Type Name And Get Histogram - Getting NullPointerException
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!
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;
I prompted the user to enter inches of rainfall for seven days and stored them in an array. Now, I am trying to display a histogram of this data using a nested loop, but for each inch, I have to display a * like this:
The only way I know how to display a number of *s according to user input is by an if statement. I copied and pasted from a similar class assignment I did, so what I have so far is pretty messy and nonsensical:
The following program should read in a file on my desktop (I have the path set in Netbeans to that location) and produce a Histogram. Instead I am receiving this error.
Exception in thread "main" javax.imageio.IIOException: Can't read input file! at javax.imageio.ImageIO.read(ImageIO.java:1301) at Histogram.main(Histogram.java:9) Java Result: 1 BUILD SUCCESSFUL (total time: 0 seconds)
Here is the code for the Histogram:
import java.awt.image.BufferedImage; import java.io.File; import javax.imageio.ImageIO; public class Histogram { public static void main(String[] args) throws Exception { int[][][] ch = new int[4][4][4];
Design and implement an application that creates a histogram that allows you to visually inspect the frequency distribution of a set of values . The program should read in an arbitrary number of integers that are in the range 1 to 100 inclusive; then produce a chart similar to the one below that indicates how many input values fell in the range 1 to 10, 11 to 20, and so on. Print one asterisk for each value entered.
No input prompt
Terminate input by typing CTRL/Z (two keys typed at the same time) on a separate input line (use CTRL/D on Linux/UNIX systems)
Use hasNextInt() to terminate your input
Format as below (slightly different from the text example)
Z:dbraffittWeek10> javac Histogram.java
Z:dbraffittWeek10> java Histogram
10 10 10 10 10 20 20 20 20 20 20
20 25 35 45 55 65 75 85 95
ctrl/z
1 - 10 | *****
11 - 20 | *******
21 - 30 | *
31 - 40 | *
41 - 50 | *
51 - 60 | *
61 - 70 | *
71 - 80 | *
81 - 90 | *
91 - 100 | *
What I can not figure out is how to use hasNextInt() to terminate the loop. How to not have an input prompt. How to use ctrl z to terminate the input. Or to make it where it doesn't involve range values like -1.
Java Code:
import java.util.Scanner; public class Histogram { public static void main (String[] args) { Scanner scan = new Scanner (System.in); int [] nums = new int[101];
Design and implement an application that creates a histogram that allows you to visually inspect the frequency distribution of a set of values . The program should read in an arbitrary number of integers that are in the range 1 to 100 inclusive; then produce a chart similar to the one below that indicates how many input values fell in the range 1 to 10, 11 to 20, and so on. Print one asterisk for each value entered.
No input prompt Terminate input by typing CTRL/Z (two keys typed at the same time) on a separate input line (use CTRL/D on Linux/UNIX systems) Use hasNextInt() to terminate your input Format as below (slightly different from the text example) Z:dbraffittWeek10> javac Histogram.java Z:dbraffittWeek10> java Histogram
[Code] ....
What I can not figure out is how to use hasNextInt() to terminate the loop. How to not have an input prompt. How to use ctrl z to terminate the input. Or to make it where it doesn't involve range values like -1.
import java.util.Scanner; public class Histogram { public static void main (String[] args) { Scanner scan = new Scanner (System.in); int [] nums = new int[101];
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.
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.
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');
/** * 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?
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)
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
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,
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)
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();
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();
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.
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.
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(...).
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:
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:
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;
If you have final int i = 1; short s = 1; switch(s) { case i: System.out.println(i); }
it runs fine. Note that the switch expression is of type short (2 bytes) and the case constant is of type int (4 bytes).My question is: Is the type irrelevant as long as the value is within the boundaries of the type of the switch expression?I have the feeling that this is true since:
byte b = 127; final int i = 127; switch(b) { case i: System.out.println(i); }
This runs fine again, but if I change the literal assigned to i to 128, which is out of range for type byte, then the compiler complains.Is it true that in the first example the short variable and in the second example the byte variable (the switch expressions) are first implicitly converted to an int and then compared with the case constants?
Got a problem with generics, which I'm still pretty new at. Here's a program that compiles fine:
import java.util.ArrayList; import javax.swing.JComponent; public class Experiments { public static void main(String[] args) { ListHolder holder = new ListHolder();
[Code] ....
It's useless, but it compiles. If I change Line 14, however, to add a generic type parameter to the ListHolder class, Line 10 no longer compiles:
import java.util.ArrayList; import javax.swing.JComponent; public class Experiments { public static void main(String[] args) { ListHolder holder = new ListHolder();
[Code] ....
I get this error:
Uncompilable source code - incompatible types: java.lang.Object cannot be converted to javax.swing.JComponent at experiments.Experiments.main(Experiments.java:10)
Apparently, the introduction of the type parameter leaves the compiler thinking that aList is of type Object. I can cast it, like this:
JComponent c = ((ArrayList<JComponent>)holder.aList).iterator().next();
That makes the compiler happy, but why is it necessary? How does adding the (unused) type parameter to the ListHolder class end up making the compiler think the aList member of an instance of ListHolder is of type Object?
I'm trying to parse and compare the content of a zip file. However I'm stuck at what SHOULD be a very simple problem, however I can't seem to find a solution. I have done the following:
ZipInputStream zin1 = new ZipInputStream(fin); ZipEntry ze1 = null; fin2 = new FileInputStream(fileName2); ZipInputStream zin2 = new ZipInputStream(fin2); ZipEntry ze2 = null; //fin.close(); ze1 = zin1.getNextEntry(); ze2 = zin2.getNextEntry();
Which gives me the first entry of each zipfile as a ZipEntry type object. I have tried getting the path of the file (inside the zip file) and using this to create a File type object. This does not seem to work though I get:
Exception in thread "main" java.io.FileNotFoundException: My DocumentsmetadatacoreProperties.xml (The system cannot find the file specified) at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.<init>(Unknown Source) at java.io.FileReader.<init>(Unknown Source)
And this is because I get a null return from trying to create the File file1 = new File(correctLocation);
I guess I cannot access the file inside a zip file this way. So my question is how can I make a ZipEntry type object into a File type object?
