public class ThreadDemo {
synchronized void a() { actBusy(); }
static synchronized void b() { actBusy(); }
static void actBusy() {
try { Thread.sleep(1000); }
catch (InterruptedException e) {}
}
public static void main(
String[] args) {
final ThreadDemo x = new ThreadDemo();
final ThreadDemo y = new ThreadDemo();
Runnable runnable = new Runnable() {
public void run() {
int option = (int) (Math.random() * 4);
switch (option) {
case 0: x.a(); break;
case 1: x.b(); break;
case 2: y.a(); break;
case 3: y.b(); break;
} }
};
Thread thread1 = new Thread(runnable);
Thread thread2 = new Thread(runnable);
thread1.start();
thread2.start();
} }
Which of the following pairs of method invocations could NEVER be executing at the same
time?
Answer is
A , F and H.
How ? Please Explain me with Details
