java - call Thread.interrupt() but Thread is still working -


this question has answer here:

java code:

public class test {     public static void main(string[] args) throws interruptedexception {         customer customer = new customer();         customer.start();  // start customer         thread.sleep(5000);         customer.interrupt();  // interrupt     }  }  class customer extends thread {      @override     public void run() {         while (!thread.currentthread().isinterrupted()) {              system.out.println("test interrupted +++++");             try {                 thread.sleep(500);             } catch (interruptedexception e) {                 e.printstacktrace();             }         }     }  }

i call customer.interrupt() customer still working;
console result：

test interrupted +++++ .... test interrupted +++++ java.lang.interruptedexception: sleep interrupted test interrupted +++++     @ java.lang.thread.sleep(native method)     @ com.yitai.common.redisqueue.customer.run(test.java:22) test interrupted +++++ test interrupted +++++ ....  //more

if change code in way : add thread.currentthread().interrupt() in catch

try {     thread.sleep(500); } catch (interruptedexception e) {     thread.currentthread().interrupt();  // add     e.printstacktrace(); }

customer stoped why?
console result:

test interrupted +++++ ....  test interrupted +++++ java.lang.interruptedexception: sleep interrupted     @ java.lang.thread.sleep(native method)     @ com.yitai.common.redisqueue.customer.run(test.java:22) // end

what happening calling thread.interrupt() clears thread's interrupted status if thread waiting, causing loop continue. javadoc (my emphasis):

if thread blocked in invocation of wait(), wait(long), or wait(long, int) methods of object class, or of join(), join(long), join(long, int), sleep(long), or sleep(long, int), methods of class, interrupt status cleared , receive interruptedexception.

to put way, if possible thread receive interruptedexception (because in wait state) exception sent , interrupt status cleared. interrupt status set when not possible synchronously deliver exception.

you need account in program's logic terminating thread, assuming intention. need correctly handle both possibilities.


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