I am unclear on how to use wait() and notify() to pause a thread. I read talk about synchronizing, but I'm unsure how to do it in my instance. I have a music player with a progress bar where I want to pause the thread in control of syncing the progress bar with the music. Here is the thread I want to pause:
#FXML private void clickedButton(ActionEvent event){
shuffle.setOnAction(e -> {
artistPane.setText(model.getCurrentSong());
if(firstTime){
//Multithreading with JavaFX. Essentially this other thread will check the slider to make sure its on track.
sliderThread = new Task<Void>() {
#Override
protected Void call() throws Exception {
boolean fxApplicationThread = Platform.isFxApplicationThread();
System.out.println("Is call on FXApplicationThread: " + fxApplicationThread);
//this is an infinite loop because now I only need to make this thread once, pausing and starting it, as opposed to making many threads
for(;;){
Thread.sleep(100);
progressBar.setValue(controller.getPercentageDone());
}
}
};
new Thread(sliderThread).start();
firstTime = false;
}else if(!model.getIsPlaying()){
//I want to start the thread here
}
controller.shuffle(); //this will start the music on the next song
});
Here is the second half where I also want to pause and start the thread:
play.setOnAction(e -> {
controller.play(); //this will pause/start the music
if(!model.getIsPlaying()){
//where I want to pause the thread.
}else{
//I want to start the thread here
}
});
I will try to give you simple example and you try to apply it to your program...
public class TestClass extends JPanel {
/**
*
*/
private static final long serialVersionUID = 1L;
private Thread playThread ;
TestClass() {
playThread = new Thread(new Runnable() {
#Override
public void run() {
System.out.println("DO SOME THING HERE");
System.out.println("SONG WILL PLAY.....");
}
});
}
public void startMyPlayer() {
System.out.println("PLAYING NOW...");
playThread.start();
}
public void pauseMyPlayer() throws InterruptedException {
System.out.println("PAUSED NOW...");
playThread.wait();
}
public void resumeMyPlayer() {
System.out.println("RESUMING NOW...");
playThread.notify();
}
}
That's it.I hope this help you.
Related
I have a simple class which has a thread in it. Whenever user clicks on a button, I want to run the thread. Everything works great, except that whenever I click on the button while the thread is already running, my onTouch executes only after the thread has finished executing.
..
MyTouchAnimatorClass touchAnimatorClass = new MyTouchAnimatorClass();
view.setOnClickListener( new View.OnClickListener()
{
#Override
public void onClick( View view )
{
touchAnimatorClass.onTouch();
}
});
..
And my class with the thread:
Class MyTouchAnimatorClass
{
private boolean threadRunning = false;
public void onTouch() // <-- only executes AFTER the thread is complete
{
if( !threadRunning )
animate();
}
private void animate()
{
threadRunning = true;
Runnable r = new Runnable()
{
#Override
public void run()
{
activity.runOnUiThread(new Runnable()
{
#Override
public void run()
{
int i=0;
boolean doBreak = false;
while( true )
{
i+=1;
if( i == 100 )
break;
}
}
}
}
}
new Thread( r ).start();
threadRunning = false;
}
}
I can't understand why this is happening, isn't the Runnable running in its own thread? Any suggestions please? Thank you!
EDIT:
I tried using
new Thread( r ).start();
Instead of:
r.run();
But unfortunately the same problem persists:
If I click the button the second time (while the thread is still running from the first click), it should execute onTouch, but shouldn't execute animate() since it is still running from the previous click.
What actually happens: The touch is non response until the thread from the first click has finished executing. Then onTouch triggers (even though I pressed it few seconds ago) and a new thread is started again.
If I press the button 10 times quickly, it will do 10 loops in a row, instead of doing one and blocking the others.
activity.runOnUiThread is asking the Android system to run this Runnable on the UI thread.
You can rather do new Thread(r).start();
Like this:
private void animate()
{
threadRunning = true;
//Define the work as a Runnable
Runnable r = new Runnable()
{
#Override
public void run()
{
int i=0;
//boolean doBreak = false; //Not used
while( true )
{
i+=1;
if( i == 100 )
break;
}
threadRunning = false; //Just before leaving
}
}
//Give that work to a new thread and start the thread
new Thread(r).run();
}
Runnable isn't a thread, is just a set of instructions to be executed in a thread
in order to achieve what you want you need to do
new Thread(r).start(); at end of your code
I'm new in java. I'm trying to understand thraeads and timers in java. It was big problem for me to undate ProgressBar from another thread. I read many posts and found answers. So can you say is this the best way to resolw my task. So, what I want is to run second thread and when it's done, stop progress bar and change text on the button. So I creat Frame with button and progress bar in Test class:
After I realize action listener for Button to run second thread:
public class Test extends javax.swing.JFrame {
RunBg thread = new RunBg();
....
// declaration for button, progressbar and main() method
....
private void jButton1MouseClicked(java.awt.event.MouseEvent evt) {
// needed to check is the thread running at first time else creat new object and rund hread again cause thread can be executed once
if(thread == null){
thread = new RunBg();
}
if (jProgressBar1.isIndeterminate()) {
jProgressBar1.setIndeterminate(false);
jButton1.setText("Run!");
thread.suspend();
} else {
jButton1.setText("Working...");
jProgressBar1.setIndeterminate(true);
// let us know is the second thread running or nope so we can know resume it or pause
if (thread.isAlive()) {
thread.resume();
} else {
thread.start();
}
timer.start();
}
}
/*
Then I creat timer to know is my thread still alive else change Progress bar and button
*/
Timer timer = new Timer(100, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(!thread.isAlive()){
thread.stop();
jProgressBar1.setIndeterminate(false);
jButton1.setText("Запустить!");
timer.stop();
// thread.interrupt();
thread = null;
}
}
});
...
// end of class
}
And my second class for another thread named RunBG:
public class RunBg extends Thread{
int i = 0;
public void run(){
while(i<20000){
System.out.println(">>>"+i);
i++;
}
System.out.println("<<<Finished>>>");
}
}
Everythig works fine , but I have question. Is there a better way to realize my task or maybe I made some mistakes. Also I thik that my code will help another beginners who looking for help to understand how it's work.
public void myMethod()
{
if (capture.isOpened()) {
while (true) { //This is The main issue.
capture.read(webcam_image);
if (!webcam_image.empty()) {
webcam_image = my_panel.detect(webcam_image);
temp = my_panel.matToBufferedImage(webcam_image);
my_panel.setimage(temp);
my_panel.repaint();
System.out.print("."); // It should prints "." but the above code doesn't works.
} else {
System.out.println(" --(!) No captured frame -- Break!");
break;
}
}
}
}
This is invoking code of the above method...
actually it's an ActionEvent which can be fire on menu is clicked.
if (e.getActionCommand().equals("goLive")) {
System.out.println("Live...");
myMethod();
}
I know actually it's problem of the infinite while loop but here I need to put this condition at any cost.
The exact solution for this type of problem is Timer class. We can overcome this issue using the following code.
Timer timer = new Timer();
timer.schedule(new TimerTask() {
#Override
public void run() {
myMethod();
}
}, 0);
Thanks google, oracle and java doc
Assuming that myMethod is called by an event listener (actionPerformed), the infinite loop is blocking the event dispatch thread.
You can avoid this by using SwingWorker or executing your loop on another thread:
public void myMethod()
{
if (capture.isOpened()) {
new Thread(new Runnable() { //Create a new thread and pass a Runnable with your while loop to it
#Override public void run() {
while (true) {
capture.read(webcam_image);
if (!webcam_image.empty()) {
webcam_image = my_panel.detect(webcam_image);
temp = my_panel.matToBufferedImage(webcam_image);
SwingUtilities.invokeLater(new Runnable() { //The following lines affect the GUI and must be executed on the event dispatch thread, so they should be wrapped inside a Runnable
#Override public void run() {
my_panel.setimage(temp);
my_panel.repaint();
}
}
try{
Thread.sleep(xxx); //consider waiting for a moment (e.g. 16ms)
} catch(InterruptedException e) { ... }
System.out.print(".");
} else {
System.out.println(" --(!) No captured frame -- Break!");
break;
}
}
}
}).start(); //Let the thread loop in the background
}
}
I use Swing Application Framework in my program. And I have some long-time work. I use org.jdesktop.application.Task for it. Another programmer wrote two Tasks before I took this project (I can not ask him about the programm). When Tasks are executing user sees progress bar without showing percent complete, but what shows "Wait" message and user can not click to a main window while Task does not ended. It is fine! But I could not find place where ProgressBars was created. May be it is described in some xml-file or property-file?
Also I wrote another Tasks and when they run, progress bar which I created is not displayed or displayed incorrectly. I read about ProgressBar and ProgressMonitor, but it does not help me.
Programm continue to run after someTask.execute(), but I want to it displays ProgressBar, ProgressMonitor or something else and user can not click the main window and window will display correctly. Now window has black "blocks" when user change it.
May be I need use org.jdesktop.application.TaskMonitor. I try to use it as here https://kenai.com/projects/bsaf/sources/main/content/other/bsaf_nb/src/examples/StatusBar.java?rev=235 , but my main window is displayed incorrectly and my ProgressBar is not displayed.
I need to when Task is running program waits it, but user can see ProgressBar, can cancel the operation and can not click to the main window. How can I do it?
Here my code:
public class A{
#Action(name = "ActionName", block = Task.BlockingScope.APPLICATION)
public RequestInfoTask requestInfo() {
RequestInfoTask task = new RequestInfoTask(Application.getInstance());
isSuccessedGetInfo=false;
task.addTaskListener(new TaskListener.Adapter<List<InfoDTO>, Void>() {
#Override
public void succeeded(TaskEvent<List<InfoDTO>> listTaskEvent) {
isSuccessedGetResources=true;
}
});
//Here I want to the program shows ProgressMonitor and user can not click to the main window.
//But small window with message "Progress..." is displayed for several seconds and disappear.
ProgressMonitor monitor = new ProgressMonitor(getMainView(), "Wait! Wait!", "I am working!", 0, 100);
int progress = 0;
monitor.setProgress(progress);
while(!task.isDone()){
monitor.setProgress(progress+=5);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
}
monitor.setProgress(100);
//This code must run after "task" finishes.
if(isSuccessedGetInfo){
MyTask2 task2 = new MyTask2(Application.getInstance());
isSuccessedTask2=false;
task2.addTaskListener(new TaskListener.Adapter<Map<?,?>, Void>(){
#Override
public void succeeded(TaskEvent<Map<String, ICredential>> arg0) {
isSuccessedTask2=true;
}
});
//Do something with results of task2.
}
return task;
}
}
public class RequestInfoTask extends Task<List<InfoDTO>, Void> {
public RequestInfoTask(Application application) {
super(application);
}
#Override
protected List<InfoDTO> doInBackground() throws Exception {
List<InfoDTO> result = someLongerLastingMethod();
return result;
}
}
Part of your problem sounds like it comes from not using the EDT correctly. Any long running task needs to be started in it's own thread to keep the GUI responsive and repainting.
Ideally you'd be following a MVC pattern. In that case you place your Progress Bar in the view, your flag (that indicates whether the task should be running still) in the control, and your long running task in in the Model.
From that point, if your model checks periodically if it should stop (Probably at good stopping points), you can reset everything.
Here's an example with MVC:
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;
public class ProgressBarDemo{
public static class View extends JPanel{
Controller control;
public JProgressBar progressBar = new JProgressBar(0, 100);
JButton button = new JButton("Start Long Running Task");
public View(Controller controlIn){
super();
this.control = controlIn;
setLayout(new BorderLayout());
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
//Toggle between running or not
if(control.isRunning){
control.isRunning = false;
button.setText("Canceling...");
button.setEnabled(false);
} else{
control.isRunning = true;
button.setText("Cancel Long Running Task");
control.startTask();
}
}});
progressBar.setStringPainted(true);
add(progressBar);
add(button, BorderLayout.SOUTH);
}
}
//Communications gateway
public static class Controller{
View view = new View(this);
boolean isRunning = false;
public void updateProgress(final int progress){
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
view.progressBar.setValue(progress);
}});
}
public void reset(){
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
isRunning = false;
view.button.setText("Start Long Running Task");
view.progressBar.setValue(0);
view.button.setEnabled(true);
}});
}
public void startTask(){
LongRunningClass task = new LongRunningClass(this);
new Thread(task).start();
}
}
public static class LongRunningClass implements Runnable{
Controller control;
public LongRunningClass(Controller reference){
this.control = reference;
}
#Override
public void run() {
try {
for(int i = 0; i < 11; i++){
//Monitor the is running flag to see if it should still run
if(control.isRunning == false){
control.reset();
break;
}
control.updateProgress(i * 10);
Thread.sleep(3000);
}
control.reset();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) throws InterruptedException {
// Create and set up the window.
JFrame frame = new JFrame("LabelDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Add content to the window.
frame.add(new Controller().view);
// Display the window.
frame.pack();
frame.setVisible(true);
}
}
I want to setText from within a Thread.
This is my code of the Thread:
private class GenerateThread implements Runnable {
public void run(){
// generate the first music
music = generate(prevmusic, prevmusic.length);
prevmusic = music;
// write the midi
writeMidi(music, song);
textOut.setText("Initialising...");
});
}
}
in my main code, I use
Thread t = new Thread(new GenerateThread());
t.start();
It does not allow me to setText from within the thread.
Following some posts on internet, I have tried using a handler, but that gave me errors, I think I am double defining Runnable this way.
Handler handler (before main)
private class GenerateThread implements Runnable {
public void run(){
handler.post(new Runnable() {
// generate the first music
music = generate(prevmusic, prevmusic.length);
prevmusic = music;
// write the midi
writeMidi(music, song);
textOut.setText("Initialising...");
});
}
}
How can I setText from within the Thread? Thanks!
besides runOnUiThread there is also View#post(Runnable) which I would prefer here because you don't need ugly looking references to the outer Activity (MyActivity.this.runOnUiThread()).
private class GenerateRunnable implements Runnable {
public void run() {
// this code is executed in a background thread.
// generate the first music
music = generate(prevmusic, prevmusic.length);
prevmusic = music;
// write the midi
writeMidi(music, song);
textOut.post(new Runnable() {
public void run() {
// this code is executed on the UI thread.
textOut.setText("Initialising...");
}
});
}
}
#Override
protected void onResume() {
super.onResume();
new Thread(new GenerateRunnable()).start();
}
Also don't confuse Runnable and Thread. A Runnable is just an ordinary class with a run() method. It can be and often is executed on a new Thread. If you want you can also make GenerateThread a real Thread like so:
private class GenerateThread extends Thread {
#Override
public void run() {
// code here.
}
}
// start somewhere
new GenerateThread().start();
And besides using classic Thread you could also think about using AsyncTask since that is made exactly for tasks that do something long running and need to update the UI afterwards or when there is progress.
One can only update the UI from the UI thread. runOnUiThread will allow you to run an action on the UI thread the next time it executes. You can do something like:
runOnUiThread(new Runnable() {
public void run() {
textOut.setText("Initialising...");
}
});
EDIT:
private class GenerateThread implements Runnable {
public void run(){
// generate the first music
music = generate(prevmusic, prevmusic.length);
prevmusic = music;
// write the midi
writeMidi(music, song);
// Update the UI
MyActivity.this.runOnUiThread(new Runnable() {
public void run() {
textOut.setText("Initialising...");
}
});
}
}