Why does Thread.isInterrupted () always return false?

by

This behaviour is typically documented in methods that throw that exception. For example, the javadoc for Object.wait() says:

“InterruptedException – if any thread interrupted the current thread before or while the current thread was waiting for a notification. The interrupted status of the current thread is cleared when this exception is thrown.“

Indeed, the javadoc for the exception itself says this:

“Occasionally a method may wish to test whether the current thread has been interrupted, and if so, to immediately throw this exception. The following code can be used to achieve this effect:

if (Thread.interrupted())  // Clears interrupted status!
     throw new InterruptedException();

Note how they emphasize that the flag should be cleared before the exception is thrown.

Why was it designed to work like this? You’d have to ask the designers, but I expect they figured that an exception handler should handle the situation, and that there should therefore be no need for the flag to still be set at that point. (If the handler doesn’t fully handle the situation it can either rethrow the exception, or call Thread.getCurrentThread.interrupt() to set the flag again.)

More Related Contents:

  1. Why is creating a Thread said to be expensive?
  2. Why is i++ not atomic?
  3. Synchronization vs Lock
  4. Java Wait and Notify: IllegalMonitorStateException
  5. Are static variables shared between threads?
  6. How do synchronized static methods work in Java and can I use it for loading Hibernate entities?
  7. Prime numbers by Eratosthenes quicker sequential than concurrently?
  8. Is iterating ConcurrentHashMap values thread safe?
  9. How to solve the “Double-Checked Locking is Broken” Declaration in Java?
  10. Executors.newCachedThreadPool() versus Executors.newFixedThreadPool()
  11. Is it safe to get values from a java.util.HashMap from multiple threads (no modification)?
  12. Java’s Fork/Join vs ExecutorService – when to use which?
  13. What is mutex and semaphore in Java ? What is the main difference?
  14. CountDownLatch vs. Semaphore
  15. Parallel execution of directed acyclic graph of tasks
  16. Javafx: Difference between javafx.concurent and Platform.runLater?
  17. Simplest and understandable example of volatile keyword in Java
  18. Programmatic deadlock detection in java
  19. When should we use Java’s Thread over Executor?
  20. Why does java.util.concurrent.ArrayBlockingQueue use ‘while’ loops instead of ‘if’ around calls to await()?
  21. Run Java Threads sequentially
  22. WAITING at sun.misc.Unsafe.park(Native Method)
  23. ThreadPoolExecutor Block When its Queue Is Full?
  24. Java : Does wait() release lock from synchronized block
  25. How Threadpool re-use Threads and how it works
  26. What is the most frequent concurrency issue you’ve encountered in Java? [closed]
  27. Concurrent JUnit testing
  28. Handling Exceptions for ThreadPoolExecutor
  29. Setting Ideal size of Thread Pool [duplicate]
  30. ExecutorCompletionService? Why do need one if we have invokeAll?

Leave a Comment