Counts Ticket Objects In ArrayList - Accessing Private Fields
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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May 14, 2015
I came across the below
1) When a variables are declared "Private" How should it be accessed from the driver class ? Sometimes i get an error in driver class saying "your variable is declared Private" why am I getting this error ...
The document says "Private" declared variables should be accessed only through methods. What does that mean.
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Apr 1, 2013
I have this piece of code I wrote a while ago to test something. The issue is accessing a private field of Base class in Base but of a Derived object.
Here is the code:
class Base
{
private int x;
public int getX()
[Code]....
The commented code does not work but casting d to Base does.
Forgot to mention that the compilation error is that x has private access in Base.
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Apr 29, 2014
It isn't messing up it just keeps making me make my arraylist static and i'm not sure why.
public class driver
{
private static ArrayList<AddItems> items;
public driver()
[Code]....
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Jan 30, 2015
Java Code:
import java.util.Scanner;
import java.util.ArrayList;
public class Problem1
{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
ArrayList<String> list = new ArrayList<String>();
[Code] ....
There is an error and says that my ArrayList has private access. I can't figure out how to fix it.
The code runs but when I enter "Quit", the program just stops. The arraylist isn't printed out?
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Mar 17, 2014
I am trying to find a concise way to write the sort methods for my class. I am supposed to make a program that can sort objects by a number of fields: year, rank, artist and title.
I used an idea from this thread : java - Sorting a collection of objects - Stack Overflow
And I am trying to use the custom comparator for my sort methods. However for some reason, the sortingBy variable fails to recognize any of the enum types.
Whenever I try to set the sortingBy variable equal to one of them, for example:
Java Code:
private Order sortingBy = Year; mh_sh_highlight_all('java');
I get a "Year cannot be resolved to a variable" error.
What I want to be able to do is make it so every time a specific method is called, say, for example sortTitle(), sortingBy will change to Title, then the SongComparator will sort using the case Title.
Is it possible to do this? I can't figure out how to modify SongComparator's object variables that way.
Java Code:
import java.util.Comparator;
public class SongComparator implements Comparator<Song> {
public enum Order {Year, Rank, Artist, Title}
public Order sortingBy;
[Code] .....
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Dec 7, 2014
I have GameConsole class with gamePlay(). There are two objects in this class that I want to access from a class in another package.
package blackjackControls;
public class GameConsole {
Player dealer; //both of these objects I am trying to bring over into the blackjackGUI package
Deck playingDeck;
public void gamePlay(){
[code].....
The dealer and playingDeck objects are giving me an error of unresolved. the way it is written I also get a static error on line 37. I know that I have not yet written in the actionEvent statement in the button constructor.
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Sep 19, 2014
Given the class MyExample below:
public class MyExample extends GCompound {
//instance variables
public GRect R1 = new GRect(0, 0, 20, 20);
public GRect R2 = new GRect(0, 0, 5, 5); //R2 is in front of R1, but its coordinates are all "inside" of R1's coordinates
//constructor
public MyExample() {
add(R1);
add(R2);
}
}
1) Suppose I'm in a GraphicsProgram and declare:
MyExample myex = new MyExample();
Suppose I have coordinates (x1, y1), and want to find out whether this is the myex object defined in the previous line. I would use:
obj = getElementAt(x, y);
if (obj == myex) (...and so on)
Now suppose I want to test whether the object is the GRect object R1 within myex. Why doesn't the following work?
if(obj ==myex.R1) (...and so on);
Here is the full code that shows my question; it outputs "myex", none of the other outputs come out...
public void run() {
GObject obj1, obj2;
MyExample myex = new MyExample();
add(myex);
obj1 = getElementAt(1, 1);
obj2 = getElementAt(19, 19);
if (obj1 == myex) System.out.println("myex");
if(obj1 == myex.R1) System.out.println("R1");
if(obj1 == myex.R2) System.out.println("R2");
if(obj2 == myex.R1) System.out.println("R11");
if(obj2 == myex.R2) System.out.println("R22");
}
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Oct 19, 2014
What I want to do is this, this is my first class:
public class Footballer {
int goals;
String surname= "";
String team="";
private static int counter=0;
private int dres;
}
(this is just the header of the class... And this is my second class, which contains an ArrayList of the first class:
public class FootballTeam{
String teamname="";
String league="";
ArrayList<Footballer> f;
}
And this is my third class which contains an ArrayList of the second class:
public class FootballLeague{
String leaguename="";
ArrayList<FootballTeam> ft;
}
What I want to do is, know how many of footballers are there in the league? Meaning how many of "f"s are in the "ft"... I remember from C++ it was easy, you just did it something like this: ft.f[i]; (where i is a position), then you'd go through each of them, if you wanted to do something with them, or just ask for it's length, if you needed to know how much footballers are there.
I'm trying this method to get the size of the array in the 2nd class, from the 3rd class (containing an ArrayList of classes of 2nd class, but no luck:
int counter=0;
for(int i=0;i<this.ft.size();i++) {
counter+=this.ft[i].f.size();
}
I'm getting this: Array required, but ArrayList<FootballTeam> found ---
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Nov 27, 2014
I'm a total newbie to Java, and until now all I've done was draw some shapes and flags. I'm struggling to understand the code I've been given. I need to access values stored in an ArrayList within another class. Here are the two classes Seat and Mandate:
package wtf2;
import java.util.*;
public class Seat {
public int index;
public String place;
public int electorate;
[Code] ....
The main class contains code that feeds data from 2 text files into Seat and Mandate. From there I managed to access the date in Seat (at the end):
package wtf2;
import java.io.*;
import java.util.*;
public class CW2 {
public static void main(String[] args)throws Exception {
[Code] ....
Now,instead of getting just the mp for Edinburgh South I need to get the vote values, compare them to each other, take the second biggest and display the associate party value. How to access data from that Array to get started at least.
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Oct 19, 2014
What I want to do is this, this is my first class:
Java Code:
public class Footballer {
int goals;
String surname= "";
String team="";
private static int counter=0;
private int dres;
} mh_sh_highlight_all('java');
(this is just the header of the class, just how it looks)...
And this is my second class, which contains an ArrayList of the first class:
Java Code:
public class FootballTeam{
String teamname="";
String league="";
ArrayList<Footballer> f;
} mh_sh_highlight_all('java');
And this is my third class which contains an ArrayList of the second clas:
Java Code: public class FootballLeague{
String leaguename="";
ArrayList<FootballTeam> ft;
} mh_sh_highlight_all('java');
What I want to do is, know how many of footballers are there in the league? Meaning how many of "f"s are in the "ft"... I remember from C++ it was easy, you just did it something like this: ft.f[i]; (where i is a position), then you'd go through each of them, if you wanted to do something with them, or just ask for it's length, if you needed to know how much footballers are there.
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Oct 14, 2014
Scanner in = new Scanner(System.in);
ArrayList<rand> selectedRand = new ArrayList<Rand>();
selectedRand.add(new Rand(in.nextLine()));
I have created the most minimal code for creating an array list. I was wondering what the basic syntax of accessing objects methods that are within an Array List. So if I was to trying and get a method such as [.returnValue,] how would this look within a Rand object that is declared in a Array List Since you cannot simply declare a new Rand object and say:
newRandObject.returnValue();
And you must go through the actual slotted portion of the array list. I have searched the web and my text book for an example however none are provided.
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Dec 10, 2014
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
[Code] .....
This is the error message:
----jGRASP exec: java ItemRecordReport
Item Cost Quantity Description
Number
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
Exception in thread "main" java.lang.NullPointerException
at ItemRecordReport.main(ItemRecordReport.java:161)
----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
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Mar 4, 2014
I have a data structure such as: ArrayList<ArrayList<Integer,String>
The data looks as [[1,2,3] [3,4] [99,98,40,32,45,65,1]]
I am trying to access each element and put them into a hashtable such as:
Hashtable<Integer,String>
With what I am doing below I am getting an out of bound error but can't see any other way of accessing the element
public static void hash(ArrayList<ArrayList<String>> list)
{
for(int i = 0; i < list.size(); i++)
{
int cnt = 0;
for(int y = 0; y < list.size(); y++)
{
if (! hashMap.containsValue(list.get(i).get(y)))
{
hashMap.put(cnt, list.get(i).get(y));
cnt++;
}
...
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May 27, 2014
I have been working on this function and i can't get it to work. It's a little bit complicated so let me first explain what this is about:
1. As a little exam in my studies i have to program a halma console game with KI an stuff.
2. Everything is finished and works except for the Move-Calculation.
3. A Move is a Move from Field a to Field b which a player can perform in one round based on the game rules (Careful: We are not using the standard halma rules, we use different ones).
4. Class Move consists of the Starting Cell where the Figure before the Move stands and a target Cell where the figure will stay on at the Move end. It may include an Array of serveral Cells, the stop cells which the figure passes from start -> target since several jumps can be performed in one Move.
Valid Examples for Moves:
a -> b (From Field a to Field b)
d -> f through g,h,i (From Field d to Field f through the Field g,h,i
My Move Calculation where all possible Moves are calculated for a given figure consists of 2 parts. An expand() function which will generate all possible moves (works perfectly) and a jumpFix() function which isn't working properly.
Example:
After expand() I'm getting something like that:
a -> b
b -> c
c -> d
s -> t
This is however not finished, because the first 3 Moves are actually 1 Move. Because the player can Move from a -> d in one turn because those 3 are consecutive Move. The fixed Move would look like that:
a -> d through b,c
jumpFix() is also perfectly working for that situation, however there is one specific situation when it doesn't work. Let's say we have this situation.
a -> b
b -> c
c -> d
b -> e
e -> f
f -> g
s -> t
Then the only valid jumpFix() output would be:
a -> d through b,c
a -> g through b,e,f
s -> t
However i can not get it to work yet. Note: It definitely needs to be iterative, not rekursive else i would get an StackoverflowError.
This is my current Code of jumpFix():
Java Code:
/**
* Takes a look into all calculated moves and finds those which should be seen as one move, but are still considered to be more than one move (several jumps in one move)
*/
public static List<Move> jumpFix(List<Move> moves) {
Set<Move> result = new HashSet<Move>();
Set<Move> remove = new HashSet<Move>();
int lastSize = -1;
// repeat action until no moves could be merged
while (lastSize != remove.size()) {
[Code] ....
How to implement the special case where a Move splits into 2 or more branches and jumpFix() able to handle this case.
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Feb 24, 2014
I've tried a couple ways to do it, and they don't work. I'm aiming for functionality like I got with the regular for loop, but from an enhanced for loop. Is this simply beyond the scope of an enhanced for loop, or am I just not getting the right syntax?
TestObject to1 = new TestObject("first", 11);
TestObject to2 = new TestObject("second", 12);
TestObject to3 = new TestObject("third", 13);
TestObject to4 = new TestObject("fourth", 14);
TestObject to5 = new TestObject();
List<TestObject> testList;
testList = new ArrayList<TestObject>();
[code]....
The TestObject class is simply an int and a String, with getters getInt and getString. It all works fine with the regular for loop.
edit: I should probably mention that I know what I have in the enhanced for loop now will only display the class name and the hash. I've tried adding the .getString and .getInt, and tried a few other ways to make it work. I just reverted to this because it compiles and runs
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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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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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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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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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