第244題

Given:
1. public class TestSeven extends Thread{
2. private static int x;
3. public synchronized void doThings(){
4. int current = x;
5. current++;
6. x = current;
7. }
8. public void run(){
9. doThings();
10. }
11. }

Which statement is true?

A. Compilation fails.
B. An exception is thrown at runtime.
C. Synchronizing the run() method would make the class thread-safe.
D. The data in variable "x" are protected from concurrent access problems.
E. Declaring the doThings() method as static would make the class thread-safe.
F. Wrapping the statements within doThings() in a synchronized(new Object()){} block would make the
class thread-safe.

答案：E
參考：13-4 執行緒的同步性與安全性