221. Given: 

7. void waitForSignal(){

 8. Object obj = new Object()； 

9. synchronized(Thread.currentThread()){ 

10. obj.wait()；

 11. obj.notify()； 

12. } 

13. } 

Which statement is true?
(A) This code can throw an InterruptedException.
(B) This code can throw an IllegalMonitorStateException.
(C) This code can throw a TimeoutException after ten minutes.
(D) Reversing the order of obj.wait() and obj.notify() might cause this method to complete normally.
(E) A call to notify() or notifyAll() from another thread might cause this method to complete normally.

複選題213. Given a class whose instances, when found in a collection of objects, are sorted by using the compareTo() method, which two statements are true? (choose two.) (A) The class implements java.lang.Comparable. (B) The class implements java.util.Comparator. (C) The interface used to implement sorting allows this class to define only one sort sequence. (D) The interface used to implement sorting allows this class to define many different sort sequences.

214. Given: 12. import java.util.*；13. public class Explorer3{ 14. public static void main(String[] args){ 15. TreeSet＜Integer＞ s = new TreeSet＜Integer＞()； 16. TreeSet＜Integer＞ subs = new TreeSet＜Integer＞()； 17. for(int i=606； i＜613； i++) 18. if(i%2 == 0) s.add(i)； 19. subs = (TreeSet)s.subSet(608, true, 611, true)； 20. subs.add(629)； 21. System.out.println(s + " " + subs)； 22. } 23. } What is the result? (A) Compilation fails. (B) An exception is thrown at runtime. (C) [608, 610, 612, 629] [608, 610] (D) [608, 610, 612, 629] [608, 610, 629] (E) [606, 608, 610, 612, 629] [608, 610]

215. Given: 1. import java.util.*； 2. 3. public class LetterASort{ 4. public static void main(String[] args){ 5. ArrayList＜String＞ strings = new ArrayList＜String＞()； 6. strings.add("aAaA")； 7. strings.add("AaA")； 8. strings.add("aAa")； 9. strings.add("AAaa")； 10. Collections.sort(strings)； 11. for(String s : strings){System.out.print(s + " ")；} 12. } 13. }What is the result?(A)Compilation fails.(B) aAaA aAa AAaa AaA (C)AAaa AaA aAa aAaA (D) AaA AAaa aAaA aAa(E) aAa AaA aAaA AAaa

複選題219. Given: 1. public class Threads2 implements Runnable{ 2. 3. public void run(){ 4. System.out.println("run.")； 5. throw new RuntimeException("Problem")； 6. } 7. public static void main(String[] args){ 8. Thread t = new Thread(new Threads2())； 9. t.start()； 10. System.out.println("End of method.")； 11. } 12. } Which two can be results? (Choose two.) (A) java.lang.RuntimeException: Problem (B) run. java.lang.RuntimeException: Problem (C) End of method. java.lang.RuntimeException: Problem (D) End of method. run. java.lang.RuntimeException: Problem (E) run. java.lang.RuntimeException: Problem End of method.

222. Given: 10. public class Starter extends Thread{ 11. private int x = 2； 12. public static void main(String[] args) throws Exception{ 13. new Starter().makeItSo()； 14. } 15. public Starter(){ 16. x = 5； 17. start()； 18. } 19. public void makeItSo() throws Exception{ 20. join()； 21. x = x - 1； 22. System.out.println(x)； 23. } 24. public void run(){x *= 2；} 25. } What is the output if the main() method is run? (A) 4 (B) 5 (C) 8 (D) 9 (E) Compilation fails.

223. Given: 11. class PingPong2{ 12. synchronized void hit(long n){ 13. for(int i=1; i<3; i++) 14. System.out.print(n + "-" + i + " "); 15. } 16. } 17. public dass Tester implements Runnable{ 18. static PingPong2 pp2 = new PingPong2(); 19. public static void main(String[] args){ 20. new Thread(new Tester()).start(); 21. new Thread(new Tester()).start(); 22. } 23. public void run(){pp2.hit(Thread.currentThread.getId());} 24. } Which statement is true?(A) The output could be 5-1 6-1 6-2 5-2 (B) The output could be 6-1 6-2 5-1 5-2 (C) The output could be 6-1 5-2 6-2 5-1 (D) The output could be 6-1 6-2 5-1 7-1

224. Given: 1. public class Threads4{ 2. public static void main(String[] args){ 3. new Threads4.go()； 4. } 5. public void go(){ 6. Runnable r = new Runnable(){ 7. public void run(){ 8. System.out.print("foo")； 9. } 10. }； 11. Thread t = new Thread(r)； 12. t.start()； 13. t.start()； 14. } 15. } What is the result? (A) Compilation fails. (B) An exception is thrown at runtime. (C) The code executes normally and prints "foo"； (D) The code executes normally, but nothing is printed.

複選題226. Which two statements are true? (Choose two.) (A) It is possible to synchronize static methods. (B) When a thread has yielded as a result of yield(), it releases its locks. (C) When a thread is sleeping as a result of sleep(), it releases its locks. (D) The Object.wait() method can be invoked only from a synchronized context. (E) The Thread.sleep() method can be invoked only from a synchronized context.

227. Given: 1. public class TestOne implements Runnable{ 2. public static void main (String[] args)throws Exception{ 3. Thread t = new Thread(new TestOne())； 4. t.start()； 5. System.out.pririt("Started")； 6. t.join()； 7. System.out.print("Complete")； 8. } 9. public void run(){ 10. for(int i=0； i＜4； i++){ 11. System.out.print(i)； 12. } 13. } 14. } What can be a result? (A) Compilation fails. (B) An exception is thrown at runtime. (C) The code executes and prints "StartedComplete". (D) The code executes and prints "StartedComplete0123". (E) The code executes and prints "Started0123Complete".

複選題229. Given: 1. public class TestFive{ 2. private int x； 3. public void foo(){ 4. int current = x； 5. x = current + 1； 6. } 7. public void go(){ 8. for(int i=0； i＜5； i++){ 9. new Thread(){ 10. public void run(){ 11. foo()； 12. System.out.print(x + ", ")； 13. }}.start()； 14. }} Which two changes, taken together, would guarantee the output: 1, 2, 3, 4, 5, ? (Choose two.) (A) move the line 12 print statement into the foo() method (B) change line 7 to public synchronized void go(){ (C) change the variable declaration on line 2 to private volatile int x； (D) wrap the code inside the foo() method with a synchronized(this) block (E) wrap the for loop code inside the go() method with a synchronized block synchronized(this){//for loop code here}