Creating Task Manager Using Java
Dec 5, 2010I want to create a TASK MANAGER for windows OS using java. Of course i am not expecting any code snippets, that is, what are the classes to be included and moreover HOW to do it.
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Scheduling A Task Every Month In Java
Feb 22, 2015I am new to Java , Every 5th date of every month , get 10$ in bank account .
View Replies View RelatedEJB / EE :: Long Running Task Processing In Java
Feb 18, 2014I want to develop a Java EE application for the following scenario.
Webapp takes a file from a user and analyze the file. This analysis could take hours. User should be able to check if the analysis is finished via AJAX. When the analysis is finished user should be able to view the analysis report that has been generated by the analyzer.
I checked what are the possibles ways I could achieve this but couldn't get a clear idea. I heard about JMS, Work Manager API and servlet asynchronous processing. But still not sure what to use and how to use.I'm not very much familiar with EJB.
Servlets :: Perform Certain Task On Shutdown Of Web Application In Java?
Apr 5, 2014how to perform certain task on the shutdown of a web application in java
View Replies View RelatedJava Code Using Timer Class To Schedule The Task
Feb 27, 2014I have written the java code using timer class to schedule the task , but i am getting error as } expected, i am not able to figure out the error, I have placed the { opening and closing curly bracket everywhere but still it is giving me error.
mport java.io.*;
import java.io.FileInputStream;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
import javax.mail.internet.MimeMessage.*;
import javax.mail.internet.InternetAddress.*;
[Code] ....
Use GridLayout Manager To Arrange Buttons
Dec 5, 2014Create a frame with ten buttons, labeled 0 through 9 (Hint: You may create an array of 10 buttons). To exit the program, the user must click on the correct three buttons in order, something like 7-3-5. If the wrong combination is used, a JOptionPane message ““Wrong, try again.” will be displayed. You may use GridLayout Manager to arrange the buttons nicely. My coding :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Combination extends JFrame
{
private JButton[] numbers= {new JButton("0"),new JButton("1"),
new JButton("2"),new JButton("3"),
new JButton("4"),new JButton("5"),
new JButton("6"),new JButton("7"),
new JButton("8"),new JButton("9")};
[code]....
Ok so I don't have any error in this. Only issue I have is my loop goes infinite. I can click on any numbers. I want to limit it for upto three numbers and if they are wrong output as wrong numbers. and If they press right number I want Correct number as output.
EJB / EE :: Web Application Entity Manager And PreparedStatement Functionality
Feb 14, 2015Am trying to develop a web application, and am using the Entity Manager. The web application involves users posting data to the database. How do I incorporate the entity manager together with the prepared Statement functionality to avoid users corrupting the database with SQL tags?
If I have EJB database session beans, when the content of the database changes, does the information on the web page get automatically updated dynamically on the client machine?
Swing/AWT/SWT :: How To Drag And Drop Component Within Layout Manager
May 28, 2014For example, say I have I BoxLayout with a few JButtons in it. How could I make it such that I could drag a JButton such that it could be in front or behind the others?
I've thought about using ComponentMover and just switching to a null layout right before moving it and switch it back right after like bellow, but I'm not sure how to make it keep the change in order.
import java.awt.LayoutManager;
import java.awt.event.MouseEvent;
public class LayoutComponentMover extends ComponentMover
{
private LayoutManager layout;
[code]....
Read File From LoginModule Running Under Security Manager
Nov 27, 2013I have followed the Java tutorial on JAAS Authentication and Authorization. All the sample code in the tutorials works fine also when running under a security manager. Now I am trying to modify the LoginModule class, so that it uses a password file to look up users and passwords, but as soon as I try to run the code under a security manager, I get a Security Exception. I suppose it has something to do with the code havent been granted any access to read the password file? So I tried to add this to the policy file:
grant codebase "file:./sample/module/-" {
permission java.io.FilePermission "sample/module/passwords.txt", "read";
};
It didn't do any difference. why I get this Security Exception?
The only difference from my code to the tutorial code, is that I have added the lines:
Scanner scanner = null;
try {
scanner = new Scanner(new File("src/sample/module/passwords.txt"));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
to the login() method of the SampleLoginModule class...
Football Manager - Find Out Optimal First Eleven Amongst 25 Or 30 Players
Nov 26, 2014I am looking into making a program, that will find out the optimal first eleven (in football or soccer for americans) amongst 25 or 30 players. This is going to apply for a computer game: "Football manager 2015"
I was thinking one class would be the player class that is going to have the variables:
player_number (unique) integer
name string
position (there are eleven positions)
position_rating for each position capable of playing
constructor would be add_player(int number, string name)
and a method would be add_position(position, position_rating)
one player can have more than one positions
another class would be the position
position name (unique) string
that's all I can think of now.
the main class would do a loop
starting with a random or defined position it would do all combinations of every single player into each position.
For example it could start with center forward position. There are 5 available players for that position. Lets say the program picks the first player that is also capable of playing in wide position. If the player is picked for center forward he is not avaialable for wide position.
Then the program would move to the wide position and lets say there are 4 players available. It would pick one.
Once 11 players are selected it would add the 11 ratings.
and start over for a different player in center forward position.
at the end of all loops it would print out the 11 players into their respective positions that got the best score.
Enterprise JavaBeans :: How To Use Application Managed Entity Manager In EJB
May 9, 2014I finish reading The EntityManager Interface in JEE tutorial. I know I can use container manager entity manager in EJB, but I want to explore how to use application managed entity manager in EJB.
Can I use application managed entity manager in EJB (container management JTA transaction is used)? Where do I should close entity manager if can?
The following is an example from JEE tutorial, but didn't find where to calose entity manager. and can I create mutiple EntityManagerFactory objects and Entity Manager objects to use them in a JTA transaction?
@PersistenceUnit
EntityManagerFactory emf;
EntityManager em;
@Resource
UserTransaction utx;
[Code] .....
Automate Web Task
Jun 26, 2014Since musicians are supposed to use ALL free services available to them in order to promote themselves, every time we book a show I have to: update facebook, update reverbnation, update bandcamp, etc.
So I was trying to find a way to automate this task, and I found a way to output my facebook page's events to an ical file (which I can port into Google Calendars if I wish). ReverbNation and Bandcamp unfortunately don't offer any integration with anything at all period... So this is what I wanted to write some code to do (see flowchart thing).
Enterprise JavaBeans :: Does Container Managed Entity Manager Is Thread-safe In Stateless Session Bean?
May 8, 2014I read JEE6 doc and confused with : Does container managed entity manager (injected by PersistenceContext annotation) is thread-safe in stateless session bean in multiple-thread env?
See code below, if there are 2 requests to stateless sesion bean in 2 concurrent threads , is it using same Entity Manager Instance or not?
@Stateless(name = "HRFacade", mappedName = "HR_FACES_EJB_JPA-HRFacade-HRFacade")
public class HRFacadeBean implements HRFacade, HRFacadeLocal {
@Resource
SessionContext sessionContext;
@PersistenceContext(unitName = "HRFacade")
private EntityManager em;
[Code] .....
JSP :: Windows Schedule Task Dashboard
Jun 5, 2014I want to create a Web page which can monitor and display the status of Schedule Tasks setup on different remote machine. This Dashboard should also has the capability to re-run the schedule task.
I know that I can achieve this via Runtime class by running schtasks /Query and get all the details. But I just wanted to know if we have any other better way to do this.
JavaFX 2.0 :: Using Task And Service To Read From And Write To GUI
Aug 8, 2014I have a database of 100,000 research articles, all as full text. From a GUI I'm building ( w. Scene Builder and NetBeans) I would like to enter a journal name and have some of the articles read into memory, in a background thread. Then I would analyze them, also in a background thread. Then I would write various results, e.g., lists of authors or titles, wordlists, to the GUI for examination by a user.
How to create background threads from my model that will read from and write to a GUI using Tasks and/or Services.
How Does Threads Come Back To Ready State After Executing The Task
Mar 21, 2014When a thread completes its execution, it will be destroyed.In Java thread pool implemenation, how does threads come back to ready state after executing the task.?
View Replies View RelatedServlets :: Setting A Timer Task Even If Server Restarts
Jun 10, 2014I have a web app that accepts requests. Once a request is sent, I want to create a thread that will sleep for several days if no user action is taken on the request to remind the user to do something. The problem is, how do I ensure the timer will pick up at the same place if the server is restarted? Would serializing the thread do that? I'm guessing no because I think you're just creating a new instance at start up. Just checking If there's anything built into Java to do this.
View Replies View RelatedSwing/AWT/SWT :: Simple GUI Task - Draw Pie Chart With Different Colors
Jan 31, 2014Simple gui task. it meant to draw pie chart with different colors. i can't seem to find a mistake in it. It works if i put in g2g.draw(arc) i know arcs overlaps a bit due int conversion, but that's ok.
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import java.awt.geom.Arc2D;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.Color;
[Code] ....
Interface Task - Manipulate Entries In A Telephone Directory
Feb 19, 2014Write an interface Directory to manipulate entries in a telephone directory for the University. The interface must support the following operations:
1) The ability to insert new entries into the directory. Entries should be stored in alphabetical order of surname.
2) Delete entries from the directory either by name or number
3) Provide a lookup method that will find the extension no of a member of staff given his/her name. You should try to make this method run as efficiently as possible.
4) Change a person's telephone number
5) Print the telephone directory in a neatly tabulated fashion.
Write a class ArrayDirectory that implements this interface using an array to store the telephone directory information. The class must store the surname and initial for each member of staff and their telephone extension (a four digit number which may start with a zero). You may find it useful to define a class Entry to store information about individual entries. The entries should be read into the array from a text file consisting of multiple lines in the following format:
Surname<tab>Initials<tab>Telephone extension
Write a main program that reads in data from a file and then tests all the methods of your class interface. Note it is not necessary to write data back to disk (even if it has changed) in this project.
For data insertion and lookup, you should measure the performance for the average case (e.g. looking up a record in the middle of the data). To do this you can use the static method System.currentTimeMillis() which returns the time in milliseconds. To get an accurate measure of the time to perform an operation it is a good idea to perform each operation 1000 (or even 10000) times and measure the time taken. This will remove any problems due to the system clock having a coarse granularity (not ticking very often). Make sure you only time the method and not any input/output associated with it. Your documentation should include a discussion of these results.
Part 2
You decide that your solution to part 1 may be too slow to be useful when used with a real large telephone directory and make the following changes to attempt to improve the performance of your program:
1). Provide a second implementation (ListDirectory) of the Directory interface using the Java Collections List interface and LinkedList classes.
2). The changes in 1) should make adding, deleting and modifying records more efficientbut will probably reduce the time to lookup numbers. To overcome this you use a technique called hashing. Instead of storing all the records on one list you use a series of lists. The data for all people whose surname begins with "A" is stored on the first list, records for all people whose surname begins with "B" on a second list and so on. Write a third implementation (HashDirectory) of the Directory interface using this technique.
Again, you should measure the performance for the best, worst and average cases of implementations 1) and 2) above. Compare the efficiency of each of the 3 implementations in your documentation.
Part 3
Choose one of your 3 implementations from Parts 1 and 2 and embed it in a graphical user interface that allows users to perform all the methods in the Directory interface using a mouse and keyboard appropriately.
Servlets :: How To Implement A Callback Method For A Post Async Task
Mar 26, 2015I am developing an app with a Java Servlet backend, and I am trying to get the Async call (AsyncTask - Android Developers) to get my response message Synced with the rest of the client and being able use this information wherever I want. Without a callback method, when from the caller class I use the commands:
ServletPostAsyncTask s = new ServletPostAsyncTask();
s.execute(new Pair<Context, String>(ListViewPrenota.this, "tours"));
Tours ttours = s.tours;
Tour tour = ttours.getTours().get(0);
I receive a NullPointerException pointing to the third line Tours ttours = s.tours;, since the s.execute() method doesn't wait for the rest of the lines to get executed.To solve this I thought about implementing a callback method with interfaces in Java, but I am not sure on how to do it. For example, what class does have to implement the interface, the ServletPostAsyncTask or the caller class?
Swing/AWT/SWT :: Disable Event While Performing Long Running Task
Apr 28, 2015I have in my application a button that when it is pressed, runs a long running task (usually takes a couple of seconds....).
My problem is that while the task runs, I want to stop the button from receiving clicks. Unfortunately this is something I have not achieved.
I have tried creating a new thread and calling the long running method, and using the Display.geCurrent().asyncExec...
Examples of what I have tried so far:
myButton.addSelectionListener(new SelectionAdapter() {
@Override
public void widgetSelected(SelectionEvent e) {
if (myList.size() > 0) {
myButton.setEnabled(false);
myButton.setGrayed(true);
[Code] .....
In both cases, while the button is disabled and the cursor busy, if the user clicks the button, the long running method is ran several times - and this is what I want to avoid.
Creating A Tree In Java
Sep 9, 2014how to create a tree data structure in java.I tried with a class consisting of node field and arraylist child nodes. but it does not satisfy the requirement.the requirement is that,
root: child1,child2,child3
child1:child4,child5
child2:child6,child7
on traversing it should print all the nodes as given above.no node should have same elements as child.
Creating Rectangle In Java
Apr 16, 2015I have a problem with creating a rectangle in Java. When I create the first rectangle all is ok. But the next, is the problem.
View Replies View RelatedCreating XML File In Java
Jul 30, 2014I'm getting a DOMException, "HIERARCHY_REQUEST_ERR". I know that the problem is from the following code towards the bottom in my function, but I don't know how to deal with it. When I get rid of doc.appendChild(staff);, I get rid of the problem, but it obviously doesn't add the new entry to my root element.
Element staff = doc.createElement("Staff");
doc.appendChild(staff);
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
[Code] .....
CheckerBoard Won't Appear - Creating A Game In Java
Mar 8, 2015Anyway I am creating a game for my A2 coursework, most commonly known as Checkers. I have completed my code and everything works as I had planned except that the CheckerBoard itself as well as the checkerpieces do not appear to be showing.
The section of were my board should be present is just a black space. Although my board does not appear to be displaying, all of the actions I perform on it such as clicking certain section produces the planned response, and although I've checked through my code I cannot work out what I've done wrong.
CheckerBoard content = new CheckerBoard(); // Sets the CheckerBoard values into the content to be used in the next line
application.setContentPane(content); // Container holds the values together, Content pane of the CheckerBoard
application.pack(); // Use preferred size of content to set size of application.
Dimension screensize = Toolkit.getDefaultToolkit().getScreenSize();
application.setLocation( (screensize.width - application.getWidth())/2,
(screensize.height - application.getHeight())/2 );
[Code] ....
I have noticed is that within the BoardComplete(), if you change the setBackground(Color.BLACK) to WHITE, it will change the colour of the section to white, but the checkboard is still unshown.
Creating Java Linear Algorithm
Oct 13, 2014I'm finding common elements in a collection of arrays. This is my code so far.
import java.util.ArrayList;
import java.util.List;
public class CommonElements //< T extends Comparable<T> >
{
Comparable[] comparable;
Comparable[] tempArr;
Comparable[] tempArr1;
Comparable[] newArray = new Comparable[tempArr.length];
int comparisonCount;
[code]....
I'm using this method to sort through my array. The method accepts a collection of arrays (of varying length and of any type) as input, the algorithm input should be no greater than n(k-1). I know I can solve it using a quadratic algorithm, but it won't meet the requirement of the assignment. I did have an idea of storing all my algorithm in one giant array. After storing as one giant array I was going to sort it. After sorting I was going to compare each array side by side and see if they are the same. Here is note my teacher provided.
Note About Testing You will need to develop several sets of test collections for testing your algorithm. The grading rubric mentions covering the case where all the test collections have the same length, as well as covering the case where the test collections are of different lengths. You will also need to think about what constitutes the worst case scenario for this algorithm, since only that scenario will make your analysis of total comparisons performed a meaningful one. You can use the formulas in the grading rubric to tell you how many comparisons you should expect in the quadratic and linear cases. For example, if you have 5 total collections (1 query collection and 4 test collections), each of which contains 10 elements, the total number of comparisons performed in the worst case should be: (k - 1)N2, which for k = 10 and N = 10 is: (5 - 1)102, or 400 comparisons. For the linear algorithm, you should only have N*(k - 1), which is 10*(5 - 1), or 40 comparisons.
Here is Q/A that my teacher provided:
1. Are the elements in the collections already sorted?The input collections may or may not be sorted. Don’t assume that they are sorted.
2. Can I sort the elements in the collections? Am I supposed to sort the elements in thecollections?Yes, you can sort the elements in the collections. It is not required that you do so, however..
3. If I sort the collections, should I count the element comparisons that are performed by the sorting algorithm?No. The only element comparisons you should count are the ones that are directly used to find the common elements. Ignore comparisons performed by any sorting algorithms you use.
4. How do I extract an individual collection from the Object[] collections argument of the findCommonElements method?You will need to typecast each collection as type Comparable[]. For example:Comparable[] currentCollection = (Comparable[])collections[i];
5. Why are we using a one-dimensional Object array instead of a two-dimensional array of type Comparable (e.g., Comparable[][])?In Java, arrays are treated as objects, so only a variable of type Object[] can contain arrays. A variable of type Comparable[] can only contain Comparable elements, not arrays. A variable of type Comparable[][] also can only store Comparable elements. Although it is possible to organize the elements such that all the elements at indexes [1][i], for example, are considered to comprise a collection, this is not the same as having an array that contains other arrays. The additional bookkeeping is required to keep a 2D array organized is more complex than simply performing the typecast described above.
6. Can I use other data structures besides arrays; e.g., HashMaps?No. Although it is easier from a programming perspective to use higher order data structures like HashMaps to find common elements, using these structures simply hides the details. If you were to examine the implementations of those structures, you would probably find that they use relatively inefficient algorithms such as sequential searches to find elements. Additionally, if you use library components, you have no way of counting the number of comparisons performed, since you don’t have access to the source code of those components.
7. Is this a trick question? I can’t think of any way to get below NlogN comparisons.It is not a trick question. It is possible to solve this problem using a number of comparisons proportional to (k – 1) * N.