My java application is blocking from time to time. I have added some log lines and now I know exactly where is blocking, but I have no solution to fix it.
This code runs in a parallel thread, distinct from the main application thread and updates a big JTextArea swing:
try {
....
JTextArea element = (JTextArea)add_containers[objColIndex];
System.out.println("setEditValue start seting text ");
element.setText(VAL);
System.out.println("setEditValue text is set ");
[Code] ....
The code reaches "setEditValue start seting tex" but never reaches "setEditValue text is set". No exception is triggered. The whole application is blocked - main thread and this paralel thread. This section of code is called many times, but in rare cases is blocking without any apparent reason. Sometimes I run the exact same instructions and is blocking and sometimes is working.
I'm just starting up with Java Mulithreading.Below is the repo I set up, and I am having trouble with this test I am doing playing around with Executor threadpools. I am trying to setup a managed system where I first add some lines to be printed, then add the work to the work pool, and then finally launch n number of threads to handle the work (or in this case, print out the strings I added to WorkManager instance fields). I watched this series of videos starting with this one: URL...., and I planned on playing with the concept of multithreading, but it doesn't seem to work and gets stuck at Thread1:27. I thought that by synchronizing access to the ListIterator return, that it would not block. URL....
I 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{
convert or move standalone java thread application into Tomcat server container for accessing its JNDI services? Also is it possible to schedule this thread application in Tomcat server? is it possible to keep this app in tomcat as web application and schedule in window's scheduler.
Me and my brother decided to make a relatively simple client/server program where clients get into a simple chat lobby and can invite others to play small games(like pong). The basic server code has been written, and we have made a special client that is used for debugging.
We use a self-defined protocol of Strings where a message looks like "4-|user,pass". The number before the delimiter "-|" is the operation code, that tells the server what kind of message this client sends. Based on that number, the server dispatches the message to the appropriate handler method. 4 is authentication for example, and the handler looks the user and pass up in a file and if found, returns true, otherwise, false. Then the server responds to the clinet with 2-|"any message" where the client will recognize opcode 2 as a "authentication accepted" and proceed with the next part of client code. In a similar way, we plan to write all message types(both in the game, in the lobby and in a game setup room).
While testing we ran into a problem where the BufferedReader .readLine() does not seem to be a blocking call like it should be, so the client keeps spamming 'null' in the output field that we made to see the server response to the message we send. When we try to debug the server code and set breakpoints at the suspicious locations, it strangely skips both while(true) loops without activating either breakpoint and executes the finally{} code, even though the client did not close the connection and the second while loop was never entered. The first while loop IS entered though, because the test client gets a "0" on its output, which is the server message indicating "please authenticate yourself".
We decided to use messages in a string format and decode it at both sides as it seemed easier than transmitting java objects and making sure they are of the same type, also for reducing overhead as much of possible.URL....
I have tried running the java application without adding the site to site list in java security tab. But I get a sand box message as APPLICATION BLOCKED BY SECURITY SETTINGS. How to run the java application without adding the site to site list in java security tab.
I've written a java application with several classes all in the same .java file. It works just fine. Now, I've broken it up so that each class has its own .java file. Still works fine. My next step is to put those classes into a package, but I'm not about to get the program to run.The .java source files are all in /home/user/src
I've set the CLASSPATH to /home/user/src..All of the source files have "package com.myfirm.program" on the first line.I compiled the application with:
the compiler created the directory: /home/user/src/com/myfirm/program and put all of the .class files in there.So how do I get the program to run? if I run from /home/usr/src
java File1
I get: Exception in thread "main" java.lang.NoClassDefFoundError: File1 (wrong name: com/myfirm/program/Program)
A while ago, I developed an application in VB.net, and I'm trying to "convert" this application to Java. But this VB.net application uses some specific DLLs and I need to use them in my Java application. However, my knowledge in this respect are quite limited in manupulate DLLs on Java.
Up to this point, I can already load the DLL. I've read some documentation on how to use functions that are in the DLL; but I have some doubts. For example, how can I translate this piece of code to Java?
Java Code:
API = New MyDLL.Base With API .para1= "1" .para2= 2 .para3= True .para4= False
I am currently faced with a task of creating a web application. This application is meant to be accessed by an admin and also a customer. On the customer side the app should prompt the user to fill in an application for of sort and also allow the user to upload a CV to a database. The information entered by the customer will also be saved on the database. The admin should have the ability to look through all the candidates and their information and CV`s. He should also be allowed to search for candidates with specific key words...I am not a professional programmer but know the core of Java programming. I have a tiny bit of knowledge of MySql.
So say I write up a program like a dice roll game, which I see on the forums here. It's all written and good to go and when I hit Run it does what I want it to do, no errors..What do I do with those .class and .java files? Do I compile it somehow into an app I can put on the google play store? What is the NEXT STEP after the program is all written?
I am creating a free game in java FX and I would like to offer some advanced features for the supporters (a user of the application that donates to support the project).
But I dont know how to authenticate the user to some network service.i would like to have a hosted application (or light framework) accessible through the network so the user can do something like login with posting credentials (email, password and maybe his IP adress - so I can check if he has passed his credentials to someone else) and to be able to manage the service to add, remove, (un)block users.
I dont know if I should try to create an authentication app myself, as it seams it shouldnt be as hard as I have no roles, no authorization, just a simple authentication. I would like to host it somewhere for free, than maybe if it will be succesful a want to have my own paid light hosting.
I looked for some frameworks, like Apache Shiro, but i would like to know what are the approaches in this kind of donating user authentication, before dwelling into some framework for months just to realize that it is not what I want.
Is there a way to make a exe file, with all dependencies included so it is possible to run the application on any computers without installing any other programs?
I have written a java application that retrieves data from a database and display it on a graph. What i want is that the two systems are synchronized in such a way that when we update a value in the database, it is immediately shown on the graph.i have tried to use a refresh button but decided this would increase the overhead.
I am following a tutorial to write a 2d game from scratch in java but when I compile and run my code the application (JFrame) doesn't come up on my screen, it just runs for a second and terminates itself for some reason.
package com.thecherno.rain; import java.awt.Canvas; import java.awt.Dimension; import javax.swing.JFrame; public class Game extends Canvas implements Runnable{ private static final long serialVersionUID = 1L;
2.localhost:8080/Workflow/admin/EditReport Form action is EditReport(Servlet Name).
Now on EditReport i perform the databse operations and forward the request to the GetReports?fname=Formname Servlet using Request Dispatcher.So that i am on the same page which is the first one (1) i started from.
Now Everything works fine on the .jsp page But the url remains unchanged that is the second one (2).
Now if i hit the URL again i.e. localhost:8080/Workflow/admin/EditReport it will give an error.
So how to rewrite the url i.e. from admin/EditReport to /admin/GetReports?fname=Formname after performing all the operations.?
Create a Java Application in NetBeans with the following two classes.
1. A Java class College o Use the following data fields: College Name College City Number of Tracks Number of Students Number of Faculty Number of Staff o Implement an empty constructor o Implement a full constructor o Implement Setters and Getters (Mutators and Accessors) o Implement SetAll() method with all data members as parameters
2. Another Java class called CollegeDemo with the main() method: o In the main(): o Read the values of the fields of 3 colleges from a text file and for each create a College object. Filename: colleges.txt IT Dubai 7 200 50 20 ENG Abudhabi 4 400 60 20 SCIENCE Sharjah 3 300 40 20 First with empty constructor then uses setters. Second with full constructor (no need to use setters). Last one with empty constructor and SetAll() setter. o Display the average number of students for all the 3 colleges. o Change the value of ‘Number of Students’ in the SCIENCE College to 500, and display the average number of students again.
here my code :
public class Demo { private String name ; private String city; private String cname ;
How to insert and play a video or a music background in a java application. Let me explain better... I need to develop a game where sometime I need to show picture, or play videos and also, if is possible, add a music in background... I work with eclipse and I know quite good the main concept of java's language...
how to develop a CHAT APPLICATION using Java springs .this should be very simple client server project with rich front end IT contains login page and a chat page.
I am developing an application using Java Swing on Netbeans using Java DB, In which i want to create a form using Jtextfields & JComboBox.
I already added data in the JcomboBox to select. I already create a database and table for this application. Now i want to insert the data in Jtextfield and selection of Jcombobox to insert into the table i designed for it. How to link the form with the table and insert the data of form in table...
