单项选择题
foo and bar are public references available to many other threads. foo refers to a Thread and bar is an Object. The thread foo is currently executing bar.wait(). From another thread, which statement is the most reliable way to ensue that foo will stop executing wait()?
A. foo.notify();
B. bar.notify();
C. foo.notifyAll();
D. Thread.notify();
E. bar.notiFYAll();
F. Object.notify();
相关考题
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单项选择题
void waitForSignal() { Object obj = new Object(); synchronized (Thread.currentThread()) { obj.wait(); obj.notify(); } } Which is true?()
A. This code may throw an InterruptedException.
B. This code may throw an IllegalStateException.
C. This code may throw a TimeoutException after ten minutes.
D. This code will not compile unless “obj.wait()” is replaced with “((Thread) obj).wait()”.
E. Reversing the order of obj.wait() and obj.notify() may cause this method to complete normally.
F. A call to notify() or notifyAll() from another thread may cause this method to complete normally. -
单项选择题
class Computation extends Thread { private int num; private boolean isComplete; private int result; public Computation(int num) { this.num = num; } public synchronized void run() { result = num * 2; isComplete = true; notify(); } public synchronized int getResult() { while (!isComplete) { try { wait(); } catch (InterruptedException e) { } } return result; } public static void main(String[] args) { Computation[] computations = new Computation [4]; for (int i = 0; i < computations.length; i++) { computations[i] = new Computation(i); computations[i] .start(); } for (Computation c : computations) System.out.print(c.getResult() +“ “); } } What is the result?()
A. The code will deadlock.
B. The code may run with no output.
C. An exception is thrown at runtime.
D. The code may run with output “0 6”.
E. The code may run with output “2 0 6 4‟.
F. The code may ruin with output “0 2 4 6”. -
多项选择题
public class Transfers { public static void main(String[] args) throws Exception { Record r1 = new Record(); Record r2 = new Record(); doTransfer(r1, r2, 5); doTransfer(r2, r1, 2); doTransfer(r1, r2, 1); // print the result System.out.println(”rl = “ + r1.get() +“, r2=” + r2.get()); } private static void doTransfer( final Record a, final Record b, final int amount) { Thread t = new Thread() { public void run() { new Clerk().transfer(a, b, amount); } }; t.start(); } } class Clerk { public synchronized void transfer(Record a, Record b, int amount){ synchronized (a) { synchronized (b) { a.add(-amount); b.add(amount); } } } } class Record { int num=10; public int get() { return num; } public void add(int n) { num = num + n; } } If Transfers.main() is run, which three are true?()
A. The output may be “r1 = 6, r2 = 14”.
B. The output may be “r1 = 5, r2 = 15”.
C. The output may be “r1 = 8, r2 = 12”.
D. The code may run (and complete) with no output.
E. The code may deadlock (without completing) with no output.
F. M IllegalStateException or InterruptedException may be thrown at runtime.
