Java threads with timing implementation

Question

I have this thread class I am trying to work with.

public class Execution implements Runnable {
public String name;
public double time;
public double timeToDisplay;

public Execution(String name, double et){
   this.name = name;
   this.time = (et*1000);
}
public void run(){
try{


}catch(Exception e){}
}

/**
 * @return the timeToDisplay
 */
public double getTimeToDisplay() {
    return timeToDisplay;
}

/**
 * @param timeToDisplay the timeToDisplay to set
 */
public void setTimeToDisplay(double timeToDisplay) {
    this.timeToDisplay = timeToDisplay;
}
}

I am trying to get the variable timeToDisplay to change every milisecond that the thread runs. The thread is supposed to run for a set amount of et(execution time). All I need the task to do is run according to the execution time and assign the current time to timeToDisplay Variable.

So this code is the task (Runnable). What's running this runnable? — Cruncher, Nov 27 '13 at 19:08
The task is not complicated all it has to do is run for the execution time. I was required to design a CPU scheduler that actually runs tasks. The tasks are not required to do anything except run. I have my CPU scheduler set up all I have to do is run the task for the amount of execution time. But i need the variable timeToDisplay to show when the task is running and for how long it is running. — TerNovi, Nov 27 '13 at 19:11

benjamin.d · Answer 1 · 2013-11-27T19:26:02.937

0

I am not sure that is what you expect, but:

public void run() {
    try { 
        while(true) {
           timeToDisplay++;
           Thread.sleep(1);
       }
    } catch (Exception e) {
    }
  }

You may need to synchronize your get and set methods, depending on what you are trying to achieve.

edited Nov 27 '13 at 19:26

answered Nov 27 '13 at 19:13

benjamin.d

2,801
3
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I need the thread to run for et though... and setTimeToDisplay value is suppose to change concurrently every milisecond the thread runs – TerNovi Nov 27 '13 at 19:19
I edited the post. The timeToDisplay value gets incremented every millisecond. Is that what you need ? – benjamin.d Nov 27 '13 at 19:27
Let me check if this will work. It might work they way i need it too. – TerNovi Nov 27 '13 at 19:28
How can I detect if the task has stopped running? – TerNovi Nov 27 '13 at 19:29

score 0 · Accepted Answer · answered Nov 27 '13 at 19:28

0

Here is a sample of a simple scheduled job with comments. Feel free to ask for details.

public class Execution implements Runnable {
    public String name;

    protected long startedAtMs;

    // total timeout in ms
    protected long timeoutMs;


    // rate: 1 execution per 2 ms
    private long rateMs = 2;

    // when was the previousExecution
    private long prevExecutionMs;

    // action to run each 1 ms
    protected Runnable action;

    public Execution(String name, double et, Runnable action) {
        this.name = name;
        this.action = action;
        this.timeoutMs = (long) (et * 1000);

    }

    public void run() {
        startedAtMs = System.currentTimeMillis();
        prevExecutionMs = startedAtMs;

        while (true) {
            // check if the job was interrupted
            if (Thread.interrupted()) {
                return;
            }

            long now = System.currentTimeMillis();

            // check if it's time to finish
            if (now - startedAtMs > timeoutMs) {
                break;
            }

            // check if it's time to run the action
            if(now - prevExecutionMs > rateMs){
                // run the action
                action.run();
                // update the executed time
                prevExecutionMs = now;
            }
        }

    }

    // this getter could be used to get the running time
    public double getTimeToDisplay() {
        return (System.currentTimeMillis() - startedAtMs) / 1000D;
    }

    public static void main(String[] args) throws InterruptedException {
        Thread thread = new Thread(new Execution("exec", 0.5, new Runnable() {
            @Override
            public void run() {
                System.out.println(new Date());
            }
        }));

        //starts the thread
        thread.start();

        //waits to finish
        thread.join();

        System.out.println("Done!");
    }
}

answered Nov 27 '13 at 19:28

Andrey Chaschev

16,160
5
51
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wow thank you, this is sorta what I needed, I just have to modify the code. What does the join commad do though? – TerNovi Nov 27 '13 at 20:13
Join will wait for a thread to finish. After you start a thread there are two execution line being run simultaneously - one is `main()` and the other is `Execution.run`. If you don't call `join()` in a `main()` thread, it will quit immediately without waiting for `Execution.run` to finish. The problem is that with `main()` finishing, the whole app will exit, so the thread `Execution.run` will quit in the very beginning. To prevent that `main()` waits for `Execution.run` to finish. – Andrey Chaschev Nov 27 '13 at 20:19
ok. I am now trying: Thread t1 = new Thread(new Execution(Name1,et1, new Runnable(){ @Override public void run() { p1RunningState.setText("Running"); } })); t1.start(); if(t1.isAlive()){ p1RunningState.setText("Running"); } t1.join(); p1RunningState is simply a jLabel. I want it to display running while the process is running. – TerNovi Nov 27 '13 at 20:42
But i seem to have the logic reversed. It will only change to whats inside the run statement after the task has finished. I don't fully understand the code may you can help @Andrey Chaschev – TerNovi Nov 27 '13 at 20:44
sorry i fixed it right under so you can see what i was trying to show you. – TerNovi Nov 27 '13 at 20:46
I'm afraid that the SO's editing system won't let you modify the answer. I don't quite understand how setting a label could not work for you. You just set it at the beginning and at the end of your run... You could post this as a different question, but be aware though that moderators might close it because of the rules - multiple questions for the same task are frowned upon. – Andrey Chaschev Nov 27 '13 at 21:08
For example, if the process is running it shows its stopped, but if it stopped then it shows it's running. – TerNovi Nov 27 '13 at 21:10
Ah, I see. You need to update it via `SwingUtilities.invokeLater`: http://stackoverflow.com/questions/7196889/swingutilities-invokelater. – Andrey Chaschev Nov 27 '13 at 21:15

score 0 · Answer 3 · answered Nov 27 '13 at 20:46

Thread t1 = new Thread(new Execution(Name1,et1, new Runnable(){
                @Override
                public void run() {
                    p1RunningState.setText("Running");
                }
                 }));
                t1.start();

                if(!(t1.isAlive())){
                    p1RunningState.setText("Stopped");
                }
                t1.join();

Java threads with timing implementation

3 Answers3