121. When a thread blocks on I/O, what state does it enter?
A thread enters the waiting state when it blocks on I/O.
122. When a thread is created and started, what is its initial state?
A thread is in the ready state after it has been created and started.
123. What invokes a thread’s run() method?
After a thread is started, via its start() method or that of the Thread class, the JVM invokes the thread’s run() method when the thread is initially executed.
124. What method is invoked to cause an object to begin executing as a separate thread?
The start() method of the Thread class is invoked to cause an object to begin executing as a separate thread.
125. What is the purpose of the wait(), notify(), and notifyAll() methods?
The wait(),notify(), and notifyAll() methods are used to provide an efficient way for threads to wait for a shared resource. When a thread executes an object’s wait() method, it enters the waiting state. It only enters the ready state after another thread invokes the object’s notify() or notifyAll() methods.
126. What are the high-level thread states?
The high-level thread states are ready, running, waiting, and dead.
127. What happens when a thread cannot acquire a lock on an object?
If a thread attempts to execute a synchronized method or synchronized statement and is unable to acquire an object’s lock, it enters the waiting state until the lock becomes available.
128. How does multithreading take place on a computer with a single CPU?
The operating system’s task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.
129. What happens when you invoke a thread’s interrupt method while it is sleeping or waiting?
When a task’s interrupt() method is executed, the task enters the ready state. The next time the task enters the running state, an InterruptedException is thrown.
130. What state is a thread in when it is executing?
An executing thread is in the running state.
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