How to make a thread sleep for specific amount of time in java?

Question

I have a scenario where i want a thread to sleep for specific amount of time.

Code:

    public void run(){
        try{
            //do something
                     Thread.sleep(3000);
//do something after waking up
                }catch(InterruptedException e){
                // interrupted exception hit before the sleep time is completed.so how do i make my thread sleep for exactly 3 seconds?
                }
        }

Now how do i handle the case where the thread i am trying to run is hit with an interrupted exception before the complete of the sleep? Also does the thread wake up after being interrupted and does it go to runnable state or when is it that only after it goes to runnable does the flow go to catch block?

Answer 1

When your thread is hit by an interrupt it will go into the InterruptedException catch block. You can then check how much time the thread has spent sleeping and work out how much more time there is to sleep. Finally, instead of swallowing the exception, it is good practice to restore the interruption status so that code higher up the call stack can deal with it.

public void run(){

    //do something

    //sleep for 3000ms (approx)     
    long timeToSleep = 3000;
    long start, end, slept;
    boolean interrupted;

    while(timeToSleep > 0){
        start=System.currentTimeMillis();
        try{
            Thread.sleep(timeToSleep);
            break;
        }
        catch(InterruptedException e){

            //work out how much more time to sleep for
            end=System.currentTimeMillis();
            slept=end-start;
            timeToSleep-=slept;
            interrupted=true
        }
    }

    if(interrupted){
        //restore interruption before exit
        Thread.currentThread().interrupt();
    }
}