Question

Please help with Java test questions, I will post the rest of the question in separate post.

		Question 1 Consider the following program: public class CountDownApp3 {     public static void main(String[] args)     {         Thread t1 = new CountDown();         Thread t2 = new CountDown();         t1.start();         t2.start();     } } Assuming that the CountDown class extends the Thread class, how many threads are used to run this program? a. 3 b. 2 c. 4 d. 1 Question 2 From which of the following states can a thread not be moved into the Runnable state? a. Blocked b. New c. Waiting d. Terminated    Question 3 How long will a thread that executes the following statement sleep? Thread.sleep(50); a. none of the above b. at most 50 milliseconds c. at least 50 milliseconds d. exactly 50 milliseconds Question 4 To acquire a lock on an object, you can call a. the notify method b. a synchronized method c. the lock method d. the wait method    Question 5 What Java component controls the execution of threads? a. thread scheduler b. task controller c. run scheduler d. execution scheduler

Answer 1

Question 1:
The answer is Option B(2).
There are two threads mentioned in the code snippet(t1 and t2) which are started. So two threads used in the code snippet.

Question 2:
The answer is Option D(Terminated)
Once a Thread has been terminated it cannot be moved into the Runnable state. Whereas The thread can be moved from Blocked, New or waiting state.

Question 3:
The answer is Option D(Exactly 50 Milliseconds)
Thread.sleep() method is used to pause thread execution for a particular period of Time. The time can be specified in Milliseconds. In the above example(Thread.sleep(50)) it will stop the execution for 50 milliseconds.

Question 4:
The answer is Option B(Synchronized Method)
An object can be locked itself after executing the synchronized method.

Question 5:
The answer is Option A(Thread Scheduler)
Thread scheduler will decide which thread to execute. It will ensure that only one thread can be run at a time.