I 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.
Implement a priority queue based on a sorted linked list. The remove operation on the priority queue should remove the item with the smallest key.
View Replies View RelatedI 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?
I 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?)
I'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.
My 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.
I 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...
This was shown in class the other day and I'm still not sure of how exactly it works, even after looking at it through a debugger.
public void sort(){
for (int i = 0; i < size; i++) {
Node temp1 = head;
Node temp2 = head;
Node temp3 = head;
while(temp2.next!=null){
temp3 = temp2.next;
[Code]...
Again, I didn't write this code I'm just trying to understand it. Why specifically do three different temp values need to be used instead of just one like in most sorts?
It is part of a larger program that can be found below.
import java.util.Random;
public class MyQueue implements IntegerQueue{
class Node{
Node next;
Integer data;
Node(Integer data){
this.data = data;
[Code]....
I am trying to find a concise way to write the sort methods for my class. I am supposed to make a program that can sort objects by a number of fields: year, rank, artist and title.
I used an idea from this thread : java - Sorting a collection of objects - Stack Overflow
And I am trying to use the custom comparator for my sort methods. However for some reason, the sortingBy variable fails to recognize any of the enum types.
Whenever I try to set the sortingBy variable equal to one of them, for example:
Java Code:
private Order sortingBy = Year; mh_sh_highlight_all('java');
I get a "Year cannot be resolved to a variable" error.
What I want to be able to do is make it so every time a specific method is called, say, for example sortTitle(), sortingBy will change to Title, then the SongComparator will sort using the case Title.
Is it possible to do this? I can't figure out how to modify SongComparator's object variables that way.
Java Code:
import java.util.Comparator;
public class SongComparator implements Comparator<Song> {
public enum Order {Year, Rank, Artist, Title}
public Order sortingBy;
[Code] .....
An array has objects with String firstName, String lastName, int ID, char examType('M' or 'F'), and int score. Every object has both Midterm('M') and Final('F'). The array has to be sorted by the first Midterm- 'M' and immediately followed by the Final ('F') of the same person (object). Im having troubles with coming up with a proper algorithm with gettin the Final- 'F' after Midterm for the same person.
Java Code: public static Exam[] collateExams(Exam[] exams) {
Exam [] r = new Exam[10];
r = exams;
int[] position = new int[10];
int index = 0;
for(int i = 0; i < exams.length; i++)
[Code]...
I have a requirement to find the greatest/maximum of the given list of Calendar objects in Java.
i.e., 2013/01/26
2014/03/03
2012/02/27
2014/01/15
So the above list of calendar objects are in Arraylist. I need to get the max/greatest among these. Eventually, the answer should be 2014/03/03
I have to create a method with the following header :
public static <E extends Comparable<E> > void sort ( ArrayList<E> list , int left, int right)
i also had to create a swap cells method and position of max integer method. and also had to read the preserved data file in with a scanner. I implemented the comparable interface I am having difficulty sorting my list by the area. It has to be in descending order.
Geometric Object class: since it has comparator also am interested if i need to change this?
CODE:
Driver:
public static void main(String[] args) throws IOException, ClassNotFoundException {
Circle c1 = new Circle (4, "red", false);
Circle c2 = new Circle (2, "blue", true);
Circle c3 = new Circle (10, "blue", true);
Rectangle r1 = new Rectangle (10, 6, "yellow", true);
Rectangle r2 = new Rectangle ( 5, 11, "green", true);
ArrayList <GeometricObject> list = new ArrayList();
[Code] ....
I have a school assignment that involves me sorting an array of objects based on one of the class String variables. I am using as the title says a simple selection sort method. The problem I'm having is that when I run the program in debug mode, it never seems to enter the if statement in the inner loop. I would like to say I've tried a number of things to figure it out, but honestly I'm just stumped as to why it's not working.
Here is the code:
public static void sortTransactions(Transaction[] oTransaction){// This is the sorting method, obviously it's not done so it currently just prints to screen.
System.out.println("Successful call to sortTransaction()");
String min = "";
int curInd = 0;
Transaction[] temp = new Transaction[1];
[Code] ....
The output when I check to see if the array is sorted verifies that the array never does get sorted.
So 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] .....
I 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.
I am currently working on a project where I need to return data from a database over RMI to a client who requests it. Some of the fields in the Data Object can not be seen by the client so I need to create another object to send over the network instead. The method I use is this...
public static SerializableObject createSerializableObjectFromDataObject(DataObject dataObject){
SerializableObject serializableObject = new SerializableObject();
serializableObject.setField(dataObject.getField());
serializableObject.setAnotherField(dataObject.getAnotherField());
return serializableObject;
}
Is there a better way of doing this? I am creating many subclasses DataObject which all require this static method to be implemented and I can't push it into the superclass because each one needs custom behaviour.
Is 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.
leaveQ 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]....
I 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]....
implement 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]....
The 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] ....
I'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]....
I 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] ....
I 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?
I 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]....
So 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] ....