Implement A Priority Queue
Apr 15, 2014Implement a priority queue based on a sorted linked list. The remove operation on the priority queue should remove the item with the smallest key.
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Print Queue Using Priority Q Simulation?
Nov 28, 2014I have a class "ExecuteJob" which has Print Q in the form of Priority Q.
You can keep adding job to the Q by calling one of the method in the class. However, and object cant do things simultaneity can it? While im adding a new job to the print queue, can it be executing and existing job in the print Q.
To achieve that, I would need to implement process and threads? I believe am I right? So that adding a job is independent to being removed?
Priority Queue Implementation Using Heap / BST
Dec 4, 2014I am in the process of implementing Priority queue, as I understand that there are many data structures you could use to implement. I implemented it with the an array, which it works absolutely fine. However I have limitations on what collections I can use from the collections classes. I fact I cant use any of the collections classes. Meaning I cant use array.
I’m trying to implement Priority Queue using heap. And implementing heap using binary trees. But however I have a few questions which I need to clarify and I cant think of any other way of resolving it. Ofcourse I can implement my own simple array class using linked list.
Inserting into heap would be quite simple, as I just need to find the right last position from left to right leaf to insert the node into the tree. However after inserting, you may want to make sure that leaf node values are > than root node. Therefore, the root node will always be with the highest priority.
I call these steps where you compare from top down as bubbledown and bubbleup. To do this I really need a for each node within the treee node to have attribute pointing to its root node. So in case of bubbleup I always have a pointer for a given node to its root, without it would mean I would to traverse through the entire tree to identify its root. Which I believe is very inefficient.
Or have I taken this completely wrong? Or is it the case that heap are only best with arrays and therefore use array (by implement it using linked list?)
Sorting Priority Queue Containing Objects
Mar 30, 2014I have a PriorityQueue called incoming, containing objects of type Vehicle.
All vehicles have a fuel level, that can be accessed by the getter method getFuelLevel().
I want to be able to choose to sort the queue so that the Vehicles with the lowest fuel levels are at the front of the queue.
Priority Queue In Java Which Keeps Track Of Each Node Position
May 4, 2014I'm working on a lab for my class. I need to create a Priority Queue in Java using an array list. The kicker is that each node has to have a "handle" which is just an object which contains the index of of the node that it's associated with. I know that sounds weird but we have to implement it this way. Anyway, my priority queue seem to work fine except the handle values apparently aren't updating correctly because I fail the handle test. Also, I run into problems with handles only after extractMin() is called, so I figured the problem would be somewhere in that method but I've been through it a million times and it looks good to me.
Here is my Priority Queue Class:
package lab3;
import java.util.ArrayList;
/**
* A priority queue class supporting operations needed for
* Dijkstra's algorithm.
*/
class PriorityQueue<T> {
final static int INF = 1000000000;
ArrayList<PQNode<T>> queue;
[Code] ....
I can post the tests too but I don't know if that would do much good. Just know that the queue works as is should, but the handles don't point to the right nodes after extractMin() is utilized.
Comparable Class - Create Priority Queue For Airline Passengers
Oct 9, 2014My assignment was to create a priority queue for Airline Passengers. Here is what I have done so far:
//Driver
package priorityqueuestandby;
import java.util.NoSuchElementException;
import javax.swing.JOptionPane;
public class PriorityQueueStandBy {
public static void main(String[] args) {
[Code] .....
So the part that I cant figure out is:
When a standby passenger is to be enqueued into the priority queue, it must be done so that at the moment of each dequeue operation, the item at the head of the queue is the standby passenger with the longest longevity, and also so that passengers with the same longevity are dequeued in a first-come-first-served fashion.
he says that we need to "Make your program so that it extends Comparable and implements the compareTo() method properly..."
So I was looking at the Comparable class and I could't find a compareTo() method... I am not confident I know how extends works either. I am assuming I need a new class if I am going to be extending another class. Right now I am taking in longevity as a String and converting it to an int because my last ditch effort is going to be to set up a loop that will organize longevity into a/an circular array based on the size of the incoming integer.
Dijkstra's Algorithm With Priority Queue - Method To Find Minimum Distance Is Nonfunctional
May 14, 2014I was given some code by a professor to add some features to as part of an assignment. However, the code itself doesn't seem to work.
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.PriorityQueue;
import java.util.Scanner;
import java.util.Set;
public class DijkstraPriorityQueue
[Code] ....
The method to find minimum distance is nonfunctional...I receive an error that the types are incompatible. I can't do the assignment if the base code doesn't work to begin with...
Program Used To Implement Palindrome String Of Using Stack And Queue
Jan 8, 2015this program used to implement palindrome String of using stack and queue.i wont to enter string by scanner how can i chang it ??????
class Palindrom_homwork1{
int top=-1;
int rear=-1;
int front=-1;
int max=3;
int max1=3;
char array[]=new char[max];
char array1[]=new char[max1];
[code]....
Stacks And Priority Queues Project
Feb 21, 2014So I have 3 classes in this project, and When it compiles, I get a null pointer.
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class Project2 {
[Code] .....
Regional Zone Information - Set Priority Rating
Feb 1, 2014I have an assignment to complete where I have to develop a Java Console application in Eclipse which accepts regional zone information for premises based upon addresses provided. The program needs to figure out which geographical zone each customer lives in and based upon their age, set a priority rating.
The zones (which is the Belfast and the directions) and sub-zones (which are the Postcode such as "BT1" are:
Zones
BELFAST
"BT1 ", "BT2 ", "BT3 ", "BT4 ", "BT5 ", "BT6 ", "BT7 ", "BT8 ", "BT9 ", "BT10", "BT11", "BT12", "BT13", "BT14", "BT15"
NORTH
"BT39", "BT40", "BT41", "BT42", "BT43", "BT44", "BT45", "BT46", "BT51", "BT52", "BT53", "BT54", "BT55", "BT56", "BT57"
SOUTH
"BT25", "BT26", "BT32", "BT35", "BT60", "BT61", "BT62", "BT63", "BT64", "BT65", "BT66", "BT67", "BT68", "BT69", "BT70", "BT71", "BT80"
EAST
"BT16", "BT17", "BT18", "BT19", "BT20", "BT21", "BT22", "BT23", "BT24", "BT27", "BT28", "BT29", "BT30", "BT31", "BT33", "BT34", "BT36", "BT37", "BT38"
WEST
"BT47", "BT48", "BT49", "BT74", "BT75", "BT76", "BT77", "BT78", "BT79", "BT81", "BT82", "BT92", "BT93", "BT94"
UNALLOCATED
No Postcode provided
What I specifically need to do is
1.Display a count of addresses within a user defined geographical zone.
2.Display all information for customers within a user defined geographical zone.
3.Display a complete set of captured data.
4.Display a prioritized list of customer details within each geographical zone.
5.Display a count of customers within each geographical zone.
Below is the code I have created so far for it.
package assignment1;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class Assignment1 {
private static InputStreamReader input = new InputStreamReader(System.in);
private static BufferedReader reader = new BufferedReader(input);
[Code] .....
The main issue I'm having is to make sure that data like address and customer counts, and customer details appear only for the selected areas.
EJB / EE :: Same Listener MDB For Different Jms Queue?
Feb 21, 2014Is it possible to define the same message driven bean as a listener to different queues?
The goal being to define different redelivery configuration for different kind of messages, but handle them all through a single deployment MDB for unity/entity purposes.
The other option is to have many MDBs targeted to the same source code.
Delete From Queue Not Working
May 29, 2014leaveQ method does not work..To see the other files related to these code click here:(Its a dropbox location) URL....Java Code:
public class CustomerQ {
private int MaxLength;
private int totalCustomers;//assuming #of customers served
int Qlength;
Customer cus;
LinkedList4Q cus4Q;
[code]....
Bank Queue Simulator
Jul 13, 2014I am doing a bank queue simulator program which will figure what will happen in 100 minute where 0 to 2 customers comes every minute. 3 counters will handle these customers each counter will poll the customer after 3 minutes.my problem is queue.poll()is not working in counter method and it is adding null values to the queue in the same method. when i add while customers.isEmpty(); the program will not work i do not know why
package dataalgo;
import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
public class customer {
[code]....
Double Ended Queue
Jan 7, 2015implement Double Ended Queue?????
import java.util.*;
public class DoubleEndedQueueImplHW22 {
ArrayList<Integer> deque = new ArrayList<Integer>();
public void insertFront(int a){
System.out.println("adding at front: "+a);
deque.add(0,a);
System.out.println(deque);
[code]....
Implementation Of Immutable Queue
Nov 12, 2014The following codes shows an implementation of an enqueue function of a FIFO immutable queue, and the output result shows the String "c".
I don't understand why since I expected it should be null.
The head and the tail of an ImmutableQueue Object are two separate queue, and each time I call the enqueue function, it just return a new object with a new tail, however, the head is not modified except the first two times I call the function.
Therefore, I expected head.next.next should be a null element, but the result is not like that.
public class ImmutableQueue<E> {
private int size =0;
public Queue<E> head;
public Queue<E> tail;
public ImmutableQueue(){}
private ImmutableQueue(Queue<E> hd, Queue<E> tl){
head=hd;
tail=tl;
[Code] ....
Finding Palindromes From Stack And Queue?
Apr 30, 2015I'm trying to create a class that takes an String from a Stack and checking if it's a palindrome than taking a another String from a queue and checking if that is also a palindrome.
import java.util.Stack;
public class Palindrome {
public static void main(String[] args) {
// TODO Auto-generated method stub
String enteredLine;
int leftStack, rightStack;
int leftQueue, rightQueue;
PalinedromeArray stack1 = new PalinedromeArray();
[code]....
Processing Queue Containing Dissimilar Messages
May 25, 2014I am new to Java/OOP in general, and am trying to implement a multi-threaded system that contains a master thread, and a set of worker threads that are heterogeneous in the work they do. Once they complete the work, the workers indicate to the master by posting the result on to its queue. Here is the problem. The results of each type of work is different, and the master has to process each differently. In C (which I'm familiar with), this can be achieved by having a message type that is a union of all the expected messages, and by using a switch statement.
I thought of doing something similar in Java, by using instance of on each incoming message (each individual message class having been subclassed from a super message class) , and doing switch on that, but it doesn't seem to be the OO way to do things. The only other way I could think of was to implement an abstract method to get the type of each message, and then use the type in a switch statement, or if-then-else. Is there some other Java idiom to do this kind of processing? Also, if this is an acceptable method, why is it superior to using the reflection to find out the message type (instead of using the abstract getType())?
The message types look similar to the code below:
abstract class Message {
abstract String getType();
} class Result1 extends Message {
ResultType1 content;
String getType() {
[Code] ....
Implementing A Thread-safe Queue
Jul 10, 2014I have situation where a user can request java server to send a value to an embedded device, and if the device is asleep, that value needs to be stored in a queue until the device wakes up and sends a position to java server, at which point the server checks if there is a value in the queue and if there is, it then sends that value to the device. The maximum size of the queue is 1 for now. And if the user makes continuous requests to java server, the old value is removed and the new value is added.
Initially I was looking into BlockingQueue, but the problem with that is, well, it blocks. queue.put(value) will block if queue is full, and queue.take() will block if queue is empty. I can't have something that blocks. When the device responds to server, server checks if value is in queue, if it is not then the server carries on the rest of its responsibility. Thus, I then entertained ConcurrentLinkedQueue. While queue.offer(value) and queue.poll(); allow you to add and remove values respectively from the queue without blocking, it does not allow you to set a maximum size limit of the queue. My queue must have a maximum size limit and it has to always be the newest value the user submits to the queue (where old values are removed).So this is what I came up with:
Java Code: class Unit {
private List<Integer> cmdQueue;
public Unit(){
cmdQueue = Collections.synchronizedList(new LinkedList<Integer>());
[code]....
I use Collections.synchronizedList, as I do here, do I still need to use synchronize as I did above?
Can't Get GUI Program To Print Out Queue List
Apr 11, 2014I have been working on this Java Gui program and i cant get it to print to the textbox correctly.i originally had it displayed in a dialog window but it would print one integer a time in a seperate window.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.lang.*;
import java.io.*;
[code]....
Changing Item Positions In A Queue
Nov 3, 2014So I got an interesting challenge today. I think logically I know what I have to do but I'm at a complete loss as for the actual coding implementation. So I have to develop this method called moveToBack(T entry). What this is meant to do is as implies, move entry to the back of my queue. As simple as it sounds, I know that I cant just move its position that simple. I know that I'll have to essentially remove whatever the desired value is, and then re-add it to the back of the queue. The interesting problem with this, however; is that I know that the FIFO property exists for queue's.
So if the desired entry to be moved is at the 3rd position of 4, I'd have to remove positions 1 and 2 to finally get to 3. But I want it to keep those values still. So I assume what I'll have to do is remove each element of the queue (it'll only be 5 entries max for the purpose of the project) and save it somewhere, then empty the queue and finally add the elements back in while waiting and putting the desired element to the last position.
If that's the case, I'm really curious on how I would do this. I have 4 files, 2 interfaces, the main class that contains the methods and what not for the queue, and a 4th class that'll be used for running test data and testing the methods of the program. Now, I wont add the interfaces code below because those are fine and all methods that need to be added are. I just gotta improve my moveToBack method so that it does what its supposed to. (I know I should have exceptions instead of my very poor else statements, but for this project it's not necessary.)
public abstract class NoDuplicatesQueueWilson<T> implements NoDuplicatesQueueInterfaceWilson<T>
{
private int MAX_QUEUE = 5; // Default array size, small for testing purposes
private T[] items; // The array of the queue.
private int front; // The first entered item of a queue.
private int back; // The last entered item of a queue.
private int count; // A counter.
[Code] ....
FIFO - Implementation Of Immutable Queue
Nov 12, 2014The following codes shows an implementation of an enqueue function of a FIFO immutable queue, and the output result shows the String "c". I don't understand why since I expected it should be null.
The head and the tail of an ImmutableQueue Object are two separate queue, and each time I call the enqueue function, it just return a new object with a new tail, however, the head is not modified except the first two times I call the function.
Therefore, I expected head.next.next should be a null element, but the result is not like that.
public class ImmutableQueue<E> {
public Queue<E> head;
public Queue<E> tail;
public ImmutableQueue(){}
private ImmutableQueue(Queue<E> hd, Queue<E> tl){
head=hd;
tail=tl;
[Code] ......
Queue Class And Java LinkedList
Sep 30, 2014I have a Queue class (containing a LinkedList plus a few other variables and stats for my project), which works fine with the standard LinkedList, but I'm trying to add my own code for MyLinkedList.
However, I keep getting a NullPointerException at my remove method.
public class MyLinkedList<T> {
Node head;
public MyLinkedList() {
head = null;
}
public class Node {
T contents;
Node nextNode;
[Code] ......
Finding Road With Stack Or Queue
May 2, 2014I have to make code about finding road with Stack or Queue. At first, I tried to make it in this way...
Java Code:
//public class QueueMain {
public static void main(String[] args){
int [][] arr = {{0, 0, 1, 0, 0, 1, 0, 0, 0}, //p
{0, 0, 0, 0, 0, 0, 1, 0, 0},//q
{0, 0, 0, 0, 0, 0, 1, 0, 0},//r
{0, 0, 0, 0, 1, 0, 0, 0, 0},//s
{0, 0, 0, 0, 0, 1, 0, 0, 0},//t
{0, 0, 0, 1, 0, 0, 0, 1, 0},//w
{0, 0, 0, 0, 0, 0, 0, 0, 0},//x
{0, 0, 1, 0, 0, 0, 0, 0, 1},//y
{0, 0, 0, 0, 0, 0, 0, 0, 0}};//z
String [] add = {"P", "Q", "R", "S", "T", "W", "X", "Y", "Z"};
int originnumber = 0;
int destinationnumber = 8;
[Code] ....
But it doesn't work at all. I tried to put visited address into array<mark>... but it didn't work.
Enterprise JavaBeans :: First In First Out Job Queue Processing
Mar 3, 2013I am looking for the ability, on the server side, to run programs or "jobs" in a job queue, where the jobs are processed as first in first out. If you are familiar with the IBM iSeries, they have a built in job queue mechanism which accomplishes what I am looking for. The primary purposes for this would be to process and update large amounts of data in a thread safe environment.
View Replies View RelatedCalling A Method - Return Smallest Value In A Queue
Nov 15, 2014I've created a getMin method to return the smallest value in a queue. However, I'm having trouble calling the method in my main.
/**
* Main method.
*
* @param args
* the command line arguments; unused here
*/
public static void main(String[] args) {
SimpleReader in = new SimpleReader1L();
SimpleWriter out = new SimpleWriter1L();
Queue<Integer> testQueue = new Queue1L<Integer>();
[Code] .....
Array Blocking Queue And Inundation Of Data
Jul 24, 2014I set the limit to 2 so the producer blocks after two insertions until an item is consumed. Because we are dealing with a basic counter that increments, we do not lose any data. Since after queue is freed up we simply increment by 1, so we are able to store all numbers. However, in real world situation, you might be storing data coming from redis server into the queue. And redis server may be publishing a plethora of data. So when the queue blocks, and new data comes in, what happens? Is the currently blocked data lost forever and the new data that came in is now blocked, or is the new data that came in ignored and the old data remains being blocked until queue is freed up?
Java Code:
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
public class BlockingQueueBlocking {
private BlockingQueue<Integer> sQueue = new ArrayBlockingQueue<Integer>(2);
int counter=0;
private void test() throws InterruptedException{
[code]...