Threads - Thread Execution

Alive or Dead?

• the Thread class includes an isAlive() method which returns true if a thread has been started and not stopped
• a thread stops when its run() method finishes executing
• the isAlive() method returns false if the thread is new or dead
• there is no way to detect if a thread is not alive because it was never started or because it is dead
• there is also no way to detect if a live thread is Runnable or Not Runnable
• neither can a thread identify which thread started it

Why a thread might not be executing (BB pg 270)

• the thread does not have the highest priority and can't get CPU time
  Example: LowPriority
• the thread has been put to sleep via sleep() method
  Example: Sleeping
• there is more than one thread with the same priority and the JVM is switching between the threads
  Example: SamePriority
• the thread's wait() method has been invoked
  Example: Waiting
• the thread's yield() method has been invoked
  Example: Yielding
• the suspend() method has been invoked (this is a deprecated method and should no longer be used)