Example usage for java.util Deque peekLast

Introduction

In this page you can find the example usage for java.util Deque peekLast.

Prototype

E peekLast();

Source Link

Document

Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty.

Usage

From source file:org.springframework.integration.support.management.ExponentialMovingAverageRateTests.java

@Test
@SuppressWarnings("unchecked")
public void testGetTimeSinceLastMeasurement() throws Exception {
    long sleepTime = 20L;

    // fill history with the same value.
    long now = System.nanoTime() - 2 * sleepTime * 1000000;
    for (int i = 0; i < TestUtils.getPropertyValue(history, "retention", Integer.class); i++) {
        history.increment(now);/*from  w w w  .  j a va 2 s  .c  o  m*/
    }
    final Deque<Long> times = TestUtils.getPropertyValue(history, "times", Deque.class);
    assertEquals(Long.valueOf(now), times.peekFirst());
    assertEquals(Long.valueOf(now), times.peekLast());

    //increment just so we'll have a different value between first and last
    history.increment(System.nanoTime() - sleepTime * 1000000);
    assertNotEquals(times.peekFirst(), times.peekLast());

    /*
     * We've called Thread.sleep twice with the same value in quick
     * succession. If timeSinceLastSend is pulling off the correct end of
     * the queue, then we should be closer to the sleep time than we are to
     * 2 x sleepTime, but we should definitely be greater than the sleep
     * time.
    */
    double timeSinceLastMeasurement = history.getTimeSinceLastMeasurement();
    assertTrue(timeSinceLastMeasurement > sleepTime);
    assertTrue(timeSinceLastMeasurement <= (1.5 * sleepTime));
}

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From source file:uniol.apt.adt.automaton.FiniteAutomatonUtility.java

static private List<String> findAcceptedWord(DeterministicFiniteAutomaton dfa) {
    Set<DFAState> statesSeen = new HashSet<>();
    LinkedList<String> word = new LinkedList<>();
    Deque<Pair<DFAState, Iterator<Symbol>>> trace = new LinkedList<>();
    DFAState initial = dfa.getInitialState();
    trace.add(new Pair<>(initial, initial.getDefinedSymbols().iterator()));

    while (!trace.isEmpty()) {
        InterrupterRegistry.throwIfInterruptRequestedForCurrentThread();
        Pair<DFAState, Iterator<Symbol>> pair = trace.peekLast();
        if (!pair.getSecond().hasNext()) {
            trace.removeLast();/*from   www  . ja v  a2 s  . com*/
            word.pollLast();
        } else {
            Symbol symbol = pair.getSecond().next();
            DFAState nextState = pair.getFirst().getFollowingState(symbol);

            // Only follow this state if we haven't followed it yet before
            if (statesSeen.add(nextState)) {
                trace.add(new Pair<>(nextState, nextState.getDefinedSymbols().iterator()));
                word.add(symbol.getEvent());

                if (nextState.isFinalState())
                    return word;
            }
        }
    }

    return null;
}

---

From source file:uniol.apt.adt.automaton.FiniteAutomatonUtility.java

/**
 * Find a word whose prefixes (including the word) conform to a given predicate and which itself also conforms
 * to a second predicate.//w w w. j a  v  a 2  s  .c o  m
 *
 * This method uses a depth-first search. A breath-first search would use more memory.
 *
 * @param a The automaton whose accepted words should get checked.
 * @param prefixPredicate The predicate to check the prefixes.
 * @param wordPredicate The predicate to check the words.
 * @return A word which conforms to the predicates.
 */
static public List<String> findPredicateWord(FiniteAutomaton a, Predicate<List<String>> prefixPredicate,
        Predicate<List<String>> wordPredicate) {
    MinimalDeterministicFiniteAutomaton dfa = minimizeInternal(a);
    Deque<Pair<DFAState, Iterator<Symbol>>> trace = new ArrayDeque<>();
    LinkedList<String> word = new LinkedList<>();
    DFAState initial = dfa.getInitialState();
    DFAState sinkState = findSinkState(dfa);
    trace.add(new Pair<>(initial, initial.getDefinedSymbols().iterator()));

    while (!trace.isEmpty()) {
        Pair<DFAState, Iterator<Symbol>> pair = trace.peekLast();
        if (!pair.getSecond().hasNext()) {
            trace.removeLast();
            word.pollLast();
        } else {
            Symbol symbol = pair.getSecond().next();
            DFAState nextState = pair.getFirst().getFollowingState(symbol);
            if (!nextState.equals(sinkState)) {
                word.add(symbol.getEvent());

                List<String> roWord = ListUtils.unmodifiableList(word);

                if (prefixPredicate.evaluate(roWord)) {
                    trace.addLast(new Pair<>(nextState, nextState.getDefinedSymbols().iterator()));

                    if (nextState.isFinalState() && wordPredicate.evaluate(roWord))
                        return word;
                } else {
                    word.removeLast();
                }
            }
        }
    }

    return null;
}

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