FileReader - Returning Null
Jan 12, 2014
I'm following a tutorial and I can't work out why the version that I have written is returning null when reading the text file...?
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class AppReadFileFileReader {
public static void main(String[] args) {
File file = new File("test.txt");
BufferedReader br = null;
[Code] ...
I can't see any difference in the code though, and the files being found in order for the null to appear... :?
the text file is within the Java project, and just has three lines :
line one
line two
line three
That's all it say..... But all my program returns is the work 'null'
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Sep 25, 2014
I am working on a project which manages an airport's airplanes and flights based on user input. The method printFlights() - lines 133-134 - is returning null and I can't figure out why. The method is supposed to print information about each flight. The logic is identical to the printPlanes() method which is working successfully.
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Jun 16, 2014
When I try to getNextMailItem,it keeps returning null.Why?
public class MailServer
{
// Storage for the arbitrary number of mail items to be stored
// on the server.
private HashMap<String,ArrayList<MailItem>> mailbox;
/**
* Construct a mail server.
*/
public MailServer()
[Code] .....
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May 18, 2015
I am trying to return an array and I keep getting a null error. The below class sets the material numbers into an array and should return that array if called :
public class Jobs {
private int[] materialsNumber;
//change to parts and create another class that gets the materials for the parts
public int[] job1() {
materialsNumber[0] = 11960120;
[Code] ....
I later try to call the method. The program executes but stops after I println "test in loop"
public class PurchaseOrdersToParts {
private Jobs job = new Jobs();
int[] getPartsForPurchaseOrder(BigDecimal purchaseOrder) {
System.out.println("inside getparts");
BigDecimal testNum = new BigDecimal(123.0);
[Code] ....
This is the method that is calling the method in the GenerateOrdersToParts class
private PurchaseOrdersToParts purchaseOrdersToParts = new PurchaseOrdersToParts();
@Inject
PoRepository poRepository;
public GenerateShopJobTickets() {
[Code] .....
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May 22, 2014
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.lang.Comparable;
import java.util.*;
import java.lang.*;
public class MyLinkedListSort {
[Code] .....
Output is :
name is nulland salary is0
name is nulland salary is0
name is nulland salary is0
name is nulland salary is0
Expected output :
Name is Crish Salary: 2000
Name is Tom Salary: 2400
Name is Ram Salary: 3000
Name is John Salary: 6000
Where i going wrong
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Nov 7, 2014
I've been assigned to create a Black Jack game with a gui. In this game I've created a seperate Player and Dealer class, and both initiated them, however when I try to call a Player object in a certain way I get a null pointer reference. (It should be noted that the Player object is an array)
public void runGame(){
while(running){
while(dealer.getPoints() <=19){
int count=0;
[Code] .....
And this is how I've initilized the Player class in the constructor
Player[] players = new Player[numberofplayers];
for(int i=0; i<numberofplayers; i++){
players[i] = new Player(i);
players[i].setDeck(d1);
gui.add(players[i].getPanel());
}
What I don't get is if I change players[i] to dealer, it works fine.
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May 24, 2015
The question pretty much says it all, but I tasked myself with creating a program about lemurs. There are multiple class files in this program. In the below code snippet, I have my TreeLemur.class which extends to the Lemur.class which extends to the Mammal.class. However, when I create a Tree Lemur object in the main program, it is returning null consistently from certain methods. What am I doing wrong here?
TreeLemur.class :
public class TreeLemur extends Lemur {
private String groupSize;
private String diet;
private String fur;
public void setGroupSize() {
groupSize = "
Group Size: Large";
}
[Code]...
As of yet, I'm just trying to get Tree Lemur working properly to continue with creating the other if-branches within the main program.
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Jul 12, 2014
I want to read in a text file(list of Names) using FileReader than Write to another file using FileWriter. Using FileWriter, I only want to write the Name starting with F to a new text file. I have the file reading from one text than writing to another text. The tricky part is filtering the names starting with only F.
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Oct 19, 2014
I'm doing homework and as far as input, my assignment reads: "Your program must take as input the name of a Java source code file such as the source file containing the source code of this assignment." So my question is, how do i do that without linking the directory directly (i.e. C:/users/...)? I'm using FileReader as shown below...
public static void main(String[] args) throws Exception {
FileReader file = new FileReader (WHAT GOES HERE???);
BufferedReader reader = new BufferedReader(file);
String s = "";
String line = reader.readLine();
[Code] .....
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Apr 16, 2014
I'm getting an error on line 137 and all it is rsmd = rs.getMetaData();The error happens only after I press a JButton and it is
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerExceptionat softwareDesign.createAccount.actionPerformed(createAccount.java:137)
There is a lot more to it but that has nothing to do with my code it's just the stuff with Eclipse anyway I want to know how do I fix this problem?
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Feb 28, 2015
public class Test {
public static void main(String[] args) {
Car c = new Car();
c.setInf("toyota", "red");
System.out.println("name: "+ c.brand + " colour: " + c.colour);
[code]....
Why do I get the result brand null, colour null? I know what null means but what am I missing here?
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Mar 19, 2014
I have a few questions relating to I/o files.
1.) Is FileReader class the same as File Class. In my book it uses File class to read data from a file, but one of the members here used FileReader so I was wanting to know if it's identical function or not.
2.) When creating an output file, I will use
PrintWriter outputfile("hello.txt")
i just read a new topic of " appending data to a file," meaning if I want to preserve the old file I would have to use this. From my understanding all this does is prevents the old data from being deleted.
Now, in my code if I type ( "hello.txt",true)this would preserve the old data?
One more thing, what does this even do
[CODE]FileWriter file=new FileWriter; PRINTWRITER output=new PrintWriter(file) [CODE/]
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Apr 29, 2014
I'm new to Java and I have a problem with a method, I can't see the code of the method, I just have a jar, but it should return a boolean, something like this:
boolean band = false;
band = TestClass.testMethod("blabla");
// band = false
The problem is that the method seems that is returning nothing (band remain false), and if I initialize band to true:
boolean band = false;
band = TestClass.testMethod("blabla");
// band = true
band remain true, in other words, the value of band is never modified, the question is, how is this possible? because it should return the same value on both calls, true or false, no matter the initial value of the variable that is receiving the returning value of the method.
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Apr 6, 2015
This simple program should build a new table with random values and on the getValue method (perhaps called from othe TestClass) return back content of particular cell. why my getValue method doesn't work. Nay! It returns error while compilation.
import java.util.Random;
class TablicaIntowa{
public int getValue(int a){
return tabl[a];
} //getValue method end
[Code]....
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Nov 22, 2014
I have created a class and a matrix of doubles (or at least, I think I have, that's partly what I want to verify).I need to return the values of the array,Here is my class:
public class example{
double[][] Position=new double[2][11];
double calculate(){
for (int time=0;time<=10;time=time+1){
Position[1][time]=time;
Position[2][time]=time+1;
double A=Position[2][time];
return A;
}
}
}
I am getting the error: "This method must return a result of type double", though to me it looks like I am returning double (A).
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Jan 4, 2015
I've made a class called Car with a method which will tell me a category for the engine size regarding the actual size (which I've included in the main just so I could see if it works) but everytime I test it I get an error.
public class Car {
public String b;
public String c;
public double es;
public double cs;
public String getCategory() {
if (es < 1.3)
[Code] ....
Figured it out. Was missing parenthesis on audiCar.getCategory();
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May 14, 2014
i am trying to run a command in terminal the code is below if i run the command in terminal it works fine however when i run it from netbeans with code below nothing gets printed. however if i run a different command such as (ip addr) it works fine?
public static void a() throws IOException{
ArrayList lister=new ArrayList();
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("ps -ef | grep firefox");// the command i am trying to run to get pid of application
InputStream stderr = proc.getInputStream();
[Code] ....
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Oct 12, 2014
I am writing a code where in the first method the question will ask whats your favorite website. for example www.javaprogrammingforums.com...when it outputs it will read just "javaprogrammingforums" without the www. and the .com.
Because the program will ask a series of questions in the main, I would like website question to be returned to the main. Here is my code, and what can I do?
import java.util.Scanner;
public class chapter3 {
public static String website(Scanner kb) {
String website;
System.out.println("What is your favorite website?");
website = kb.next();
[Code] ......
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Sep 1, 2014
I'm having an issue returning data from a constructor. This is an assignment, and the specifications were that two classes are to be used, one for the variables and assigning methods, and one for the main method and the printing. This app compiles, but returns "0" for the isbn number, and I'm sure it's because I'm not doing something right with my constructors. My code is below
public class Book {
/* Declare Variables */
public static int isbn;
/* Constructor */
public Book (int isbn) {
isbn = 454545;
[code]....
There are other variables to add, but if I can get one working, I can get the rest working.
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Sep 24, 2014
The code is below. The program runs a series of calculations based on data input by the user. My problem is that for the most important thing I'm looking for, total kg CO2 emissions, I continually get an answer of 0.0. What I need is a sum of the individual total emissions as calculated in each method, i.e. the values which are printed with the following: System.out.println(trans); System.out.println(elec); and System.out.println(food);
The total should be something like 25040 or whatever, depending on the value of the inputs provided by the user, but I'm constantly getting a total of 0.0., which is obviously false. Could have something to do with the way I've initialized my variables, or something to do with the limitations of returning values from methods.
import java.util.Scanner;
public class CarbonCalc {
public static void main(String[] args) {
double trans = 0;
double elec = 0;
double food = 0;
giveIntro();
determineTransportationEmission(null);
[code]....
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Mar 27, 2014
I want to return multiple values in my EJB query. The query goes something like this:
SELECT SUM(s.sales) SUM(s.cancels) FROM accounts.
To implement this if I write as below:
Query query = _em.createNamedQuery("Accounts.findAccountData");
Now if I do query.getSingleResult(); how do i retrieve both the values since the ejb finder returns either a single object or a collection?.
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Jul 15, 2014
For some reason my code returns the memory address of the array when its a print statement with a string, but it works fine when its in a separate print statement all by itself. Why? Do I need to create a toString method that converts a char array to a String to something? The reason why I ask that is becuase on Eclipse line 10 has a warning stating "Must explicitly convert char[] to a String".
public class Ex {
private String word;
public Ex(String word) {
this.word = word;
}
public char[] Display(){
char[] wordChars = this.word.toCharArray();
return wordChars;
[Code] .....
Result:
Hello world
The word is: [C@1db9742
I also tried this, knowing that it's a long shot, but that didnt do anything...
public String toString(){
Ex ex = new Ex(this.word);
char[] word = ex.Display();
String updated = word.toString();//counter intuitive?
return updated;
}
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Jan 7, 2014
I have a for each loop that outputs the Mechanics salary for the first team in the arraylist, how can I add these figures together instead of having separate value for each?The code in my testing class to get the salary for mechanics:
Java Code: for (Mechanic str1: formula1.get(0)){
System.out.println(str1.getSalary());
} mh_sh_highlight_all('java');
How can I also get the salary for the driver 1 + 2 in the same team and add their salary to this? I have attaached an image showing the classes/fields created
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Apr 10, 2014
public int[] allIndicesOf(E itemSought) {
ArrayList<Integer> toUse = new ArrayList<>();
for (E anArray : container) {
if (anArray.equals(itemSought)) {
toUse.add(container.indexOf(itemSought));
[Code] ....
I have an array list of strings. I want to be able to return an array of integers telling me which indexes in the string array list contain the itemSought object.
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May 13, 2014
Write a method that accepts an array of Strings and a character c. The method must return the count of all cs in the strings of the array.
Here's what I have written:
[
public int countC(String[] strings, char c) {
int count = 0;
for(int i = 0; i < strings.length; i++) {
for(int j = 0; j < strings[i].length(); j++) {
if(strings[i].charAt(j) == c) {
count++;
}
}
}
return count;
}]
Does this look correct?
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Jan 23, 2015
I'm writing a program that involves the use of set/get methods. I will submit a sample code of my issue. The format appears to be alright however the program is not returning any data. This is the same format as my actual code. Why this might be happening?
Java Code:
public static void main(String [] args) {
SecondClass object = new SecondClass();
object.setName("Name");
object.getName();
} mh_sh_highlight_all('java');
Java Code:
public class SecondClass {
private String name;
public SecondClass(){
name = " ";
}
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
} mh_sh_highlight_all('java');
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