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java:concurrency_intro [2015/03/24 13:47] gthanos [Επανενεργοποίηση ενός νήματος μέσω της μεθόδου interrupt()] |
java:concurrency_intro [2015/03/24 14:01] gthanos [Περιμένοντας ένα νήμα να ολοκληρώσει μέσω της μεθόδου join()] |
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* **t.join(long millis):** μέχρι το νήμα t να τερματίσει ή περίμενε για **millis** milliseconds. | * **t.join(long millis):** μέχρι το νήμα t να τερματίσει ή περίμενε για **millis** milliseconds. | ||
* **t.join(long millis, int nanos):** μέχρι το νήμα t να τερματίσει ή περίμενε για **millis+nanos/1000000** milliseconds. | * **t.join(long millis, int nanos):** μέχρι το νήμα t να τερματίσει ή περίμενε για **millis+nanos/1000000** milliseconds. | ||
+ | |||
+ | Όπως και η μέθοδος sleep() η μέθοδος join() δύναται να διακοπεί από ένα [[http://docs.oracle.com/javase/7/docs/api/java/lang/InterruptedException.html|InterruptedException()]]. | ||
+ | |||
+ | ===== Εφαρμόζοντας τις μεθόδους sleep()/interrupt()/join() σε ένα παράδειγμα ===== | ||
+ | |||
+ | Δείτε το παρακάτω παράδειγμα εκτέλεσης δύο νημάτων, το οποίο χρησιμοποιεί τις μεθόδους sleep(), interrupt() και join() | ||
+ | |||
+ | <code java MessageLoops.java> | ||
+ | public class MessageLoop implements Runnable { | ||
+ | public void run() { | ||
+ | String importantInfo[] = { | ||
+ | "Mares eat oats", | ||
+ | "Does eat oats", | ||
+ | "Little lambs eat ivy", | ||
+ | "A kid will eat ivy too" | ||
+ | }; | ||
+ | try { | ||
+ | for (int i = 0; | ||
+ | i < importantInfo.length; | ||
+ | i++) { | ||
+ | // Pause for 4 seconds | ||
+ | Thread.sleep(4000); | ||
+ | // Print a message | ||
+ | SimpleThreads.threadMessage(importantInfo[i]); | ||
+ | } | ||
+ | } catch (InterruptedException e) { | ||
+ | SimpleThreads.threadMessage("I wasn't done!"); | ||
+ | } | ||
+ | } | ||
+ | } | ||
+ | </code> | ||
+ | |||
+ | <code java SimpleThreads.java> | ||
+ | public class SimpleThreads { | ||
+ | |||
+ | // Display a message, preceded by | ||
+ | // the name of the current thread | ||
+ | public static void threadMessage(String message) { | ||
+ | String threadName = | ||
+ | Thread.currentThread().getName(); | ||
+ | System.out.format("%s: %s%n", | ||
+ | threadName, | ||
+ | message); | ||
+ | } | ||
+ | |||
+ | public static void main(String args[]) | ||
+ | throws InterruptedException { | ||
+ | |||
+ | // Delay, in milliseconds before | ||
+ | // we interrupt MessageLoop | ||
+ | // thread (default one hour). | ||
+ | long patience = 1000 * 60 * 60; | ||
+ | |||
+ | // If command line argument | ||
+ | // present, gives patience | ||
+ | // in seconds. | ||
+ | if (args.length > 0) { | ||
+ | try { | ||
+ | patience = Long.parseLong(args[0]) * 1000; | ||
+ | } catch (NumberFormatException e) { | ||
+ | System.err.println("Argument must be an integer."); | ||
+ | System.exit(1); | ||
+ | } | ||
+ | } | ||
+ | |||
+ | threadMessage("Starting MessageLoop thread"); | ||
+ | long startTime = System.currentTimeMillis(); | ||
+ | Thread t = new Thread(new MessageLoop()); | ||
+ | t.start(); | ||
+ | |||
+ | threadMessage("Waiting for MessageLoop thread to finish"); | ||
+ | // loop until MessageLoop | ||
+ | // thread exits | ||
+ | while (t.isAlive()) { | ||
+ | threadMessage("Still waiting..."); | ||
+ | // Wait maximum of 1 second | ||
+ | // for MessageLoop thread | ||
+ | // to finish. | ||
+ | t.join(1000); | ||
+ | if (((System.currentTimeMillis() - startTime) > patience) | ||
+ | && t.isAlive()) { | ||
+ | threadMessage("Tired of waiting!"); | ||
+ | t.interrupt(); | ||
+ | // Shouldn't be long now | ||
+ | // -- wait indefinitely | ||
+ | t.join(); | ||
+ | } | ||
+ | } | ||
+ | threadMessage("Finally!"); | ||
+ | } | ||
+ | }</code> | ||
+ | |||