I am working on a GUI application that uses JavaFX(not fxml) and exported as a JAR. For slow machine, impatient user click more than once on JAR, and multiple instances of application started.
I'm looking for a solution to let only one instance can be run at a time on a system and if the user clicks again while the application is running nothing happens. I think it's called singleton but don't know how to implement it.
You could try JUnique. It's an open source library doing exactly what you ask for. Import junique-1.0.4.jar to your project as a library. It's just 10kb file.
It's manual neatly describes how to implement it on a project. For a JavaFX application, implementation would look something like this:
Make sure to import these classes to your main
import it.sauronsoftware.junique.AlreadyLockedException;
import it.sauronsoftware.junique.JUnique;
public static void main(String[] args) {
String appId = "myapplicationid";
boolean alreadyRunning;
try {
JUnique.acquireLock(appId);
alreadyRunning = false;
} catch (AlreadyLockedException e) {
alreadyRunning = true;
}
if (!alreadyRunning) {
launch(args); // <-- This the your default JavaFX start sequence
}else{ //This else is optional. Just to free up memory if you're calling the program from a terminal.
System.exit(1);
}
}
One easy solution that I've used is, when you start the application, it creates a file (I named it .lock but you can call it whatever you want), unless the file already exists, in which case the application terminates its execution instead of creating the file.
You will need to bind your application with a resource. It can be a file, port etc.
You can change the code on startup to check if the file is locked. The below code will give you some idea
FileOutputStream foStream = new FileOutputStream("/tmp/testfile.txt");
FileChannel channel = fileOutputStream.getChannel();
FileLock lock = channel.lock();
If you'd properly package your JavaFX code as a real application instead of just throwing it into a jar, you might get that functionality for free and without all these hacks. If I package my JavaFX code on my Mac with the jpackage tool, the result will be a full featured macOS application. That means that when I double-click its icon somewhere several times, only one instance of the application will be started. This is the default behaviour on Macs and properly packaged JavaFX applications just stick to that rule too. I can't say however what the behaviour on Windows or Linux is because I currently don't have such a box running. Maybe someone who knows can add this as a comment.
Related
I am using Java and selenium to write some tests. I need to have my screen records while the tests are running it makes much easier for me to track if any bugs occurs. The problem is that I need to run more than one tests at the same time and as I have only one monitor I cannot record all of their screen records at the same time so I have to run the test one after each other. I was wondering if there is any way that I can run all my tests and actually minimize their browsers windows but still record what is going on at each minimized chrome window. My question may sound a bit very strange but that makes my testing very faster.
Yes, definitely we can take multiple screenshots. There is no affect whether the browser is in minimize or Maximize condition. Just you have to switch the new opened window & add "Take screenshot" method after each method where you have to take screenshot.
Take screenshot method can work in both mode while browser is either in Minimize or Maximize condition.
For screenshot you can may use the below code:
public void getscreenshot() throws Exception
{
File scrFile = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);
//The below method will save the screen shot in d drive with name "screenshot.png"
FileUtils.copyFile(scrFile, new File("D:\\screenshot.png"));
}
or you can opt for the multi-screen capture and the code for that is below :
public void GoogleAbout() throws Exception {
driver.get(baseUrl); // Enter the URL as per your choice
driver.findElement(By.linkText(Prop.getProperty("AboutLinkText"))).click(); //find the web element
MultiScreenShot multiScreens = new MultiScreenShot("C:\\New\\","GoogleAbout"); // Here we need to create the object which will take two arguement one is the path to save the file and second one is class name
multiScreens.multiScreenShot(driver);
driver.findElement(By.linkText("More about our philosophy")).click();
multiScreens.multiScreenShot(driver);
}
To enable the multi-screenshot you have to download the JAR file and then attached it to your project and then :
import multiScreenShot.MultiScreenShot;
I am making a program for computer surveillance at the moment.
It's for a competition in my country Croatia(InfoKup).
I have several options for sending command to another PC, but I
want to make the possibility for the command extension for people
who know Java. So I want to make the user be able to add some of his
custom commands for the program. For example something like
Minecraft mods. I know it is possible, but how would I go about
doing that.
Any help would be greatly appreciated. My code on GitHub:GitHub
Don't mind the stream thing.
It's something my friend is experimenting with.
EDIT: e.g.
Currently I have the possibility to send popups to another PC. What if the extension maker knew the code to send cmd commands and wants to add that function. He makes an extension and puts it in the extension folder. Voila we have a new possibility.
EDIT 2:
Don't be so harsh on me pls :). Thx for the dynamic class loading tip. I have been looking into that, and it looks promising.
Basically what I want to have possible is the user to drop the "mod/extension/whatever" in the "mod/extension/whatever" folder, and the program would load it and put all of the buttons declared in the class in to the GUI, and with them the function. I think I'm getting the hang of this, but any tips would be helpful.
e.g.
package sth.sth;
import blah.blah.*;
public class ClassSTH extends SchoolarButton{
public ClassSTH(String params){
super(params);
}
#Override
public void OnClick(){
doStuff();
}
}
EDIT:
The problem is easily solvable using Java Reflection! I wish someone posted that as an answer befpre blatanty downvoting a question because pf a GitHub link that was there to prpve that I've actually done something.
This kind of thing can be accomplished by using Java Reflection!
How to load and invoke a method on an external jar:
File f = new File("plugin.jar");
URLClassLoader cl = new URLClassLoader(new URL[]{f.toURI().toURL(), null});
Class<?> clazz = cl.loadClass("epicurus.Client");
Method main = clazz.getMethod("main", String[].class);
main.invoke(null, new Object[]{new String[]{}});
I have an application built on top of NetBeans. We have some long running jobs that I'd like to keep running in the background, but allow the user to see progress on the bar on the lower right.
E.G:
I can't seem to access it from my code.
Initially I didn't have this library
org.netbeans.api.progress.ProgressHandle;
org.netbeans.api.progress.ProgressHandleFactory;
I had to go out and hunt down the JAR file. That doesn't make whole lot of sense to me, I figure it should be available.
This creates an error when I try to call the ProgressHandle into effect, I get this error
java.lang.ClassNotFoundException: org.openide.awt.StatusLineElementProvider …
Followed by a stack trace. Obviously I don't have all the packages necessary to operate this.
What the big question is then, what am I missing as far as accessing these NetBeans libraries correctly?
Thanks,
Here's the code when I'm trying to call the progressbar into action
`
ProgressHandle progr;
if (thread == null) {
thread = new Thread() {
#Override
public void run() {
progr.start();
progr.progress("Sending backup to remote server.");
… //Some code that sends a backup
progr.finish();
`
I'll be rewriting this question a few times, until I think it's clear, I'm open to input
Add a module dependency on Progress API. Right click on your module > properties.Select Libraries from the left panel. Click Add to open up the module dependency dialog. Select Progress API and click OK. Now you have the dependency on Progress API and you can use it as
ProgressHandle ph = ProgressHandleFactory.createSystemHandle("My Task");
ph.start(100);
Edit:
Also u dont have to add any jar files.. The Progress API module dependency will take care of that
When my Java-based application (not a browser-based applet) copies plain text to the system clipboard on Linux, many programs are not able to access the clipboard data, but some are.
Here's the simplest test I could make:
import java.awt.datatransfer.*;
import java.awt.Toolkit;
import java.io.*;
public final class PasteTest {
public static void main (String... args) {
String mytext = "This is a test message, testing, 1, 2, 3....";
StringSelection sel = new StringSelection(mytext);
Clipboard clip = Toolkit.getDefaultToolkit().getSystemClipboard();
clip.setContents(sel, null);
try {
Thread.sleep(1000);
} catch (Exception e) {
}
}
}
While this program is running, File > Paste in OpenOffice (LibreOffice 3.5.7.2) is able to access the text it placed on the system clipboard. But using File > Paste in Gnome Terminal, Mozilla Thunderbird & Firefox, and many other programs can not. The Paste option is gray, as if the clipboard is empty.
How can I make my Java program publish plain text to the system clipboard on Linux (testing on Ubuntu 12.04) so all programs can access it?
Your code is fine. Its problem is that it terminates too soon.
Under X window system, the process that puts something on 'clipboard' (that is, the selection named 'clipboard') must stay alive for the copied data to survive. (Read about active and passive buffers, and notice that selections are of the active kind).
While your process runs, that is, sleep()s, you can paste the data anywhere. Once it terminates, clipboard goes empty.
This is not special behavior of Java; you can easily reproduce it with charmap or any other program you don't mind closing.
I don't know how LibreOffice scored a point in your test. Possibly it was first on your alt+tab list. In my tests, LibreOffice behaved like any other app: 'paste' worked as long as the Java process was alive, and stopped working as the process terminated.
I don't know how to fix it in general case. Running a clipboard manager (that remembers multiple copied items and thus probably owns all of them) might help.
From within Java, I am opening an Excel file with the default file handler (MS Excel, in this case :-) ) using the method described in this stackoverflow question:
Desktop dt = Desktop.getDesktop();
dt.open(new File(filename));
However, the Excel program doesn't get the focus. Is there any easy way to do so?
Edit: There is a related stackoverflow question for C#, but I didn't find any similar Java method.
Edit 2: I've did some simple tests, and discovered that Excel starts and gets the focus whenever no instance of Excel is running. When Excel is already open en NOT minimized, the application doesn't get the focus. If instead the Excel Windows was minimized, the above code will trigger a maximization of the window and Excel getting the focus (or vice versa :-) ).
If you only care about Windows (implied in the question), you can change the way you invoke Excel: use "cmd start...".
I have been using this piece of code to launch Windows applications for some time now. Works every time. It relies on the file association in Windows to find the application. The launched application becomes the focused window on the desktop.
In your case, Excel should be associated with .xls, .csv and other typical extensions. If it is, Windows will launch Excel, passing your file to it.
Usage:
MyUtilClass.startApplication( "c:\\mydir\\myfile.csv", "my window title" );
file is the full path to the input file for Excel and title is the window title (the application may or may not take it - Excel changes the window title).
public static void startApplication( String file, String title )
{
try
{
Runtime.getRuntime().exec( new String[] { "cmd", "/c", "start", title, file } );
}
catch( Exception e )
{
System.out.println( e.getMessage() );
}
}
From a scala-program, which runs in the JVM too, I can open an application, and that get's the focus by default. (Tested with xUbuntu, which is a kind of Linux).
import java.awt.Desktop
val dt = Desktop.getDesktop ();
dt.open (new java.io.File ("euler166.svg"));
I can't say, whether this is specific for Linux, or maybe something else - however starting Inkscape in my example, excel in yours, may take a few seconds, while the user impatiently clicks in the javaprogram again, thereby claiming the cursor back. Did you check for that?
You could then change to the last application, at least on Linux and Windows with ALT-Tab aka Meta-Tab (again shown in scala code, which you can easily transform to javacode, I'm sure):
import java.awt.Robot
import java.awt.event._
val rob = new Robot ()
rob.keyPress (KeyEvent.VK_META)
rob.keyPress (KeyEvent.VK_TAB)
rob.keyRelease (KeyEvent.VK_TAB)
rob.keyRelease (KeyEvent.VK_META)
but unfortunately the unknown source off more trouble, also known as user, might do nothing, so switching would be the false thing to do. Maybe with a thread, which checks for a certain amount of time, whether the java-program has the focus, but it keeps a form of roulette, in an interactional environment, because the user may have a fast or slow machine, or change to a third application meanwhile, and so on. Maybe a hint before triggering the new app is the best you can do?