I've come again in one of THOSE situations where it is just impossible to stop/destroy/suspend a thread. .interrupt() doesn't do the trick and .stop() and .suspend() are deprecated.
Very simple example:
public class TimerThread extends Thread {
private JPanel colorPanel;
public TimerThread(JPanel colorPanel) {
this.colorPanel = colorPanel;
}
public void run() {
while (true) {
try {
Thread.sleep(1000);
colorPanel.repaint();
} catch (Exception ex) {
//do Nothing
}
}
}
}
What this does is repaint a certain JPanel every second to change its colour. I want to start and stop the thread like this from another class:
timer = new Thread(new TimerThread(colorPanel));
startButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.start();
}
});
stopButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.interrupt();
}
});
Obviously (?) this doesn't work... I know I could use a Timer, a SwingWorker or declare the timer as timer = new TimerThread(colorPanel); and use a boolean instead of "true" in the run method, but I've been asked to declare timer as a "Thread" and nothing else.
To my surprise (or is this that stupid?), even this didn't work:
startButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer = new Thread(new TimerThread(colorPanel));
timer.start();
}
});
stopButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.interrupt();
timer = null;
}
});
So my question is simple: How do you make threads Start/Pause/Resume/Stop in Java?
when you get an interrupt you should start the cleanup and return a.s.a.p. (or at the very least reset the interrupted status)
while (true) {
try {
Thread.sleep(1000);
colorPanel.repaint();
} catch(InterruptedException e){//from sleep
return;//i.e. stop
} catch (Exception ex) {
//do Nothing
}
}
another way is to check Thread.interrupted() in the condition (but you'll need to reset the interrupted status in the catch of InterruptedException
however in swing you can use javax.swing.Timer to let an event run every so often and stop that with the api of that
javax.swing.Timer timer = new Timer(1000,new ActionListener() {
public void actionPerformed(ActionEvent e) {
colorPanel.repaint();
}
});
timer.setRepeats(true);
startButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.start();
}
});
stopButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.stop();
}
});
Try this:
public class TimerThread extends Thread {
private volatile boolean stop = false;
private JPanel colorPanel;
public TimerThread(JPanel colorPanel) {
this.colorPanel = colorPanel;
}
public void stopTimer() {
stop = true;
}
public void run() {
while (stop == false) {
try {
Thread.sleep(1000);
colorPanel.repaint();
} catch (Exception ex) {
//do Nothing
}
}
}
}
// Why new Thread(new TimerThread(...))?
// timer = new Thread(new TimerThread(colorPanel));
timer = new TimerThread(colorPanel)
startButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.start();
}
});
stopButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.stopTimer();
}
});
Also have a look at here to see how you can replicate stop now that it's deprecated.
You make them co-operate, basically. You have some shared flags to let them see what they should be doing, and whenever you would sleep, instead you wait on some shared monitor. Then when you want to control the thread, you set the appropriate flag and notify the monitor so that if the thread was waiting, it will wake up and notice that it should suspend/stop/whatever. Obviously you need to take the normal sort of care around shared state, using volatile variables, Atomic* objects or locking to make sure that every thread sees the updates made by every other thread.
Anything non-cooperative is risky due to the chance of corrupting state half way through an operation.
It is dangerous to stop threads pre-emptively. Doing so leads to deadlocks, resource leaks and so on. Instead you should use a cooperative signaling mechanism.
Signal to the thread that you want it to stop, and then wait for it to do so. The thread should regularly check whether it needs to stop and react accordingly.
Instead of looping while (true), you should loop while the thread is not interrupted:
#Override public void void() {
// some kind of initialization...
while (!Thread.currentThread().isInterrupted()) {
try { ...
} catch (InterruptedException e) {
Thread.currentThread().interrupt(); // ensure interrupt flag is set
}
}
// some kind of cleanup
}
If InterruptedException is not thrown by anything inside your while block, either you don't use blocking operations (and simply calling Thread.interrupt() on this thread would stop it the next iteration) or you use some blocking calls that are not well behaved (there are many such examples in the JCL itself!).
The correct way to do this is indeed to have a variable that determines when the Thread should be stopped, exiting from its run method. You can find more information about how to do this properly here
With this solution you won't get "instantaneous" updates that you could get with wait/notify or interrupt, but if you don't mind the fraction of a second delay, it should do the job.
volatile boolean stopped = false;
volatile boolean paused = false;
pauseButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
paused = true;
}
});
resumeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
paused = false;
}
});
stopButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
stopped = true;
}
});
... TimerThread
public void run() {
while (stopped == false) {
try {
Thread.sleep(1000);
if (stopped)
break;
if (!paused)
colorPanel.repaint();
} catch (Exception ex) {
//do Nothing
}
}
}
Related
I want to make an easy app. But I want to stop thread with a button. This code doesn't work. I saw all web sites like this way. I don't understand why not working.
Thread is starting with a btnStart.
btnStop isn't working. I wrote stopThread() function for stopping.
Which how this can do another way? Any idea?
private volatile boolean isRunning;
==============
private void stopThread() {
isRunning=false;
Thread.currentThread().interrupt();
}
==============
private final void runThread() {
new Thread() {
public void run() {
while (isRunning) {
try {
Random r = new Random();
islemler[0] = "+";
islemler[1] = "-";
islemler[2] = "*";
islemler[3] = "/";
for (int i = 0; i <10; i++) {
islem1 = islemler[r.nextInt(4)];
islem2 = islemler[r.nextInt(4)];
islem3 = islemler[r.nextInt(4)];
islem4 = islemler[r.nextInt(4)];
txt1.setText("1"+islem1+"1");
txt2.setText("1"+islem2+"1");
txt3.setText("1"+islem3+"1");
txt4.setText("1"+islem4+"1");
Thread.sleep(150);
Thread.sleep(50);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}.start();
}
==============
btnStart.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
isRunning=true;
runThread();
**This part is working**
}
});
==============
btnStop = new JButton("Stop");
btnStop.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
stopThread();
**But this part is not working. Can you help??**
}
});
The Problem
You have two threads open, possibly three if you have one set aside for the ui.
The first thread is the one the program launches on, and the second would be where you creating the random object and for-loop. When you are calling "stop thread" you are doing so from either the main thread or the third thread for the ui.
This means that
Thread.currentThread().interrupt();
is not closing the correct thread.
The Solution
For a solution to this problem, look at this GeeksForGeeks article which suggests storing threads as a variable and then you can reliably call the interrupt method on it.
This application has 2 threads the one shown here calls a method that pauses an auto clicker method every 4 seconds(just for ease) to do some mouse movement. I want it to stop the timer when you click the gui stop button.
Right now when you hit stop and then start again it then has two timers that will execute the code; and so on.
Action Listener Stuff.
class MyButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(view.getBtnStart()))
{
autoClick.unTerminate();
bool = true;
getInfo();
}
if (e.getSource().equals(view.getBtnExit()))
{
System.exit(0);
}
if (e.getSource().equals(view.getBtnStop()))
{
bool = false;
autoClick.terminate();
}
}//end of actionPerformed
}//end of inner class
Thread
Thread t2 = new Thread(new Runnable() {
#Override
public void run() {
Timer timer = new Timer(4000, new ActionListener() {//301000 5minutes and 1second
#Override
public void actionPerformed(ActionEvent evt) {
autoClick.timeOverload();
}
});
//if (!bool){timer.stop();}
timer.setRepeats(true); //false only repeates once
timer.start();
}
});//end of t2
It calls the timeOverload method repeatedly.
Thanks for your time and helping a newbie out :).
Here is a quick sample of how to declare a instance outside of your thread and be able to control it outside of it.
public static void main(String[] args){
final Timer timer = new Timer(500, new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("tick");
}
});
timer.setRepeats(true);
Thread t = new Thread(new Runnable() {
public void run() {
timer.start();
}
});
t.start();
try {
Thread.sleep(2600);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
timer.stop();
}
Basicly, you need to set the instance final to be used in a anonymous class (the ActionListener implementation).
Here, I just start the thread then pause the process for a few seconds and stop the timer.
Note that here, the Thread don't do anything else so it ends directly. You will need to tweek this a bit to match your needs but you have a working example.
EDIT : (DevilsHnd, if you post your answer, notify me, I will remove this part)
Using a flag (here in a Class)
public class Main {
public static void main(String[] args){
new Main();
}
boolean running = true;
public Main(){
final Timer timer = new Timer(500, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(!running){
((Timer)e.getSource()).stop();
} else {
System.out.println("tick");
}
}
});
timer.setRepeats(true);
timer.start();
try {
Thread.sleep(2600);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
stop();
}
public void stop(){
running = false;
}
}
Calling the Main.stop() will set the flag to false, on each action performed, you check this flag, if it is false, you get the timer from the event (in the source) and stop it.
String move=jTextField1.getText();
i=Integer.parseInt(move);
timer = new Timer(1000,new ActionListener(){
public void actionPerformed(ActionEvent e)
{
i--;
if(i<=0)
{
if(move.equals("0"))
{
Thread th=new Thread(new DetectImage());
th.start();
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
new TrafficMainGUI(storeValue);
}
});
}
timer.stop();
}
}
jTextField1.setText(""+i);
}
});
timer.start();
move=""+i;
//Thread th in DetectImage class
public void run()
{
while(stay<20)
{
try {
stay++;
//few contions
Thread.sleep(1000);
}
}
}
//EveryThing is working fine with thread but when i use SwingUtiities.invokeLater()
to call the same class in which this code is there for getting infinite condition.
This doesnot redirect it to the class TrafficMainGUI.Is there some other method to achieve this kind of model.
jTextField1.setText(""+i); must be wrapped in invokeLater for this job by invoked from util.Timer
use Swing Timer instead
if(move.equals("0")) { is about animations, then to use Swing Timer exclusivelly
In my GUI I have a PDF file creation operation. The operation can take up to 10-15 seconds to complete. When I start the operation, I attach a listener to it. The listener changes the cursor and disables the GUI, until the operation completes.
I would also like to add a progressbar, so the users will have a idea when it is going to complete.
Created a method startProgressBar() and called it from the start of the operation method.
See Below:
private void startSavePdfOperation() {
startProgressBar();
saveOp = new AplotSaveOperation(appReg.getString("aplot.message.SAVETOPDF"), "PDF", session);
saveOp.addOperationListener(new MyOperationListener(this) {
startProgressBar Method - See Below:
public void startProgressBar() {
Shell shell = new Shell(getShell());
shell.setSize(260, 120);
final ProgressBar bar = new ProgressBar(shell, SWT.SMOOTH);
bar.setBounds (20, 20, 200, 20);
shell.open();
final int maximum = bar.getMaximum();
new Thread(new Runnable() {
public void run() {
for (final int[] i = new int[1]; i[0] <= maximum; i[0]++) {
try {Thread.sleep (100);} catch (Throwable th) {}
if (Display.getDefault().isDisposed()) return;
Display.getDefault().asyncExec(new Runnable() {
public void run() {
if (bar.isDisposed ()) return;
bar.setSelection(i[0]);
}
});
}
}
}).start();
The code above created the ProgressBar. The issue is that the operation would end well before the progressbar indicator was close to ending.
Question: Is this because in the method I am creating a new thread and the indicator is updating according to the new thread and not the operation thread?
Question: Is it possible to create a new thread that watches the GUI thread and updates the progressbar accordingly?
Read a article suggesting using ProgressMonitorDialog with IRunnableWithProgress.
Method startProgressBar using ProgressMonitorDialog - see below:
public void startProgressBar() {
ProgressMonitorDialog dialog = new ProgressMonitorDialog(getShell());
try {
dialog.run(true, true, new IRunnableWithProgress(){
public void run(IProgressMonitor monitor) {
monitor.beginTask("Some nice progress message here ...", 100);
** getThread(); **
monitor.done();
}
});
}
catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void getThread() {
new Thread etc.. etc...
}
It seems that it will have the same issues with threading and updating as the code above.
Question: So now I am thinking can I just add or update the ProgressBar to my existing Listener
OperationListener Code - see below:
public abstract class MyOperationListener implements InterfaceAIFOperationListener {
AplotCreatePDFDialog w = null;
public MyOperationListener(AplotCreatePDFDialog win) {
w = win;
}
public void startOperation(String startMessage) {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_WAIT));
w.recursiveSetEnabled(getShell(), getShell().getEnabled());
w.getShell().setEnabled(!getShell().getEnabled());
}
});
}
public void endOperation() {
try {
endOperationImpl();
}
finally {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_ARROW));
w.recursiveSetEnabled(getShell(), true);
w.getShell().setEnabled(!getShell().getEnabled());
w.close();
}
});
}
}
abstract protected void endOperationImpl();
} // end class MyOperationListener
Thanks for any help you can give me with this.
EDIT
Baz, your answer below is exactly what the question asked, so thank you for answering.
But I am starting to think that what I am trying to do is not possible.
When my operation starts, I wanted the progress bar indicator to start and when my operation ended I wanted the indicator be at the end and the monitor would close.
I thought there might bee a way to use my listener to add the progressbar. Something like the following.
public void startOperation(String startMessage) {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
->monitor.beginTask("Creating PDF File(s)", IProgressMonitor.UNKNOWN);<-
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_WAIT));
w.recursiveSetEnabled(getShell(), getShell().getEnabled());
w.getShell().setEnabled(!getShell().getEnabled());
}
});
}
public void endOperation() {
try {
->monitor.worked(1);<-
endOperationImpl();
}
finally {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_ARROW));
w.recursiveSetEnabled(getShell(), true);
w.getShell().setEnabled(!getShell().getEnabled());
->monitor.done();<-
w.close();
}
});
}
}
abstract protected void endOperationImpl();
} // end class MyOperationListener
But I am starting to see that the ProgressBar has to have some sort of measurement to display the indicator correctly.
I would be happy if the indicator just went back and forth and the monitor would close at the end of the operation.
Why not use ProgressMonitorDialog?
Here is a related answer from me showing a simple example.
This is what it looks like:
If you are not sure about the workload, use this code:
monitor.beginTask("Copying files", IProgressMonitor.UNKNOWN);
It will show the idle bar while running.
Thread thread;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_yippi);
final Handler hn=new Handler();
final TextView text=(TextView)findViewById(R.id.TextView01);
final Runnable r = new Runnable()
{
public void run()
{
text.settext("hi");
}
};
thread = new Thread()
{
#Override
public void run() {
try {
while(true) {
sleep(1750);
hn.post(r);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
thread.start();
thread.stop();}
The code here. I can not stop the runnable thread. Also, thread.stop() and thread.destroy() are deprecated. Can somebody help me? And also I don't understand how to stop the thread with the thread.interrupt() method. What's wrong?
The JavaDoc for Thread.stop() lists the following article as explanation for why stop() is deprecated: http://docs.oracle.com/javase/6/docs/technotes/guides/concurrency/threadPrimitiveDeprecation.html
Most uses of stop should be replaced by code that simply modifies some variable to indicate that the target thread should stop running. The target thread should check this variable regularly, and return from its run method in an orderly fashion if the variable indicates that it is to stop running. To ensure prompt communication of the stop-request, the variable must be volatile (or access to the variable must be synchronized).
interrupt() is more suitable to stop some Thread from waiting for something, that is probably not coming anymore. If you want to end the thread, it's best to let its run() method return.
Create a boolean variable to stop the thread and use it in while(boolean) instead of while(true).
You can use Thread.interrupt() to trigger the InterruptedException within your thread. I've added code below that demonstrates the behavior. The mainThread is where your code would be and the timer Thread is just used to demonstrate delayed triggering of the interrupt.
public class Test {
public static void main(String[] args) {
final Thread mainThread = new Thread() {
#Override
public void run() {
boolean continueExecution = true;
while (continueExecution) {
try {
sleep(100);
System.out.println("Executing");
} catch (InterruptedException e) {
continueExecution = false;
}
}
}
};
mainThread.start();
Thread timer = new Thread() {
#Override
public void run() {
try {
sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Stopping recurring execution");
mainThread.interrupt();
}
};
timer.start();
}
}
You can use interrupt method of Thread to try stop a thread, like below code.
May be it`s useful to you.
public class InterruptThread {
public static void main(String args[]){
Thread thread = new Thread()
{
#Override
public void run() {
try {
while(true) {
System.out.println("Thread is Runing......");
sleep(1000);
}
} catch (InterruptedException e) {
// restore interrupted status
System.out.println("Thread is interrupting");
Thread.currentThread().interrupt();
}
}
};
thread.start();
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Will Interrupt thread");
thread.interrupt();
}
}