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I'm unable to use Thread.sleep(x) or wait(): java.lang.InterruptedException; must be caught or declared to be thrown

Posted by: admin November 2, 2017 Leave a comment

Questions:

I have tried to delay – or put to sleep – my Java program, but an error occurs.

I’m unable to use Thread.sleep(x) or wait(). The same error message appears:

unreported exception java.lang.InterruptedException; must be caught or declared to be thrown.

Is there any step required before using the Thread.sleep() or wait() methods?

Answers:

You have a lot of reading ahead of you. From compiler errors through exception handling, threading and thread interruptions. But this will do what you want:

try {
    Thread.sleep(1000);                 //1000 milliseconds is one second.
} catch(InterruptedException ex) {
    Thread.currentThread().interrupt();
}

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Answers:

As other users have said you should surround your call with a try{...} catch{...} block. But since Java 1.5 was released, there is TimeUnit class which do the same as Thread.sleep(millis) but is more convenient.
You can pick time unit for sleep operation.

try {
    TimeUnit.NANOSECONDS.sleep(100);
    TimeUnit.MICROSECONDS.sleep(100);
    TimeUnit.MILLISECONDS.sleep(100);
    TimeUnit.SECONDS.sleep(100);
    TimeUnit.MINUTES.sleep(100);
    TimeUnit.HOURS.sleep(100);
    TimeUnit.DAYS.sleep(100);
} catch (InterruptedException e) {
    //Handle exception
}

Also it has additional methods:
TimeUnit Oracle Documentation

Questions:
Answers:

Have a look at this excellent brief post on how to do this properly.

Essentially: catch the InterruptedException. Remember that you must add this catch-block. The post explains this a bit further.

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Use the following coding construct to handle exceptions

try {
  Thread.sleep(1000);
} catch (InterruptedException ie) {
    //Handle exception
}

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Answers:

Put your Thread.sleep in a try catch block

try {
    //thread to sleep for the specified number of milliseconds
    Thread.sleep(100);
} catch ( java.lang.InterruptedException ie) {
    System.out.println(ie);
}

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Answers:

When using Android (the only time when I use Java) I would recommend using a handler instead putting the thread to sleep.

final Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            Log.i(TAG, "I've waited for two hole seconds to show this!");

        }
    }, 2000);

Reference: http://developer.android.com/reference/android/os/Handler.html

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Try this:

try{

    Thread.sleep(100);
}catch(Exception e)
{
   System.out.println("Exception caught");
}

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My ways to add delay to a Java program.

public void pause1(long sleeptime) {
    try {
        Thread.sleep(sleeptime);
    } catch (InterruptedException ex) {
        //ToCatchOrNot
    }
}

public void pause2(long sleeptime) {
    Object obj = new Object();
    if (sleeptime > 0) {
        synchronized (obj) {
            try {
                obj.wait(sleeptime);
            } catch (InterruptedException ex) {
                //ToCatchOrNot
            }
        }
    }
}
public void pause3(long sleeptime) {
    expectedtime = System.currentTimeMillis() + sleeptime;
    while (System.currentTimeMillis() < expectedtime) {
        //Empty Loop   
    }
}

This is for sequential delay but for Loop delays refer to Java Delay/Wait.

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public static void main(String[] args) throws InterruptedException {
  //type code


  short z=1000;
  Thread.sleep(z);/*will provide 1 second delay. alter data type of z or value of z for longer delays required */

  //type code
}

eg:-

class TypeCasting {

  public static void main(String[] args) throws InterruptedException {
    short f = 1;
    int a = 123687889;
    short b = 2;
    long c = 4567;
    long d=45;
    short z=1000;
    System.out.println("Value of a,b and c are\n" + a + "\n" + b + "\n" + c + "respectively");
    c = a;
    b = (short) c;
    System.out.println("Typecasting...........");
    Thread.sleep(z);
    System.out.println("Value of B after Typecasting" + b);
    System.out.println("Value of A is" + a);


  }
}

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Answers:

Alternatively, if you don’t want to deal with threads, try this method:

public static void pause(int seconds){
    Date start = new Date();
    Date end = new Date();
    while(end.getTime() - start.getTime() < seconds * 1000){
        end = new Date();
    }
}

It starts when you call it, and ends when the number of seconds have passed.