Changing Canvas Returns With NullPointerException
Jun 21, 2014
I'm currently having trouble with a Breakout clone that I'm working on when I want to change the scenes of the game. When I start out with the main menu and I hit play, the main menu calls for the StateManager to remove the MainMenu and then to add the GameState to start playing through the levels. But, whenever this is done it just gives a NullPointerException and freezes the game. I know the code for initially starting a State is fine because that is the same way the MainMenu is loaded but there seems to be an issue with changing from one to another...
This is the StateManager class that adds and removes the States/Canvases to and from the JFrame/Main class:
public class StateManager
{
private ArrayList<State> states;
private int currentState;
private JFrame gameFrame;
public StateManager(JFrame gameFrame)
{
this.gameFrame = gameFrame;
states = new ArrayList<State>();
[Code] ....
I've tried messing around with the order of which things are added/loading from the StateManager but am just failing to see what I did wrong.
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Jun 22, 2014
I'm currently having trouble with a Breakout clone that I'm working on when I want to change the scenes of the game. When I start out with the main menu and I hit play, the main menu calls for the StateManager to remove the MainMenu and then to add the GameState to start playing through the levels. But, whenever this is done it just gives a NullPointerException and freezes the game. I know the code for initially starting a State is fine because that is the same way the MainMenu is loaded but there seems to be an issue with changing from one to another...
This is the StateManager class that adds and removes the States/Canvases to and from the JFrame/Main class:
package com.pathtocreating.Breakout_V2.state;
import java.awt.BorderLayout;
import java.util.ArrayList;
import javax.swing.JFrame;
public class StateManager {
private ArrayList<State> states;
[Code] ....
The code that calls the change of state in MainMenuState is called in the update method:
if(inputController.isMouseClicked("LeftClick")) {
if(playHover) {
soundManager.playSound("ButtonClick");
BreakoutMain.sm.changeStates("GameState");
[Code] ....
Here is the full stack trace when clicking the area to change states:
Exception in thread "Thread-2" java.lang.NullPointerException
at sun.java2d.SunGraphics2D.validateColor(Unknown Source)
at sun.java2d.SunGraphics2D.<init>(Unknown Source)
at sun.awt.image.SunVolatileImage.createGraphics(Unknown Source)
[Code] ...
It gives that same value both before and after clicking on the region.
Printing out b after the State is changed to GameState gives the following:
java.awt.Component$BltSubRegionBufferStrategy@66116674
I've tried messing around with the order of which things are added/loading from the StateManager but am just failing to see what I did wrong.
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Feb 23, 2013
I am doing this
@Startup
@Singleton
@ConcurrencyManagement(ConcurrencyManagementType.CONTAINER)
@Lock(LockType.READ)
public class ResourceBean {
[Code] ....
And I call this singleton bean from a stateless session bean like this
@Stateless
public class ClientBean {
@EJB
ResourceBean resource;
public String create(String r)
{
String res=resource.returnString(r);
return res;
}
}
But resource.returnString(r); gives a org.apache.jasper.JasperException: java.lang.NullPointerException I started the glassfish server in debug mode and found out that "resource" was null. but @PostConstruct in singleton does print which means singleton bean exists.
Can we call singleton beans with no interface in such a way form a session bean? I actually want to acquire instance of singleton bean when a client invokes method in Client bean...
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May 5, 2015
I have to build a simulated OS for my college class. I'm making it pretty simple, nothing too fancy and am using HTML5 Canvas. So far I have the icons on a black background and have made them draggable. I want to know how I can make it so when you click on an icon a box appears (just like a real OS) and then closes by clicking on the 'x'. I also want to be able to drag any icon into the trash bin and it disappears. I understand there are click/mouse events, but I don't know how to implement them into the code I have setup. Here's the code:
<!DOCTYPE HTML>
<html>
<head>
</head>
<body>
<div id="canvas"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/kineticjs/5.2.0/kinetic.js"></script>
<script defer="defer">
var stage = new Kinetic.Stage({
container: 'canvas',
width: 1910,
height: 995,
[Code] ....
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Apr 10, 2014
Java Code:
public class Game extends Canvas implements Runnable, KeyListener {
private static final long serialVersionUID = 1L;
public Game() {
setMinimumSize(new Dimension(width, height));
setMaximumSize(new Dimension(width, height));
setPreferredSize(new Dimension(width, height));
}
[code]...
I want to remove the extends Canvas from the top line and when I use JFrame to add canvas, I don't do add.(this, but instead I do add a canvas variable I make. So instead of extending I want to make a variable. But then how would I do the start, stop and run?I want to use Graphics, Canvas (Not Jpanel because I want to use BufferedImage) & JFrame. I don't want to extend Canvas, how could I use Canvas identically to shown above but instead of extending using it as a variable? or, how could I do this?
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Feb 25, 2015
I want to create off-screen images by Canvases in multi-thread environment.
I know that I use methods of GraphicsContext2D to draw on Canvas. Can I do this on Canvas which is not added to Scene ?
How can I get an image from a canvas after I invoke GraphicsContext2D methods? Can I get images in multi-thread environment ?
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Apr 21, 2015
I am doing a project for my Java class but I ran into a snag with my code.
package lesson13;
import java.io.FileNotFoundException;
import java.util.LinkedHashSet;
import java.util.Set;
public class CharCountingStudy {
public static void main(String[] args) throws FileNotFoundException{
Set<FileExaminer> examiners = new LinkedHashSet<>();
examiners.add(new FileExaminer("raven.txt"));
examiners.add(new FileExaminer("jabberwocky.txt"));
[Code] ....
I keep getting a NullPointerException at the "examiners.add(new FileExaminer("raven.txt"));", the "calculateCharCountAlpha();", and the "if (charCountAlpha.containsKey(w)){"and I don't know why it is doing that.
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Oct 23, 2014
I am getting a NullPointerException Error and I cannot seem to figure out what is causing it. I am reading in a grades1.dat text file and putting the values into a 2D array. The error is occuring in my addGrade method, but I am not sure what the error is. Here are the values for my grades1.dat that I am running in through Run Arguments in JGRASP.
Student1
5
a Activities 0.05
q Quizzes 0.10
p Projects 0.25
e Exams 0.30
f Final 0.30
a100 a95 a100 a100 a100
q90 q80 q100 q80 q80 r90
p100 p95 p100 p85 p100
e77.5 e88
f92
Here are the errors that I am getting.
Exception in thread "main" java.lang.NullPointerException
at GradeBook.addGrade(GradeBook.java:114)
at GradeBookApp.main(GradeBookApp.java:55)
import java.util.Arrays;
/**
* Stores students name, a char array of category codes, a String array of categories, a double array of category weights, and a two dimensional double array of grades where each row contains all the grades in a particular category.
[code]....
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May 3, 2014
I have been playing around with my code, but how to avoid NullPointerexception.. So my program's point is simple, use Jsoup to scrape html of certain webpage, then i search the things i want and print them out. Problem is, when scraped html doesnt contain even 1 thing on my search list, i get NullPointerException... i understand why, Heres part of my code:
Java Code:
//Things i need to search from html
String[] MySearchArray = new String[]{"138","146","474"};
//Search things contained in MySearchArray and print them out
for (String Ml : MySearchArray) {
Element flights = doc.select(String.format("tr:contains(%s)", Ml)).first();
Elements flights2 = flights.select("td");
System.out.println(flights2.get(4).text() + " " + flights2.get(0).text()+ " " + flights2.get(3).text());
} mh_sh_highlight_all('java');
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Feb 10, 2015
/**
* This method displays all winner names for a given year.
* @param year is the integer parameter asked of the user.
*/
public void displayAllWinnersForYear (int year) {
if (year >= 1993 || year <= 2009) {
String[] winnersForTheYear = nobelPrizeWinners.get(year);
for (int i = 0; i < winnersForTheYear.length; i++) {
[Code] ....
When year is outside the 1993-2009 range, I get a NullPointerException from line 10. Shouldn't it be skipped entirely since the conditions of its parent IF statement (line 7) is not met?
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Mar 18, 2014
Am new to programming and am trying to create a system that is similar to a train timetable system.I want the user to be able to enter the stops between two stations ( from a preset list of 5 stations ) and this be saved as an array list, and this array list be saved accordingly within a 2D array so if they were to look in [1][2] there would be an arraylist of stops between station 1 and 2.I used this to initialise the array of arraylists (in a class i created called stops)
ArrayList<String>[][] stopsArray= (ArrayList<String>[][])new ArrayList[5][5];
public void stops(){
for (int i = 0; i<5; i++){
for (int j=0; j<5; j++){
stopsArray[i][j]= new ArrayList<String>();
}
}
}
Then I use this code to set the stops
public void setNoStops(int stopsNo){
noOfStops = stopsNo;
}
[code]...
The bottom written line of code is mentioned in the null pointer error I recieve. Then.Then in my main programme I declare the new object and use these methods the method options displays the list of five stations with a number reference
System.out.println("Please choose a start station :");
options();
place1 = scanner.nextInt();
System.out.println();
System.out.println("Please choose an end station :");
options();
place2 = scanner.nextInt();
System.out.println();
[code]...
mystops is the object I created to store the information.
when compiling I recieve no errors.when I run the program it runs smoothly, asks for the number of stops, allows the user to enter a number, then says enter stop 1, I enter a word and the program crashes giving the error java.lang.NullPointerException
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Mar 1, 2014
I am having some problems with some code and I need an extra set of eyes. It appears I've missed something. I am getting a NullPointerException with a Hashtable object, which I can clearly see I've created. So I'm not quite sure why it is happening. I am pretty sure it is do with the code I've posted because I've tested everything else involved.Here is the code where it happens,
Java Code:
public void siteGen(String user, String site)
throws ExcGenDatabad, ExcSiteNodomain, Exception {
System.out.println("calling siteGen, user: " + user + ", site: " + site);
String nginx_template;
String fpm_template;
[code]....
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Aug 26, 2014
I'm new to web services. Right now i'm trying to consume JAX-WS web service on IBM WebSphere Application Server 7. Sending SOAP message with security header[username, password] parameters. Getting NullPointerException..
Exception :
javax.xml.ws.WebServiceException: java.lang.NullPointerException
at org.apache.axis2.jaxws.ExceptionFactory.createWebServiceException(ExceptionFactory.java:175)
at org.apache.axis2.jaxws.ExceptionFactory.makeWebServiceException(ExceptionFactory.java:70)
at org.apache.axis2.jaxws.ExceptionFactory.makeWebServiceException(ExceptionFactory.java:128)
at org.apache.axis2.jaxws.marshaller.impl.alt.DocLitBareMinimalMethod
Marshaller.demarshalFaultResponse(DocLitBareMinimalMethodMarshaller.java:443)
at org.apache.axis2.jaxws.client.proxy.JAXWSProxyHandler.getFaultResponse(JAXWSProxyHandler.java:559)
at org.apache.axis2.jaxws.client.proxy.JAXWSProxyHandler.createResponse(JAXWSProxyHandler.java:497)
at org.apache.axis2.jaxws.client.proxy.JAXWSProxyHandler.invokeSEIMethod(JAXWSProxyHandler.java:404)
[code]....
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Dec 10, 2014
I recently switched some of code around to restructure how some things were working but now when I run the program I am getting a NullPointerException in multiple areas. I suspect it may have something to do with a constructor. I am very new to "object" - ish based programming.
I figured I should give a little background on the program, this program is reading from a text file of names and decade numbers(for each name) and storing each line into an object array. From there, there are menus and based on the users decision they can type a name and get a histogram, compare names with histograms, ect. Below this main method, I have provided the area where I have gotten the null pointer exception.
Here is the main method for the Client "nameApp"
Also excuse the formatting and curly braces for now!
public class NameApp{
private static boolean validInput;
private static boolean done = false;
private static boolean validDecade;
private static boolean validName;
[Code] ....
And here is the method in the same Client that is getting the null pointer exception:
The pointer exception is on line 6 which is:
if (nameInput.equalsIgnoreCase(list[i].getName())){
private static int checkListArray(String nameInput, Name[] list){
int nameLocation = -1;
int listLength = list.length;
[Code] ....
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Nov 7, 2014
I have an arraylist, list, that I need to take the size to declare an array, arr3, in another class. Problem 1: the size is giving me an error of "can not make static reference to non-static method getListSize() from the type FindItemInfo". I tried to change getListSize() to static and it gives me and error another place. I try to then fix that, and I get a new error... and so on.
I am using arr3 to store items the user can not afford. I have this next problem even when I input an integer for the arr3 size. I am getting a NullPointerException, and I can't figure out why the arr3[] is not loading. I tried debugging but can not figure out where I went wrong, especially since this code was working in the last assignment before I changed list[] to an arrayList. It always breaks at line 64, but I believe it has to be somewhere in the cashOut() method.
Relevant code is:
public class FindItemInfo implements InterfacePrint{
ArrayList <ItemAttribute> list = new ArrayList<ItemAttribute>();
//does stuff
public void printPriority(){
TransactionCalc finish = new TransactionCalc();
[Code] .....
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Nov 20, 2014
I have a swing application that is using JFileChooser. When I click the Open menu item from File menu it should show the File dialog box where user can select the file.This application is running in my machine but encounters problem in another machine. File dialog box is not showing and stack trace shows that NullPointerException is thrown by JFileChooser..My machine is a 64 bit Windows 7 while the other machine is Windows 7 32 bit. Both machine are using java 1.6..To verify if its because of the 32-bit, I tried in another Windows 7 32-bit and the same application is working.
I came across this article [URL] .... which identified it as bug but already fix in 1.4.2_04. Though I am using 1.6, just to make sure I also tried the suggested work around.I put System.setProperty("swing.disableFileChooserSpeedFix", "true"); in my code but still not working...I also tried to add java -Dswing.disableFileChooserSpeedFix=true to the batch file that is launching the application and still not working
Code Sample:
import javax.swing.JFileChooser;
import javax.swing.filechooser.FileNameExtensionFilter;
public class FileChooserTester{
public Boolean loadMDBFile() {
System.setProperty("swing.disableFileChooserSpeedFix", "true");
JFileChooser fc = new JFileChooser();
[code]...
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May 18, 2013
I have a little a problem with String object in this class ....
public class Personne {
private String nom;
private String prenom;
private int age;
public Personne(){
this(null, null, 0);
[Code] ....
When i call the class personne with the Personne() i get these errors in compiling-time :
Exception in thread "main" java.lang.NullPointerException
at java.lang.String.<init>(Unknown Source)
at Personne.setNom(Personne.java:18)
at Personne.<init>(Personne.java:12)
at Personne.<init>(Personne.java:8)
at Main.main(Main.java:4) // The line wich i inisialize my object in my main method.
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Jun 17, 2014
I tried to print something using the new JavaFX 8 printing logic. Unfortunately, it does not work.
System:
Linux Mint 17x64
Oracle JDK 8u5
Default printer is cups pdf
Code:
package sample;
import javafx.fxml.FXML;
import javafx.print.PrinterJob;
import javafx.scene.control.TextField;
[Code].....
Debugging shows the array MediaPrintableArea[] mpa at J2DPrinter:839 is missing its first element, which causes the exception at line 844.
If I execute
service.getSupportedAttributeValues(MediaPrintableArea.class, null, null)
instead of
service.getSupportedAttributeValues(MediaPrintableArea.class, null, pras)
I get an array with an element on the first position.
The msn object used for the PrintRequestAttributeSet is "iso-a4", which causes the missing first element in the MediaPrintableArea[] array.
So why does this happen? Am I missing some important config stuff? I tried to fix it myself, but I am not able to debug service.getSupportedAttributeValues(...).
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Oct 4, 2014
Iva tried flipping the entire code upside down (expression) and No matter what I do the delete function returns a null pointer exception after my while loops takes the pointer right to where it should be.
package bp;
import java.time.LocalDate;
public class BinaryTree implements IBinaryTree {
private Node root = null;
private int sizeOfTree = 0;
[Code] ....
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Nov 21, 2013
I'm new to JSP but I've to use it to grab data coming from an external site, pass data to a Bean, write data in a DB and redirect the user to another page. Follow the JSP page.
<%@page import="EJB.getResponse"%>
<%
long paymentID = Long.parseLong(request.getParameter("paymentid"));
String responsecode = "9999";
getResponse g = new getResponse();
[Code] ....
This is the bean:
@ManagedBean
@RequestScoped
public class getResponse implements Serializable {
private Long paymentId;
private String result;
private String auth;
[Code] ....
On the console I see the prints but I receive the NullPointerException
WARNING: StandardWrapperValve[jsp]: PWC1406: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at EJB.getResponse.printData(getResponse.java:72)
at org.apache.jsp.notify_jsp._jspService(notify_jsp.java from :60)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
[Code] ....
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May 28, 2014
this program works but returns zero for all the calculations. I checked everything there is no error but I dont know why is returning 0.
package mshproject3;
import java.util.StringTokenizer;
import javax.swing.JOptionPane;
public class HayloFactoryController {
public static void main(String[] args) {
String firstName = "";
String lastName = "";
String phoneNumber = "";
int aNbrOfVehicles = 0;
int aNbrOfFuelTanks = 0;
HayloFactory factory;
[code]....
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Oct 21, 2014
I have a routine that returns a boolean. If any of a series of tests fails, the routine returns false, otherwise it returns true. For example, the routine might test for whether or not an integer is both odd and greater than 99, thus:
public boolean oddAndOld(int x)
{
if (x % 2 == 0)
return false;
if (x < 100)
return false;
return true;
}
I like the above because it suggests that "true" is the condition that applies if the incoming parameter meets all the required criteria. But I've sometimes seen this style used:
public boolean oddAndOld(int x)
{
if (x % 2 == 0)
return false;
if (x < 100)
return false;
else
return true;
}
I like this less because, among other things, if that last criterion is removed, the "else/return true" must be moved up into the immediately preceding test (or else leave some funny whitespace, depending on how you go about removing the departing "if" statement), but it does avoid suggesting that "return true" is hard-coded (that is, it reinforces that "true" is a conditional return value, not inevitable).
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Jan 26, 2015
I've been trying to make a class that has a toString method that displays the board at the same time displays the value of each index of a 2d character array inside of the code. My professor has made the client print the method. I assumed since he was printing it on the client we had to return a string that gives us this.The number 2 is part of the 2d character array while the rest of the index values are just space characters.
___________
| | | |
|___|___|___|
| | | |
|___|___|___|
| | | |
|___|___|___|
| | | |
|___|___|___|
| 2 | | |
|___|___|___|
I had trouble figuring out how to return this so I started testing it out in another file.
public static void main(String[] args) {
// TODO Auto-generated method stub
char[][] myHidingPlaces;
myHidingPlaces = new char[5][3];
myHidingPlaces[0][0] = 'p';
char play = '1';
for (int i = myHidingPlaces.length-1; i >= 0 ; i--) {
[code]...
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Jun 1, 2014
Basically, it's to write a method that takes in, and then returns another array, whose first element is the average of the first two numbers, last element is the average of the last two, and then everything else is just the average of that index, the one before, and the one after. {1, 2, 4, 8} would return {1.5, 2.33333, 4.66666, 6}.I'm currently getting everything fine, except am not getting the last number (i.e. '6').
public class Arrays {
public static void main(String [] args){
double [] a1 = {1, 2, 4, 8};
for (int i = 0; i < a1.length; i++)
System.out.println(a1[i]);
[code]....
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Jun 13, 2014
The id variable is the problem Java Code: package com.cjburkey.games.boxee.objects;
import java.awt.Graphics;
import java.awt.Rectangle;
import com.cjburkey.games.boxee.GameState;
import com.cjburkey.games.boxee.resources.Images;
public class Block extends Rectangle {
[code]...
In the constructor, it returns corrent numbers, in the draw method, it returns 0. Why?
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Jun 9, 2014
Before I created the data file are the points of x and y I created a model class that represents the graph. I have a problem with making a function that returns the panel of the graph.
Attached File(s)
data.cvs.txt (726bytes)
Number of downloads: 12
chart.txt (3.72K)
Number of downloads: 10
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