasNext()) {
HockeyPlayer singleHockeyPlayer = it.next(); //the first one encountered
// HockeyPlayer nextHockeyPlayer = it.next(); //the next one encountered
[Code]...
This of course produces some duplication in the print-out: These are the equal hockey players: Who Ever wears jersey. This type of employee is paid: true. This employee has post-secondary education: false. This employee's work is to play. This hockey player has scored 0 goals.
Jason Harrison wears jersey. This type of employee is paid: true. This employee has post-secondary education: false. This employee's work is to play. This hockey player has scored 0 goals.
These are the equal hockey players: Jason Harrison wears jersey. This type of employee is paid: true. This employee has post-secondary education: false. This employee's work is to play. This hockey player has scored 0 goals.
Who Ever wears jersey. This type of employee is paid: true. This employee has post-secondary education: false. This employee's work is to play. This hockey player has scored 0 goals.
How do I remove the duplication in the print-out?
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Feb 11, 2014
I am trying to access an array of "Movie" objects in my jsp. The array is loaded via
org.springframework.web.servlet.ModelAndView.addObject().
Here is my jsp code:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="security" uri="http://www.springframework.org/security/tags"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
[Code] .....
The System.out.println("jsp page: .... &> results in the output: "jsp page: movielist - [Title: Die Hard; Budget: 20000000, Title: two days in paris; Budget: 1000000]" so I am confident the objects are being loaded into the ModelAndView correctly. However the output of the block is "${movie.name}" instead of the list of movies. My movie object has a getName() method to return a string (and a setName() method). I am not sure why the System.out.println statement can find the movielist attribute, but ${movie.name} is being treated a plain text. There are no execptions thrown or other indications of errors.
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Jun 20, 2014
I want to clone some Arraylist, but the compiler apparently are just referencing the values to it's original ArrayList. I don't know what should it be:
package projetoteste;
import java.util.ArrayList;
import java.util.List;
public class TestFood {
public static void main(String[] args) {
List food=new ArrayList();
[code]....
Notice that ArrayList dailyMeal should be untouchable, but it return the changes that I made in local for-loop iteration although I didn't added nothing to it, just to it's clone.
Output:
[[[Suco, 1 , 2], [Suco, 1 , 2]], [[Suco, 1 , 2], [Suco, 1 , 2]]]
[[[►, ►, Suco, 1 , 2], [►, ►, Suco, 1 , 2]], [[►, ►, Suco, 1 , 2], [►, ►, Suco, 1 , 2]]]
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Mar 23, 2014
Okay, I will be as succinct as possible. I am writing a rudimentary book store program for homework. The program consists of two class files and a main. The main issue I am having is on getting the search portion of my program to work. I will post as little as I can and still make sense. This is the block of code belongs to my public Book getBook() method, which is of the BookStore class.
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Nov 15, 2014
So I am working on an assignment and ran into an annoying bug. Basically i have a menu that accesses an ArrayList of Videos which may or may not be read from a file, one of the options of the menu is to edit an existing Video. For this I ask the user for the number of the video and it is checked against the list of video numbers if it returns a match, the method gets the index of the Video object and stores it in a temporary variable the user is allowed to edit the details and the object is put back into the ArrayList using the variable and the ArrayList's set() method
My problem is that once i finish editing the details of a video it gives me a indexOutOfBounds exception
On further investigation using a method that goes through the index of every object in the ArrayList using indexOf() i found out that every single object has been given the index of -1 and not 0,1,2,3 etc.. This is my first error and have not expierenced any other before.
The objects do exist because I have read them from a file. I can also add new Objects and view them successfully but they still have the same index . I have checked my syntax and everything and no errors, this happens at run time only.
I have even created some other ArrayLists seperately and debugged them and their index order is fine. I am too far into this project to start over. I've also tried cleaning the project(my IDE is Eclipse).
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Jan 23, 2014
I'm having trouble getting new objects to add to an ArrayList. Instead, every time a new object is created and added, it overwrites the first object. So if I read in four lines from a text file and make them into four objects, each overwrites the previous and only the last object is printed. I can print out the contents correctly if I move the println statement within the if-loop; however, I need all the objects to saved to the list for searching (later implementation). i believe it has something to do with the instances of the object, but I'm a little confused about how to fix it. Here's the portion of the code I'm looking at:
Java Code:
if (fileChooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
File file = fileChooser.getSelectedFile();
Scanner scanner = new Scanner(new FileReader(file));
String currentLine;
System.out.printf("%-20s %-20s %-20s
[Code] .....
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Feb 25, 2014
How would you display an ArrayList of Objects in a JSP page from a Servlet. Any general example would be fine as long as the example is thorough.
Each created object has more than maybe 6 or 7 properties that all need to print to the JSP.
Would you also include ways of printing it like should it be printed by using a table structure in the JSP and if so how? Things of that nature so that way it is each object has its own line and looks good. I can format it myself, I just need to know how to get it in a table for each object to print on its own row and so on...
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Jan 9, 2014
I have a problem with my program. My aim is to display in a JPanel, 2 rectangles, and resize them by clicking. I want to give the user the ability to change the height of the rectangles (independently) by moving the top and/or bottom edges. Currently, it displays the 2 rectangles, but impossible to resize and I can not find the solution.
Java Code:
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import javax.swing.*;
public class Resizing extends JPanel {
private static final int PREF_W = 600;
[Code]...
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Sep 11, 2014
So I'm trying to write a method which returns the number of vowel characters in arraylist. My idea is to convert the arraylist element by element to array each time iterating through the array counting the vowels of that element. When I started I immediately got an error(surprise, surprise). Excuse me if the problem is too simple, but I am very new to programming.
At line 9 I get the following error "Type mismatch: cannot convert from String to int". I want to get the element at this position, not to convert to int..
ublic class One {
public static void main(String[] args) {
ArrayList<String> bla = new ArrayList<String>();
bla.add("aaa");
bla.add("brr");
bla.add("unn");
}
public static ArrayList<String> averageVowels (ArrayList<String> list){
String[] arrListWord = list.toArray(new String[list.get(0)]);
return list;
}
}
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Jan 24, 2015
Ive set up a list to when a user creates an element it will be added to the entire list, but when i return to the main menu the Element isnt added.
Here is the code
public void setElement(int atomicNum, Element e){
if (ElementHasData(atomicNum) == false) {
if(atomicNum < MAX){
list[atomicNum] = e;
atomicNum++;
[Code] ...
Here is what the code intiates
~MAIN MENU~
Please select an option you wish to activate
1) Print All Elements
2) Print One Specific Element
3) Add an Element
4) Edit an Element
3
What is the atomic number of the Element you would like to add
Numbers only valid 1-113
1
Enter element name
Hydrogen
Enter element Symbol
H
What is the Elements weight
1.01
NEW ELEMENT ADDED!
[Code] ....
~MAIN MENU~
Please select an option you wish to activate
1) Print All Elements
2) Print One Specific Element
3) Add an Element
4) Edit an Element
But then after i try to print the specific element
~MAIN MENU~
Please select an option you wish to activate
1) Print All Elements
2) Print One Specific Element
3) Add an Element
4) Edit an Element
2
What is the atomic number of the Element
1
that element does not exist would u like to create this element Enter yes or no
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Jan 10, 2014
I have a problem with my program. My aim is to display in a JPanel, 2 rectangles from an arraylist, and resize them by clicking. I want to give the user the ability to change the height of the rectangles (independently) by moving the top and/or bottom edges. There is errors in my code but where ? Netbeans underlines 2 lines (in bold).
My code:
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Path2D;
[Code]....
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Jun 14, 2014
I've come across something that i'm not overall sure about regarding the static keyword in Java.I'm making a vertical scrolling game where the player simply shoots enemies and they shoot back as they fall, dropping items if they die such as power ups and coins. I have an enemy called Bat and this is the bullet creation code in the update method:
if(oldPlayerY + 220 > posY && getBulletDelay > 0.90f){
batBullets.add(new Bullet(posX + 10, posY - 10));
getBulletDelay = 0;
}
The method is creating a new bullet object and it then adds that to the arraylist called batBullets, which is simple enough. I then need to access this arraylist in the main game update class so I can render those bullets on the screen, even if the bat dies. I was always taught that you use the static keyword when you need to access something from the class that doesn't require an object. Because of this, I have the following code.
for(Bullet bullet : Bat.batBullets){
bullet.setY(bullet.getY - 5); // Set the bullet to fall
renderMap.getSpriteBatch().draw(bullet.batBullet(), bullet.getX(), bullet.getY()); // render the bullets
}
This seems perfectly fine to me because I need to access the batBullet arraylist and it doesn't make sense to create a new bat object as I already have random spawning in place for them.
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Nov 27, 2014
Creating an Arraylist and adding item to that array, refer below code
ArrayList<String> sjarr = new ArrayList<String>();
Statement1:
String arritem1 = new String("First array item");
sjarr.add(arritem1);
Statement2:
String num = "text will decide";
sjarr.add(num);
Both adds the String item to array list but puzzling what makes the difference....
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May 5, 2014
I'm having an issues with adding integer values to a string list. The question is asking me "the method should iterate over runners, and for each runner generate a random number between 90 and 180 (inclusive) which should be used to set the time (in minutes) for that runner."
I have been able to get the random number and iterating over the runner arraylist but I haven't been able to figure out how to add the values generated into the runners list. I am also using BlueJ.
Here's the whole code I have at the moment:
import java.util.*;
import java.io.*;
import ou.*;
import java.util.Random;
/**
* Write a description of class MarathonAdmin here.
*/
public class MarathonAdmin {
// instance variables - replace the example below with your own
[Code] .....
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Oct 25, 2014
I managed to retrieve data, and set data in my own ways in which I like. But my problem is, if the file does not contain anything (fully empty), when I try to use my
set("", "");
method, it only sets the last one that is called.
Example:
set("section1", "section1Item");
set("section2", "section2Item");
set("section3", "section3Item");
Only section3 would get set, and not the others.
Otherwise, if the file contained a section already, then each section (section1, section2, section3) would get set.
Here's how I set the data to the file:
public static void set(String section, String data) {
files.openFileWriter();
files.file.delete();
reCreateFile();
String beforeItem = section + ":" + files.dataList.get(section);
if(files.hasReadData) {
[Code] ....
And here is how a retrieve the data and set them to my arraylist/hashmap:
public void getData() {
String line = null;
openFileReader();
StringBuffer sb = new StringBuffer();
[Code] ....
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Jan 23, 2015
I'm trying to fill my jtable with an arraylist. The problem is the jtable is in an extended class and the arraylist in the mainGUI. Now how can I fill the jtable with the arraylist?
That's the arraylist in my MainGUI
BufferedReader in = null;
ArrayList<String> data = new ArrayList<String>();
try {
in = new BufferedReader(new FileReader("1.dat.txt"));
String str;
while ((str = in.readLine()) != null) {
data.add(str);
[Code] ....
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Jun 1, 2014
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.
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Oct 14, 2014
I have a requirement to find the greatest/maximum of the given list of Calendar objects in Java.
i.e., 2013/01/26
2014/03/03
2012/02/27
2014/01/15
So the above list of calendar objects are in Arraylist. I need to get the max/greatest among these. Eventually, the answer should be 2014/03/03
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Mar 18, 2014
I have to create a method with the following header :
public static <E extends Comparable<E> > void sort ( ArrayList<E> list , int left, int right)
i also had to create a swap cells method and position of max integer method. and also had to read the preserved data file in with a scanner. I implemented the comparable interface I am having difficulty sorting my list by the area. It has to be in descending order.
Geometric Object class: since it has comparator also am interested if i need to change this?
CODE:
Driver:
public static void main(String[] args) throws IOException, ClassNotFoundException {
Circle c1 = new Circle (4, "red", false);
Circle c2 = new Circle (2, "blue", true);
Circle c3 = new Circle (10, "blue", true);
Rectangle r1 = new Rectangle (10, 6, "yellow", true);
Rectangle r2 = new Rectangle ( 5, 11, "green", true);
ArrayList <GeometricObject> list = new ArrayList();
[Code] ....
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Nov 4, 2014
I am trying to create a method for my "ticketmachine" object that counts ticket objects in an arraylist of "ticket" objects with a specified field "route". The method works if i change the field type of the ticket class to public, however according to the homework task "route" of the ticket class needs to remain a private field.
Here is my code for the method.
public int countTickets(String route) //HAD TO CHANGE Ticket class FIELD "ROUTE" TO PUBLIC!!!!
{
int index = 0; //returns the number of Ticket objects in the machine with the specified "route".
int ticketCounter = 0;
while (index < tickets.size())
[Code] ....
Is my general approach to the problem wrong? also is there a way to access a private field?
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Jan 13, 2014
I have a code to resize a single rectangle. I would like to display and resize multiple rectangles independently and according to my research on the net, the best way is to use an arraylist. So I modified the code in this sense, except ...when I run the code, the rectangles appear good but impossible to resize. I think the problem comes from mousePressed, Released, Dragged and Moved methods. When I use the mouse to resize the rectangle, nothing happens. The code does not interact with the arraylist, and therefore with rectangles it "contains". Resizing is my main class, the MouseAdapter is in the Resizer class (below).
Resizing component; boolean dragging = false; // Give user some leeway for selections.
final int PROX_DIST = 3; Path2D.Double selectedPath; public Resizer(Resizing rz) {
component = rz; component.addMouseListener(this);
component.addMouseMotionListener(this);
[Code] .....
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