SCJP考试题310-025(第二套<3>)51-91/147

Question No 54
Which statement is true?
A. If only one thread is blocked in the wait method of an object, and another thread executes the
modify on that same object, then the first thread immediately resumes execution.
B. If a thread is blocked in the wait method of an object, and another thread executes the notify
method on the same object, it is still possible that the first thread might never resume execution.
C. If a thread is blocked in the wait method of an object, and another thread executes the notify
method on the same object, then the first thread definitely resumes execution as a direct and sole
consequence of the notify call.
D. If two threads are blocked in the wait method of one object, and another thread executes the notify
method on the same object, then the first thread that executed the wait call first definitely resumes
execution as a direct and sole consequence of the notify call.
Answer: B
Question No 55
Which two CANNOT directly cause a thread to stop executing? (Choose Two)
A. Calling the yield method.
B. Calling the wait method on an object.
C. Calling the notify method on an object.
D. Calling the notifyAll method on an object.
E. Calling the start method on another Thread object.
Answer: C, D
Question No 56
Which two can be used to create a new Thread? (Choose Two)
A. Extend java.lang.Thread and override the run method.
B. Extend java.lang.Runnable and override the start method.
C. Implement java.lang.thread and implement the run method.
D. Implement java.lang.Runnable and implement the run method.
E. Implement java.lang.Thread and implement the start method.
Answer: A, D

Question No 57
Given:
1. public class SyncTest (
2. private int x;
3. private int y;
4. private synchronized void setX (int i) (x=1;)
5. private synchronized void setY (int i) (y=1;)
6. public void setXY(int 1)(set X(i); setY(i);)
7. public synchronized Boolean check() (return x !=y;)
8. )
Under which conditions will check () return true when called from a different class?
A. Check() can never return true.
B. Check() can return true when setXY is called by multiple threads.
C. Check() can return true when multiple threads call setX and setY separately.
D. Check() can only return true if SyncTest is changed to allow x and y to be set separately.
Answer: B