How To Avoid NullPointerException

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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Why Is There A NullPointerException

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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Getting A NullPointerException Error?

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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How To Avoid Empty Map Value In A List

Apr 24, 2014

I have a HashMap with multiple values at runtime. In that map one key has empty value , how to avoid this value to add in a list. some code sample is below:

public HashMap getLoop2Map(Map map, String xslFile , int sheetNo){
HashMap hashMap = new HashMap();
try{
ArrayList list = new ArrayList();
System.out.println("-------Map : " +map);
list.add(map.values());
//System.out.println("------- boolean : " +val);
System.out.println("------List : " +list);
}

I do not want to add the empty value in a list ...

result in map

-------Map : {Free Text Entry={},
Mouth / Throat={Free Text Entry={Free Text Entry=<FORMFILENAME>EditChartPhysicalExamText.form
</FORMFILENAME><TAG>"<MUSCULOSKELETAL.PE>"</TAG>},
Salivary Glands Condition={Salivary Glands Condition=MouthAttribute},
Examination Overview- Mouth / Throat={Examination Overview- Mouth / Throat=MouthAttribute},
Tonsils={Tonsils=MouthAttribute},

[Code] ....

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Avoid Duplicates On ArrayList

Nov 5, 2014

I'm struggling with that piece of code, my intention is to check for the object I want to add before adding it, so there won't be any duplicate on my list. I'm not sure how could I do that, since I'm working with objects.

Person is a class with few parameters such as id, name, and few others.

I guess I should search for a person with the same id, since that has be unique, but can't get it right.

private ArrayList<person> model= new ArrayList<>();
//...
if (model.contains(person))throw new IllegalArgumentException("duplicate");
else model.addElement(person);

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Jul 25, 2014

is it possible to avoid deadlock while coding..

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Feb 12, 2014

How to avoid hard coded href url .

For example a href="www.yahoo.com">

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NullPointerException Under IF Statement Which Should Be Skipped

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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Programme Producing NullPointerException

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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NullPointerException With Hashtable Object

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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EJB / EE :: Java JAX-WS Client NullPointerException

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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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!

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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How To Avoid Keyboard Auto-repeat

Oct 8, 2014

I wanted to make a small program to move a small rectangle by pressing the WASD keys. The program works, except that when I hold a key to move the rectangle, after a second, auto-repeat starts up, and the rectangle motion accelerates. I want to prevent automatic repeat to activate, so that the rectangle moves at a constant speed when I hold a key and stops when I released. Here is the ButtonMotion classe :

import java.awt.event.ActionEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.KeyStroke;

[code]....

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Oct 18, 2014

how to avoid getting negative numbers of coins, use casting and mod to show how many quarters, dimes, nickels, and pennies there are?

import java.util.Scanner;

public class VM
{
public static void main(String[] args)
{
//money deposit
Scanner input = new Scanner(System.in);

[code]....

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Jun 17, 2014

I have code which query value from database,the use case is the user can enter value as 1,01,11 in database but when the user enter value in xml file he can only enter 11,01,12 in database there is two columns lets say column test1=1 and test2=2 combination of this is 12,which is the value the use will enter in xml, but sometime the use can enter test1=04 than column test2=00 ....

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Dec 9, 2014

I'm using EclipseLink, WildFly, EJB, postgresSQL and JSF.I'm trying to persist some countries and their localities.So I've:

- Two entities Countries and Localities in which I specify respective columns and relations.
- Abstract Session beans for entity classes: AbstractFacade providing basic crud methods and entity manager.
- Two concrete session bean for entity classes: CountriesFacade and LocalitiesFacade.
- A JSF managed bean named geoJSF.
- A JSF page with a form allowing to insert new country and localities.

In geoJSF I'm injecting via EJB CountriesFacade as property named cf and LocalitiesFacade as property named lf.For the actual inserting country and locality I'm using geoJSF.country and geoJSF.locality. When the form is submitted I'm simply doing:

this.cf.create(this.country);
this.locality.setCountry(this.country); //<- this throw an exception (unique constraint violation) due to the attempt to reinsert this.country
this.lf.create(this.locality);

I disabled all cascade among relations definitions.Based on what I know this.country should appear detached to entity manager so, setting relation the entity manager try to re-persist it.

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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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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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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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Jan 12, 2014

Write a program to copy file from c: drive to another drive and avoid duplication??????????

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Jul 28, 2014

I am trying to call another swing frame from my current frame. And after calling second frame i dispose the current frame.

But while second frame coming on the screen, current frame gets dispose and second frame takes some seconds to appear on screen.

So its creating a bad flickering effect on screen and its not suitable for my application.

I want that first frame will call sencond frame and it will not look like second frame is called. I just want to cancel flickering effect.

Here is my source code.

1st Frame:

public class Welcome extends JFrame {
JFrame f;
JTextArea nameField,nameField1;
JLabel lable;

[Code] .....

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Feb 16, 2015

The method I am trying to successfully write is startsWith(String s1, String s2)

The intention of the code is to return true if s2 starts with the string s1, and false otherwise. For example,

x.startsWith("Maplestory","Maple"); Should return true.

This code partially works, depending on the values entered into it. When it is supposed to return true, it does do this. When it is meant to return false, I get a StringIndex OutOfBounds Exception.
 
public class CC02{
String remove1(char c, String s){
String to_return="";
while(true){
if(s.equals(""))
return to_return;

[Code] ....

The method I have written uses one other method from my code, which is "reverse". Any way to return false without getting this error.

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Apr 7, 2014

I'm writing an IRC server in Java, however when a client tries to connect I get a ConcurrentModificationException trying to add them to an ArrayList. My code is Here: [URL]

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Mar 28, 2014

I have a practice program (written with NetBeans IDE 7.4) that calls methods to:

(1) fill an array with user input values

(2) sort the array values into ascending order

(3) print the array in assorted order.

(4) print the array without any duplicates

Method (4) prints the contents of the array without printing any duplicates. That is, if a number in the array has already been printed, it will not be printed again.

Method (4) seems to work, but may be inefficient or I may have done too much work making it difficult on myself or making the logic too confusing.

Is there a better way to do this WITHOUT using built-in functions in Java's library?

(Such as writing this method using for loops and counter variables: As practice I am supposed to avoid using Deleting functions for duplicates)

Here is my code:

public static void Duplicates(int [] array){
int duplicates = 1;
String Output = "";
for(int i = 0; i < array.length -1; i++) {
if (array[i] != array[i+1]){
duplicates ++;

[Code] .....

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