Running Threads Without Using Runnable Implementation?
Dec 16, 2014
I've seen examples that don't use a separate Runnable Implementation, but Instead Just make a subclass of Thread and override the Thread's runO method. That way,you call the Thread's no--arg constructor when you make the new thread;
Thread t = new Thread(); 1/no Runnable"
Any simple code that demonstrates the same. I haven't fully understood what is said in the text above. I have a hunch that the last line is wrong and it should be Thread t = new <Whatever class extends Thread class and over rides its run method>()
When I try to run my runnable jar file, it wont do anything. And when I try to run it from the console, it says
"java.lang.UnsatisfiedLinkError: no LWJGL in java.library.path..."
How do I fix this?
I've specified the path by properties > Libraries > lwjgl.jar > Native Library Location > .... And I chose the right paths. But I still get that java.lang.UnsatisfiedLinkError.
It says I'm getting an error on line 34 which is:
appgc = new AppGameContainer(new Game(gamename));
My whole main class is:
package net.battleboy; import org.newdawn.slick.*; import org.newdawn.slick.state.*; public class Game extends StateBasedGame { public static final String gamename = "Battle Boy 1.0 ALPHA"; public static final int menu = 0; public static final int play = 1; public static final int settings = 2;
My app uses docx4J, XStream, and also uses an image on the start page. I placed all of this external libraries in Java Buid Path and in Eclipse it all works well but when I export all data to runnable jar file it doesn't work.
I am still working on my java course and now we have to create a jar file from a previous project (this is a project where a connection to the database is made and data is shown in a frame).
When I follow the instruction in my course material I don't get it to work. I've tried the following:
1. Open eclipse on windows xp 2. Right click on the project folder in eclipse 3. Click on "export" in the menu that appears 4. Choose "runnable jar" 5. click next 6. I insert the following parameters:
- Launch configuration --> I select my main class - export destination --> I select the folder D: - library handling --> Package required libraries into generated jar
7. click Finish
This is what happens when I dbl click the jarfile (wampserver is running):
1. I get an error: "SQL ERROR: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server."
2. I click ok on the message and the following message appears: "SQL Error: null"
3. I click ok on this message and the frame with the fields appears without data from the database.
my aim is to make a runnable jar. I've made a program using swings which uses MS Access database to fetch records. So, I've used an absolute path to refer to the database for connection. Now, I intend to distribute this runnable jar to other people as well. So I guess the best option would be to embed the MS Access database as well in the jar file. But I don't know how to do that. Where should I keep the database in my Project Explorer ? Should I use a relative path etc.
How does one use java.util.jar.JarOutputStream to create a jar file on button press? This new jar file, I want to make it runnable so it performs a specific action on run..
I want to have two threads running in my class, one will be downloading info from a website then putting the thread to sleep for a little bit, then repeating. The other will be sending information to a website then putting the thread to sleep for a little bit, then repeating. Is it possible to do this in my main class? I already have one thread using run() for downloading the info and sleeping can i make another?
I recently started working with Java 8. I have been doing Java development on and off since the early 1990's. Most recently I have been doing all my current work in Java 6. I decided to "take the plunge" and to start getting involved with Java 8. I have an imaging application for geologic research I started working on in Java 6 and Swing, and I am now continuing that development under Java 8. It was a pleasant surprise that to find that all of my code built without any changes (I'm using Eclipse Luna and just deleted the Java 6 runtime and added the Java 8 runtime after downloading it). The application launches fine from inside Eclipse.
However I ran into a problem when exporting the application from Eclipse to a runnable JAR file and then trying to launch it. After creating the runnable JAR I was not able to launch it by simply double clicking. A command line box would open for a second, then close and the application window would never open. To upgrade from Java 6 to Java 8 I only downloaded the Java 8 runtime environment, not the Java 8 JDK. I am working in Windows 7 and tried updating the JAR file associations and experimented with various path entries in my environment variables. No mater what I did I could not simply double click the runnable JAR to launch it.
Then I deleted all my Java downloads and started over. This time all I did was downloaded the Java 8 JDK and installed it. I then pointed Eclipse to the Java 8 runtime environment that was installed with the Java 8 JDK. My code built and executed perfectly in the Eclipse environment. Then I exported the the Eclipse project as a runnable JAR again and tried to launch it. This time it worked as expected. Double clicking the runnable JAR launched the application!
So my question is if I want to give this application to someone to run (i.e. deploy it) that is not a developer, do I have to have them install the Java 8 JDK? I assumed that all someone would need to run the application as a runnable JAR is the Java 8 runtime environment, not the JDK. However, when I had only the Java 8 runtime environment installed I could not launch the runnable JAR. With the Java 8 JDK I was able to run the runnable JAR as expected, with no problem.
I've been working quite a bit with a login system the past couple of months and I now have a version that I would like to try "for real" by extracting it as a runnable .jar or .exe file. I've looked at a couple of guides that told me how to do this properly, but even after following every step precisely it didn't work.
One of the guides I tried: 3 Ways to Create an Executable File from Eclipse - wikiHow
Double clicking the file or selecting it and pressing enter does nothing, the computer loads for a second and then nothing happens. I don't receive any visible errors when extracting the program, either.
However, when running the file from the command prompt I do receive an odd error: Microsoft Windows [Version 6.2.9200] (c) 2012 Microsoft Corporation. All rights reserved.
C:UsersUserName>java -jar Login.jar Exception in thread "main" java.lang.IllegalArgumentException: input == null! at javax.imageio.ImageIO.read(Unknown Source) at LoginSystem.Data.updateData(Data.java:347) at LoginSystem.Data.<init>(Data.java:309) at LoginSystem.MainFrame.<init>(MainFrame.java:42) at LoginSystem.MainFrame.main(MainFrame.java:457)
C:UsersUserName>
I must say I don't quite understand the error, it seems to be unable to load an image which is odd considering the program works fine without any errors at all in Eclipse.
I'm new to Java and trying to write code a Java program on Mac OS X using IntelliJ. My program uses the SWT library and contains two class's; the first called "view" and the second called "main". The "view" class defines the SWT objects, extends the "Thread" class and contains a "run" method;
public void run() { initComponents(); while (!display.isDisposed()) { if (!display.readAndDispatch()) {
display.sleep();
[code]....
I searched for a solution and saw that I have to use the "-XstartOnFirstThread" parameter to JVM. I'm trying it with no success.
I making a program that a client connect to a server, then it's starts changing information throw the socket. The info is String. When connection with one open client everything is working great. The problem starts when I connect 2 or more clients simultaneously.
The server doesn't know how to handle each request so it's send info to both the client info that is wrong. If I run several clients and then execute the last client that opens he will work fine the others will crush. On the server I'm getting connection reset. The problem i believe is with the closing socket and thread holding.
I have this web app in Glassfish which, among other things, monitors consultations in some DB. It's a JEE-EAR app, three layers. Pretty boring until now. Now, there's another WAR-app on Tomcat that processes files through threads. These threads represent an Excel file processed one row at a time.
I need to know when one of those threads are created, when they're alive and when they're terminated, from the Glassfish app.
I need to monitor these batch processes.
I think I could insert the thread ID from the tomcat app in some DB and when it dies, delete it. The glassfish app would query that BD and see if there is one of those batch processes running.
I understand that a thread ID can be recycled but I can find a way to make every process unique.
My first question, would this be viable?
My second question is, could I uniquely set the thread name and then ask for it from the glassfish app to the tomcat-app process thread set? I mean, without a DB in the middle?
Write a program to print the even numbers and the odd numbers between 0 and 30 using a single thread and then again using multiple threads.
I already finished the single-threaded program but am having trouble with the multi-threaded one. I have three classes; one class for odd numbers, one for even numbers, and one to execute the code. Here is my code so far:
Even Numbers:
Java Code:
public class EvenNumbers extends Thread { public void run() { for (int i=1; i<=30; i++) { if (i%2 == 0) { System.out.println("Even number " + i);
[Code] ....
Unfortunately, my output ends up looking a little weird:
Java Code:
C:UsersREDACTEDDropboxSchoolworkREDACTEDJava ProgrammingUnit 5 - Exception Handling, AssertionsProgram - Thread>java MultiThread Even Numbers: Odd Numbers: Even number 2
I'm reading the following section of the Oracle docs:
Guarded Blocks (The Java Tutorials > Essential Classes > Concurrency)
We have multiple threads. One of them sets the joy flag to true. The other waits until joy flag is set to true in order to print to the output stream. Rather than squander processer resources with a while loop, we choose to use the wait method of Object which suspends execution of thread. When the other thread throws an exception, we check the loop condition again.
Java Code:
public synchronized void guardedJoy() { // This guard only loops once for each special event, which may not // be the event we're waiting for. while(!joy) { try { wait(); } catch (InterruptedException e) {} } System.out.println("Joy and efficiency have been achieved!"); } mh_sh_highlight_all('java');
The documentation goes on to state the following:
When a thread invokes d.wait, it must own the intrinsic lock for d - otherwise an error is thrown. Invoking wait inside a synchronized method is a simple way to acquire the intrinsic lock. When wait is invoked, the thread releases the lock and suspends execution.
The statement seems somewhat contradictory. When we invoke wait inside a synchronized method, is the intrinsic lock acquired or released? I thought it was the synchronized keyword itself that acquired the intrinsic lock.
My multi threaded application processes and loads records into an ECM repository. For reconcliation purposes , I am trying to build an XML format report with the results of the processing per record, while processing is underway per thread. The method below is called from every thread wvery time its ready to append an element to the DOM with the status.
public void writeReportLine(Element rptLine) { // Write output to report file synchronized (XMLReportHandler.class) { reportOutput.getDocumentElement().appendChild(rptLine); } }
After all processing completes, the below method is called only once by every thread to write to the File on the file system:
public void writeToReportFile() { synchronized (XMLReportHandler.class) { try{ //write the content into xml file TransformerFactory transformerFactory = TransformerFactory.newInstance(); Transformer transformer = transformerFactory.newTransformer(); DOMSource source = new DOMSource(reportOutput);
[Code] ....
The problem is that when under load, the threads just seem to hang while the transformer.transform(source, result) call keeps getting executed until there is an interrupt of some sort. I was able to examine a section of what was appended and it was status for records that had finished processing very early in the process based on my application logs. Once an interrupt is recieved , it looks like the threads recover.
I created an instant messenger using java. When I have the Server that communicates between the clients and one client running on my Computer the CPU Usage is at 100%. It really slows down everything else I'm doing and I figure this might be an issue if I gave this to people to use. I don't want the client taking up a lot of CPU Usage if they're just running it in the background while doing other things on their computer. The program utilizes multithreading. Each thread is constantly being polled for input.
The Server, as seen below, has two threads. I explain what the threads do before the code. There is also another while loop running constantly in the server that is waiting for sockets to connect. The loop does not run constantly at the line socket.accept(); it stops and just waits.
The User, split into a menu and chat window, has two threads as well. I explain what the threads do before the code. After I originally posted I put a 100 ms sleep in all my threads. CPU Usage is still at 100%*
This thread listens for input from the user. The input tells the server what action to take. There is a thread running for every user currently connected to the server.
public void run() { try { input = new DataInputStream(user.getSocket().getInputStream()); output = new DataOutputStream(user.getSocket().getOutputStream());
I have a console application. One thread allows a user to directly input into a console. Another thread listens on a tcp port, takes input, processes it, and then writes it to the console. The work in different threads, but in tcp thread, one I call a method outside that thread that writes to console, it often gets stuck. here is a mockup of situation:
It often freezes on "Attempt 1". Before I used System.out there, I also tried console.writer() there but both freeze at that point often. Any situation where console or System.out.writeln freeze when working across threads and why it is occurring? It almost feels like one thread has locked the console so the others can't write to it.
I have been working on this program for a while and now i seem to be stump it throws an outof Bound array exception error, this program is a matrix multiplication program and spits out the resulting matrix using multithreading. i have a running one and result is
2 -1 0 1 0 3 -1 1 3
but this program's result is:
2 0 0 1 0 0 -1 0 0
it reads a txt document as an commandline arguement the text file reads just like this below:
3 2 2 3 1 0 0 1 -1 1 2 -1 0 1 0 3
the following is my code:
import java.util.*; import java.io.*; public class P3 { public static int matrix1[][]; public static int matrix2[][];
Actually, i want to create multiple ball using multithreading.I have created a class 'CreateBall' and this class is making ball and second class 'Balls' is a Panel where the ball is display.But only one ball is being displayed.
Here is my code.......
CreateBall.java import java.awt.*; public class CreateBall implements Runnable { int px,py; int w=20,h=20; Graphics g; public CreateBall(int px,int py)
Below are three classes. The first and second create car objects and the third is the main method. My goal is to move two cars across the window. When I compile and run the program both cars are generated however they will not animate. I am moving them with threads but I cannot seem to find why the cars will not move.
import java.awt.Graphics; import java.awt.Graphics2D; import javax.swing.JComponent; public class CarComponent extends JComponent { private Car car1; private Car car2;
