I am using org.eclipse.core.runtime.jobs.JOB to execute backgrounds task that also gathers data from UI controls.
I want to "block" until job is finished (the trigger for the JOB is some ui button event)
Job job = new Job("Job") {
protected IStatus run(IProgressMonitor arg0) {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
for (int i = 0; i < 100; i++) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {}
System.out.println(i);
}
}
});
return Status.OK_STATUS;
}
};
job.schedule();
job.join(); //<-- Doesn't block!!!
if (job.getResult().isOK())
System.out.println("success"); //<-- Result is ok!!
else
System.out.println("failed");
Related
I have a Java swing UI where I need to disable a button on the UI if I could not detect an active internet connection.
The code function properly so far, but when I get disconnected from the internet, it does not retrigger the method to update the boolean flag.
How can I add an event on that flag to let my button consume it during the lifetime of the application?
public class Main {
private static JButton button;
private static boolean testButtonEnabled;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
/*
* function that returns true/false if connected to the internet
*/
if(Utils.isConnectedToInternet()) {
logger.debug("System is connected to the internet");
testButtonEnabled=true;
} else {
logger.debug("System is not connected to the internet");
testButtonEnabled=false;
}
Main window = new Main();
window.frame.setVisible(true);
button = new JButton("my button");
/*
* set the internet status
*/
button.setVisible(testButtonEnabled);
}
}
}
}
Again, this code:
SwingWorker<Void, String> worker = new SwingWorker<Void, String>()
{
public Void doInBackground()
{
while(true)
{
try {
isConnectedToInternet = Utils.isConnectedToInternet();
if (isConnectedToInternet) {
btn_online2.setEnabled(isConnectedToInternet);
} else {
btn_online2.setEnabled(isConnectedToInternet);
}
logger.debug("Internet connection status: " + isConnectedToInternet);
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
worker.execute();
is dangerous since it makes mutational changes to a Swing component from a background thread. While this code may work 95% of the time, it can fail in unpredicatable ways and at unpredicatable times. Better to only mutate Swing components on the event thread. For instance, even this would be better:
SwingWorker<Void, String> worker = new SwingWorker<Void, String>() {
#Override
public Void doInBackground() {
while(true) {
try {
isConnectedToInternet = Utils.isConnectedToInternet();
// note that there is no need for the if/else block
SwingUtilities.invokeLater(() -> {
btn_online2.setEnabled(isConnectedToInternet);
});
logger.debug("Internet connection status: " + isConnectedToInternet);
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
worker.execute();
or better still, using SwingWorker's publish/process:
SwingWorker<Void, Boolean> worker = new SwingWorker<Void, Boolean>() {
#Override
public Void doInBackground() {
while(true) {
try {
isConnectedToInternet = Utils.isConnectedToInternet();
// note that there is no need for the if/else block
publish(Utils.isConnectedToInternet());
logger.debug("Internet connection status: " + isConnectedToInternet);
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
#Override
protected void process(List<Boolean> chunks) {
for (Boolean chunk : chunks) {
btn_online2.setEnabled(chunk);
}
}
};
worker.execute();
I was able to resolve using the following method in the initialize() of the frame.
Adding that change part of the swingworker allowed the button to check the flag and assign it to itself whenever it changes.
Now whenever the internet is disconnected the button is disabled and whenever connected the button is enabled.
SwingWorker<Void, String> worker = new SwingWorker<Void, String>()
{
public Void doInBackground()
{
while(true)
{
try {
isConnectedToInternet = Utils.isConnectedToInternet();
if (isConnectedToInternet) {
btn_online2.setEnabled(isConnectedToInternet);
} else {
btn_online2.setEnabled(isConnectedToInternet);
}
logger.debug("Internet connection status: " + isConnectedToInternet);
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
worker.execute();
In my SWT GUI, I would like to have a button that kicks off a job and while running that job, update a textbox that will show a log of the events of that job. However, my textbox does not update until the end of my asyncExec() call. In the example below, I would like for my textbox to be updated every second, but instead it gets all of the updates at once after 10 full seconds when it finishes executing.
Is there a way to achieve this?
private void UpdateUI()
{
Display.getDefault().asyncExec(new Runnable() {
#Override
public void run()
{
StringBuilder sb = new StringBuilder();
for(int i=1; i<=10; i++)
{
sb.append("Running iteration " + i + "\n");
txtLogBox.setText(sb.toString());
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}});
}
You're sleeping in the UI thread. You need to do your long-running work in a different thread and only post updates to the UI thread using asyncExec. For example:
new Thread(new Runnable() {
public void run()
{
StringBuilder sb = new StringBuilder();
for(int i=1; i<=10; i++)
{
sb.append("Running iteration " + i + "\n");
final String result = sb.toString();
Display.getDisplay().asyncExec(new Runnable() {
public void run()
{
txtLogBox.setText(result);
}
});
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
I need stop thread and handler when my progress bar reaches 0 from 100 when thread runs the progress bar reaches but the progressStatus value going in negative please help me to stop thread after progress bar reaches 0
new Thread(runn =new Runnable() {
public void run() {
while (progressStatus <= 100) {
progressStatus += doWork();
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
// Update the progress bar
handler.post(runn1=new Runnable() {
public void run() {
bar.setProgress(progressStatus);
i=-1;
if(bar.getProgress()==0)
{
handler.removeCallbacks(runn);
handler.removeCallbacks(runn1);
System.out.println("Reached");
congrats.setVisibility(View.VISIBLE);
restart.setVisibility(View.VISIBLE);
rightbutton.setVisibility(View.GONE);
wrongbutton.setVisibility(View.GONE);
}
}
});
}
}
private int doWork() {
return i;
}
}).start();
your program is not thread safe, you actually reading and writing a variable (progressStatus) from two different threads, you must avoid doing that or if you want to do that you must use synchronized block. In order to solve your problem you can do this way:
Thread t;
progressStatus = 100;
t = new Thread(runn =new Runnable() {
public void run() {
while (!Thread.currentThread().isInterrupted()) {
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
return;
}
// Update the progress bar
handler.post(runn1=new Runnable() {
public void run() {
bar.setProgress(progressStatus);
progressStatus=progressStatus-1;
if(bar.getProgress()==0)
{
handler.removeCallbacks(runn);
handler.removeCallbacks(runn1);
System.out.println("Reached");
congrats.setVisibility(View.VISIBLE);
restart.setVisibility(View.VISIBLE);
rightbutton.setVisibility(View.GONE);
wrongbutton.setVisibility(View.GONE);
t.interrupt();
}
}
});
another way that i recommend you is using ScheduledThreadPoolExecutor with the function scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit). something like:
final ScheduledThreadPoolExecutor myTimer = new ScheduledThreadPoolExecutor(1);
myTimer.scheduleAtFixedRate(new Runnable() {
#Override
public void run() {
getActivity().runOnUiThread(new Runnable(){
#Override
public void run(){
}
});
}
}
}, 0,10, TimeUnit.MILLISECONDS);
and in order to close it use myTimer.shutdownNow();
Iam making app for listening .mp3 words in greek language and displaying them after 2000ms but when i pause thread and then notify() back thread never runs again... TextView is changing every 2000ms but when i pause it and notify() run() block is not executing anything anymore and app crashes.. What iam doing wrong ?
class MyinnerThread implements Runnable {
String name;
Thread tr;
boolean suspendFlag;
int i = 0;
MyinnerThread(String threadname) {
name = threadname;
tr = new Thread(this, name);
suspendFlag = false;
tr.start();
}
public void run() {
try {
while(!suspendFlag){
runOnUiThread(new Runnable() {
#Override
public void run() {
if(i == 0){tv1.setText("trhead1");}
if(i == 1){tv2.setText("trhead2");}
if(i == 2){tv3.setText("trhead3");}
if(i == 3){tv4.setText("trhead4");}
if(i == 4){tv5.setText("trhead5");}
if(i == 5){tv6.setText("trhead6");}
if(i == 6){tv7.setText("trhead7");}
if(i == 7){tv8.setText("trhead8");}
synchronized(signal) {
while(suspendFlag) {
try {
signal.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
});
Thread.sleep(2000);
i++;
}
} catch (InterruptedException e) {
System.out.println(name + " interrupted.");
}
}
void mysuspend() {
suspendFlag = true;
}
void myresume() {
synchronized(signal) {
suspendFlag = false;
signal.notify();
}
}
}
EDIT: Final code here and working !
run() {
try {
while(true){
synchronized(signal) {
while(suspendFlag) {
try {
signal.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
runOnUiThread(new Runnable() {
#Override
public void run() {
//....
}
}
});
Thread.sleep(2000);
i++;
}
}
}
}
signal.wait() is called from within the UI thread (I assume, runOnUIThread will execute the given Runnable on the UI thread). This will block/freeze the UI. Take it out of the run() method and put into the threads 'main loop'.
Rethink the main loop while (!suspendFlag)! This will abort the entire task instead of just suspending it.
Finally, make suspendFlag volatile to avoid visibility issues.
In my android application I want an automatically refresh every 60 seconds. So I tried it like this:
public void refresh_check() {
Thread myThread = new Thread()
{
int counter = 0;
#Override
public void run() {
MyActivity.this.runOnUiThread(new Runnable(){
#Override
public void run() {
while (counter < 60) {
try {
Thread.sleep(1000);
counter += 1;
System.out.println("Counter: " + counter);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
refresh();
}});
super.run();
}
};
myThread.start();
}
This works in the way that it prints the counter into logcat but in my Application I get a black view. refresh() is just a function with a http request, and this works alone, so the mistake has to be in the thread at any place :/ Can someone help?
You are not utilizing the Thread correctly. Running long tasks on the UI thread is just like not using a Thread at all. To accomplish what you need you should do it like this:
public void refresh_check() {
Thread myThread = new Thread()
{
int counter = 0;
#Override
public void run() {
while (counter < 60) {
try {
Thread.sleep(1000);
counter += 1;
System.out.println("Counter: " + counter); //I think this may cause exception, if it does try removing it
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
refresh(); // In refresh(), use TextView.post(runnable) to post update the TextView from outside the UI thread or use handlers
}});
super.run();
};
myThread.start();
}
Also, take a look at AsyncTask class, it enables you to run long tasks outside UI thread (doInBackground()) as well as update UI with the result from (onPostExecute())