Thread Lifecycle: Creation, Execution, and Termination Essentials Quiz

Explore essential concepts of thread lifecycle stages, including how threads are created, executed, and terminated in modern programming. This quiz is designed to reinforce your understanding of thread states, transitions, and best practices for multithreaded application development.

1. Thread Creation Basics

   Which action typically marks the beginning of a new thread’s lifecycle in a program?

   1. Terminating the main process
   2. Invoking a run() method
   3. Instantiating a thread object
   4. Entering the waiting state

   Explanation: The thread lifecycle begins when a thread object is instantiated, preparing the thread for execution. Invoking run() alone does not start a new thread; it simply calls a method without creating a separate thread of execution. Terminating the main process does not create a thread, and entering the waiting state can only happen after the thread has been started.

2. Thread Starting Procedure

   After a thread object is created, what must happen for the thread to start executing independently?

   1. Call sleep() on the thread
   2. Call the start() method
   3. Directly invoke the run() method
   4. Set the thread priority

   Explanation: Calling the start() method is required to create a new, concurrent thread of execution. The sleep() method only pauses an active thread, and directly invoking run() does not start a new thread but runs the method in the current context. Setting thread priority may influence scheduling but does not initiate execution.

3. Thread Execution State

   When a thread is actively running its code, what is this stage called in its lifecycle?

   1. Terminated state
   2. New state
   3. Runnable state
   4. Blocked state

   Explanation: The runnable state is when a thread is ready and eligible to run, often actively executing its code. The blocked state occurs when a thread is waiting for a resource, and the new state is before the thread has started. Terminated state means the thread has finished execution.

4. Thread Waiting Scenario

   In which scenario does a thread commonly enter the waiting state?

   1. When it is actively executing instructions
   2. When its run() method completes
   3. While waiting for another thread to finish
   4. When it is first created

   Explanation: A thread enters the waiting state when it is paused until certain conditions are met, such as waiting for another thread to finish via mechanisms like join(). Completion of the run() method ends the thread, not causes waiting. A newly created thread is not yet waiting, and active execution is the runnable state.

5. Blocked State Details

   What typically causes a thread to enter the blocked state during execution?

   1. It tries to acquire a locked resource
   2. It is started by the main thread
   3. It is assigned a higher priority
   4. It finishes all tasks

   Explanation: A thread enters the blocked state when it tries to access a resource that is currently unavailable or locked by another thread. Finishing tasks leads to termination, not blocking. Being started or assigned a higher priority does not cause blocking; these are unrelated to resource contention.

6. Thread Termination

   Which method or event typically signals the end of a thread’s lifecycle?

   1. Calling wait() indefinitely
   2. Assigning it to null
   3. The run() method returns
   4. Raising its priority

   Explanation: A thread’s lifecycle ends when its run() method returns, signifying completion. Calling wait() indefinitely only pauses the thread but does not terminate it. Assigning the thread to null or raising priority does not directly affect its existence or state.

7. Thread Reusability

   Can a thread object be restarted after its run() method has completed and it has terminated?

   1. No, a terminated thread cannot be restarted
   2. Yes, after calling wait()
   3. Yes, after assigning a new run() method
   4. Yes, by invoking start() again

   Explanation: Once a thread has terminated, it cannot be started again; a new thread object must be created for fresh execution. Invoking start() or assigning a new run() to a terminated thread will not restart it. The wait() method only affects threads in execution, not terminated ones.

8. Thread Sleep Behavior

   What happens to a thread when the sleep() method is called within its code?

   1. It enters the terminated state
   2. It returns to the new state
   3. It pauses execution temporarily
   4. It destroys the thread object

   Explanation: Calling sleep() causes a thread to temporarily pause without giving up resource ownership, resuming after the specified time. Termination only happens when execution completes. The new state is an initial state, and the thread object is not destroyed by sleeping.

9. Daemon Thread Characteristic

   Which best describes a daemon thread in a program’s execution lifecycle?

   1. A thread that cannot terminate
   2. A thread that always runs before the main thread
   3. A thread created using the sleep() method
   4. A thread that runs in the background and ends when all user threads end

   Explanation: Daemon threads are background threads that automatically terminate when all user (non-daemon) threads finish. Daemon threads can terminate, so the first option is wrong. Running before the main thread is not guaranteed, and daemon threads are not created by sleep().

10. Thread Lifecycle Transition

    What transition occurs when a started thread completes its run() method?

    1. Runnable to Terminated
    2. Blocked to New
    3. New to Runnable
    4. Waiting to Runnable

    Explanation: When a thread finishes its run() method, it moves from the runnable state to the terminated state, ending its lifecycle. Blocked to new and waiting to runnable are different transitions unrelated to method completion. The new to runnable transition occurs when a thread is first started, not when it terminates.