Задача на собеседовании

[valyakol]

Пример задачи достаточно необычной, которую мне задали.

Comments

[magicprinc]

Здорово, вы помните про новые классы и их методы ;-/

На самом деле решение зависит от общей задачи, в самом простом случае я бы сделал "классически":

public static class OriginalTimeLimiter implements Runnable {
private final Original o;
private final Object in;
private Object result;
private Exception exception;
private boolean done;

private OriginalTimeLimiter (final Original o, final Object in) {
this.o = o; this.in = in;
}//new

@Override public void run () {
Object r; Exception ex; boolean dn = false;

try {
r = o.invoke(in);
ex = null; dn = true;

} catch (Exception e) {
r = null; ex = e;
}

synchronized (this) {
result = r; exception = ex; done = dn;
}
}//run

private synchronized Object get () throws MyException, InterruptedException {
if (exception instanceof MyException) {
throw (MyException) exception;
}

if (exception instanceof RuntimeException) {
throw (RuntimeException) exception;
}

if (!done) {
throw new InterruptedException("timeout");
}

return result;//can be null, if invoke result can be null
}//get

public static Object invoke (Original o, Object in, int timeSeconds) throws MyException, InterruptedException {
final OriginalTimeLimiter r = new OriginalTimeLimiter(o, in);
final Thread t = new Thread(r);
t.start();

try {
t.join(timeSeconds*1000L);
} catch (InterruptedException e) {
t.interrupt();
Thread.currentThread().interrupt();
throw e;
}

final Object tmp = r.get();
t.interrupt();
return tmp;
}//invoke
}//OriginalTimeLimiter

@Test public void testTimeout () throws MyException, InterruptedException {
final Original o = new Original();

try {
OriginalTimeLimiter.invoke(o, null, 1);
fail("Null должен генерировать MyException");
} catch (InterruptedException e) {
fail("Null должен генерировать MyException");
} catch (MyException e) {}

assertEquals("", OriginalTimeLimiter.invoke(o, "", 1));
assertEquals("[test]", OriginalTimeLimiter.invoke(o, "test", 3));
assertEquals("{1}", OriginalTimeLimiter.invoke(o, 1, 3));

try {
OriginalTimeLimiter.invoke(o, "ops", 1);
fail("Null должен генерировать InterruptedException");
} catch (InterruptedException e) {
assertEquals("timeout", e.getMessage());
} catch (MyException e) {
fail("Null должен генерировать InterruptedException");
}

try {
assertEquals(20000000L, OriginalTimeLimiter.invoke(o, 1, 1));
fail("Null должен генерировать InterruptedException");
} catch (InterruptedException e) {
assertEquals("timeout", e.getMessage());
} catch (MyException e) {
fail("Null должен генерировать InterruptedException");
}
}//testTimeout