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.
I have a problem:I have a simple SWING program with buttons and I can't call "frame2.setVisible(true)" from ActionListener registered on a button. I don't understand, why the listener can't see "frame2".
import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.*;
public class test {
[code]....
I want to make a program that will move a square to the left if you press "a", and to the right if you press "d". (Once I know how to do this I can figure out W and S for up and down by myself). What code would I use for doing that? Here is the program I have now. I used the oracle tutorial but it just shows how to handle for if ANY key is pressed.
This is what I used How to Write a Key Listener (The Java Tutorials > Creating a GUI With JFC/Swing > Writing Event Listeners)
Java Code:
import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class myGame extends JComponent {
public int x = 20;
public int y = 20;
[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]....
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 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 have a Jbutton in my application named as SUBMIT,on clicking SUBMIT the text of jButton changes to ABORT. I wish to apply enter key listener on both the SUBMIT and ABORT button in my applcation, however I am not able to get the text of the button in key listener,so that i can apply my code based on the current text of Button.
View Replies View RelatedI wanted to create a interface with buttons ofshapes and type of transformation where user first select a shape, the shape will appear and user will have to click on the buttons on resize, reflect, rotate or skew to transform to shape. How can i do the coding? such as adding listeners to the shapes?
View Replies View RelatedI have panel = window(new frame) and its used to render a video image on, i need to pickup a touchscreen press change of event but not sure which event listener to use and on which component. Is it a panel, window or frame event? and which listener would detect a focus change or a mouse press
I know mouse listener and focus listener and window listeners are available but not sure they would be able to detect the screen press on the video rendered image...
am trying to create a mouseListener that when you click a tile and drag in any direction it has to collect all the letters in the tiles that were dragged over and save to a stringBuilder. I have everything working its just this last key issue related to mouseDragged that has me stumped. Iv searched countless websites but am still unable to find anything that is remotely close to what i need.
View Replies View RelatedWhenever i click start button it will just printout start to the jtextfield it wont start the time .
import java.awt.*;
import java.util.Date;
import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.*;
[code]...
The program i am creating consists of two JPanels (currently) and one canvas. The canvas is in the center of the JFrame, while flanked by JPanels where both have 13 buttons each.
To paint a simple picture, my program will draw letters on the middle canvas when a button is clicked.
I created my own buttons that implement the ActionListener interface , so when a button is clicked it will display its character in the console. But my question is, How do you implement the listener to draw something on the Canvas when the button's are clicked?
I'm using Eclipse with the Window Builder Pro plugin to create a Java program. I noticed that when I had Eclipse create an action listener for a combobox in a Swing GUI it created an AWT listener.
Did I choose the wrong type of listener? I want my code to use the Swing components because I understand that they are more portable.
Couple of problems here...
1. I am trying to use the getSource method in my inner class, in order to set the JPasswordField within an Inner Listener Class. This is a 4 integer password, setup by my for statement in the loop. I know what I want the program to do, but I don't know the correct language to use. I want the user to press one of the keys (0-9), that value be stored in JPassword (at least I think that is how it works) and for it to display the "*" in the Field---I want this to loop 4x. How do I use the getSource() to do this.
Also, I believe I need to use the set and get methods for the password entered into the JPassField, is that correct? The inner class is not recognizing my the object password that represents the JPasswordField.
2. In my second Inner Listener Class, clearButton, I set the event.getSource method to reset the JPasswordField to " ", when the clear button is pressed. Again, the problem is that the inner class does not recognize password. Why is this the case, since it is still a part of the parent class Atm?
Java Code: import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Atm extends JFrame {
Atm(){
super("ATM");
int i = 0;
//Create Panels For ATM
JPanel buttonPanel1 = new JPanel(); //To Contain Digits 1-9
buttonPanel1.setLayout(new GridLayout(4, 3));
[code]...
I 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'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 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 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] ....
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> {
public Queue<E> head;
public Queue<E> tail;
public ImmutableQueue(){}
private ImmutableQueue(Queue<E> hd, Queue<E> tl){
head=hd;
tail=tl;
[Code] ......
I 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] ......
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.