As part of a homework assignment in my 1st Java Class, I am creating my own Circular Generic LinkedList and Array class. My class uses the Queue Interface Extends Iterable but I am creating my own methods to work with. For the most part, I believe I have been successful in creating the class aside from one method. That method is the Iterator<E> iterator().
/**
* Return a fail-fast iterator, which throw a java.util.ConcurrentModificationException
* if the client modifies the collection (via enqueue(...) or dequeue()) during iteration.
*/
@Override
public Iterator<E> iterator() {
I don't understand how an iterator, let alone a "fail-fast" iterator ties into my project. I've spent hours reading up on a way to imploy my own generic fail-fast iterator but to no avail.
I feel like I could come up with some workable code if I knew what the point is to useing a user-defined, non Java Library iterator is to do.
As well, does throwing a ConcurrentModificationException require a try and catch block?
I have a problem that is associated with Fast Fourier Transform of an image. I've made an application with some filters for an images. It's a program with JLabels for displaying images before and after filtration and JButtons for filters. So, my problem is with FFT for an image, i've seen examples for that transformation, but i really don't know how to use that in my program.
I'm trying to implement fast fourier transformation using recursion, at line 28 I'm getting null pointer exception.The algorithm is suppose to break the array in two parts computes real' and imaginary' at the end to each call stores the value in each call. After which further divide the array in two parts and compute.
I'm currently working on a RSA Encryption using Fast Exponential technique. As the numbers I'm working with will be very huge, I am forced to use BigInteger.
As this is the first time I'm using Big Integer, I encountered quite a number of issues. I'll try my best to explain the errors I'm facing:
1. I had done this step: BigInteger d;
So I'm currently trying to get d = 0;
However, I keep getting an error required: BigInteger, found int.
When I changed it to d = new BigInteger(0) , I get this error:
java:19: error: constructor BigInteger in class BigInteger cannot be applied to given types;
d = new BigInteger(0); ^ required: no arguments found: int reason: actual and formal argument lists differ in length
Part of Code:
public class BigFastExponential { BigInteger e; // public exponenet: all has this BigInteger d; // private key: only key owner has this BigInteger n; // public modulus: all has this
/** * Create a LongRSA object for a public key holder, with just e and n. */ public BigFastExponential(BigInteger public_e, BigInteger public_n)
I have inherited some code that is supposed to work just fine. The trouble is that when everything is rebuilt on my desktop, the projects crash. They all seem to crash at one particular part of code.
I pass it a string and the "getResource" or "getContentClassLoader" is failing.
[URL] ....
I guess one way to tackle this is to break it apart into segments.
I have inherited some code that is supposed to work just fine. The trouble is that when everything is rebuilt on my desktop, the projects crash. They all seem to crash at one particular part of code. I pass it a string and the "getResource" or "getContentClassLoader" is failing.
I'm writing a simple program in which I have a super class Person, inherited by the subclasses Customer and Employee (they inherit the variables ID, name and surname).
Java Code:
public class Person { int id; String name; String surname; public Person () {
[Code] .....
However the problem is here: when I try to get the variables ID, name and surname through my main class, they fail to return (0,null,null). Why is this? I have get-Methods in my subclasses which should return the super variables, but they are not.
Java Code:
public String getUser() { return username; }
public String getName() { return super.name; } mh_sh_highlight_all('java');
I have a task of returning US holiday based on the given date and this utility will be used in a multi thread environment. I have written as below, how to know if my code breaks at any given point by multiple threads
I tried to test this with few concurrent threads, and noticed that the DB call is made for the very first time or when the year being requested is not same as the cached year. But I wanted to see, if this is properly synchronizing and would not fail in any case. My intention is to make a singleton HolidayCalendar, and also synchronized well enough so that every thread using this class gets the required data without blocking each other.
I need to find out if one array list is a sub-sequence of another. The elements in the first list all need to be in the second list and must be in the same order. So s1<n, t, a> is a sub-sequence of s2<q, n, f, r, t, d, a>, but s1<a, a, t> is not a sub-sequence of s2<a, t, a>. I need to use iterators to go through each list, and I should only go through each list once (since it has to be in the same order) so nested loops don't seem like they would work because it would start at the beginning of one list every time it moved to another element in the outer loop's list.I seem to have an issue where the itr1. next() is ignored when in an if statement.
My current code just stalls and will never stop running. I've also switched things around and put the not equal check after the if it is equal and it throws a NoSuchElementException.
import dataStructures.*; public class Subsequence3 { public static void main(String[] args) { ArrayList<Character> s1 = new ArrayList<Character>(); s1.add('n'); s1.add('p'); s1.add('a');
I am trying to add the contents of the iterator to an arraylist so I can do other stuff to it, however I am getting an error when I actually try adding it to the list, stating that
"The method add(Map.Entry<String,myObject>) in the type ArrayList<Map.Entry<String,myObject>> is not applicable for the arguments (myObject)"
Here is what I have tried doing:
Iterator<Map.Entry<String, myObject>> iterator = hash.entrySet().iterator();//hash is my HashMap object ArrayList<Map.Entry<String, myObject>> list = new ArrayList<Map.Entry<String, myObject>>(); while(iterator.hasNext()){ Map.Entry<String, myObject> entry = iterator.next(); list.add(entry.getValue());//error here }
I am trying to use an iterator instead of a foreach loop to go through a list of inventories to see if a car is rearDrive and count how many are rearDrive but somehow I seem to be missing something that the counter isn't working as expected.
public int howManyAreRearWheelDrive(){ int i = 0; int counter = 0; int inventSize = inventory.size()-1; while(i < inventSize){ boolean wheelDrive = inventory.get(i).getIsRearWheelDrive(); if( wheelDrive == true){ counter++; } } return counter; // returning here doesn't give me anything }
The Iteratior provides the functionality of traversing and removal which we can achieve through normal for loop and remove() of the data structure.Then, why do we need Iterator explicitly and as an inner class?
Each numeric value in the file is an indication of the number of occurrences of each feature (e.g., forest, tree) multiplied by a given penalty. To generate instances from such a file, I use the following Java code:
I then add the so-generated instances to my model using the instruction model.addInstances(generatedInstances). The resulting output is described below.
It contains errors caused by the instruction model.addInstances(generatedInstances). Debugging my code showed me that the alphabet associated to the model is null. Am I using the wrong iterator?
// 2009 nobelPrizeWinners.put("2009 Physics", new PrizeWinner[] {new PrizeWinner("Charles K.", "Kao"), new PrizeWinner("Willard S.", "Boyle"), new PrizeWinner("George S.", "Smith")}); nobelPrizeWinners.put("2009 Chemistry", new PrizeWinner[] {new PrizeWinner("Venkatraman", "Ramakrishnan"),
[Code] .....
At the moment, my output is:
2008: Chemistry: Osamu Shimomura, Martin Chalfie, Roger Y. Tsien 2008: Economics: Paul Krugman 2008: Literature: Jean-Marie Gustave Le Clézio 2008: Medicine: Harald zur Hausen, Françoise Barré-Sinoussi, Luc Montagnier 2008: Peace: Martti Ahtisaari
[Code] .....
However, I need a blank line between the final entry of 2008 and the first entry of 2009.
My homework is a Double Circular Link list and when i write implements Iterator it gives me a an error when I compile it the same for my subset method...
ERRORS :DoublyCircularList.java:55: error: DoublyCircularList.iterator is not abstract and does not override abstract method remove() in Iterator public class iterator implements Iterator<T> ^ Note: DoublyCircularList.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 1 error
import java.util.Iterator; public class DoublyCircularList<T extends Comparable<T>> extends LinkedList<T>implements Iterable<T> { Node<T> first; int size; public DoublyCircularList(){ first = null; size = 0;
List<Integer> list = new ArrayList<Integer>(); for (int i = 0; i < 5; i++) { list.add(i * 3); } ListIterator<Integer> listItr = list.listIterator(); System.out.println("Traversing in a forward direction");
[Code] ....
Output:--
Traversing in a forward direction 0 3 6 9 12 Traversing in a backward direction 12 9 6 3 0 425
Why 425 is not showing when we are traversing in a forward direction.
I'm not new to java but i'm not able to solve the following issue: I have a class
public class Localizzazioni implements java.io.Serializable { private <complexType> id; public getId()....... public setId().....
The complexType is a class defined in the code somewhere. Now I want to access it in another class I have
Set localizzazioni = new HashSet(0); localizzazioni=opere.getOiLocalizzazioneOperas(); -- this object give an object of tyoe HashSet for(Object object : localizzazioni) { object.get......... // i cannot use any method defined in the class Localizzazioni }
Why I cannot write inside the for object.getId() and using it?? In other word how i can access the element contained in the object?? the object is an iterator of type Localizzazioni . The class Localizzazioni has some method but i cannot use them? why ....
I have been researching the Iterator and making a class implement iterable. I have seen this example shown below and was wondering how I could change this so that iterable() is not called upon in the main. I would like to be able to make a method that returns an instance of a class that implements the Iterator interface hopefully an inner class. This is because my program will not have a main and will be supplied with a main that includes a new Object with will use the iterator method.
import java.util.*; public class IteratorDemo { public static void main(String args[]) { // Create an array list ArrayList al = new ArrayList(); // add elements to the array list al.add("C");
[Code] ....
This is all I have been able to understand from what I want to do. This does not work and this is what I am trying to achieve
public class MyArrayList implements Iterable { public static final int DEFAULT_SIZE = 5; public static final int EXPANSION = 5; private int capacity; private int size; private Object[] items;
I am working on a project that uses a custom tag in a JSP file. Here is the tag descriptor
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"> <taglib> <tlibversion>1.0.0</tlibversion> <jspversion>1.1</jspversion>
[code]...
Everything seems working fine except that the custom tag handler does not get called at call. I set breakpoint and it never stops there. The JSP page is displayed fine, only not showing the custom tag content and there is no logged error/warning from the log. The tld is found fine. Like what classes called/validated the tag handler so I can logging those classes at DEBUG level to see what goes wrong.
I would like to create a custom tag which works similar to <c:forEach/> tag i.e
<c:forEach var = "movie" items = "${collection}> ${movie} </c:forEach>
I would want to create the similar behaviour(as above) in my own custom Tag.Morever I would like to use the doStartTag() and doEndTag() and doAfterBody() methods while creating custom Tag.
My jsp page needs to have a dropdown box. on selecting one/more than one values from this list, the same values get populated in another one.. we have a delete button too , it allows to populate the second box again.
The thing is i am to avoid scripts and use custom tags as much as i can...
