本文整理了Java中java.util.Collection.clear()方法的一些代码示例，展示了Collection.clear()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Collection.clear()方法的具体详情如下：
包路径：java.util.Collection
类名称：Collection
方法名：clear

Collection.clear介绍

[英]Removes all elements from this Collection, leaving it empty (optional).
[中]删除此集合中的所有元素，将其保留为空（可选）。

代码示例

代码示例来源：origin: neo4j/neo4j

public void setDynamicRecords( Collection<DynamicRecord> records )
{
  this.records.clear();
  this.records.addAll( records );
}

代码示例来源：origin: stanfordnlp/CoreNLP

public void setRoot(IndexedWord word) {
 roots.clear();
 roots.add(word);
}

代码示例来源：origin: google/guava

/** Removes all values for the provided key. */
private void removeValuesForKey(Object key) {
 Collection<V> collection = Maps.safeRemove(map, key);
 if (collection != null) {
  int count = collection.size();
  collection.clear();
  totalSize -= count;
 }
}

代码示例来源：origin: google/guava

boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
 Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
 boolean changed = false;
 while (entryIterator.hasNext()) {
  Entry<K, Collection<V>> entry = entryIterator.next();
  K key = entry.getKey();
  Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
  if (!collection.isEmpty() && predicate.apply(Maps.immutableEntry(key, collection))) {
   if (collection.size() == entry.getValue().size()) {
    entryIterator.remove();
   } else {
    collection.clear();
   }
   changed = true;
  }
 }
 return changed;
}

代码示例来源：origin: google/guava

@CollectionFeature.Require({SUPPORTS_REMOVE, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
 @CollectionSize.Require(SEVERAL)
 public void testClearConcurrentWithIteration() {
  try {
   Iterator<E> iterator = collection.iterator();
   collection.clear();
   iterator.next();
   /*
    * We prefer for iterators to fail immediately on hasNext, but ArrayList
    * and LinkedList will notably return true on hasNext here!
    */
   fail("Expected ConcurrentModificationException");
  } catch (ConcurrentModificationException expected) {
   // success
  }
 }
}

代码示例来源：origin: wildfly/wildfly

public void handleMembershipChange(Collection<Request> requests) {
  Collection<Address> leaving_mbrs=new LinkedHashSet<>(requests.size());
  requests.forEach(r -> {
    if(r.type == Request.SUSPECT)
      suspected_mbrs.add(r.mbr);
    else if(r.type == Request.LEAVE)
      leaving_mbrs.add(r.mbr);
  });
  if(suspected_mbrs.isEmpty() && leaving_mbrs.isEmpty())
    return;
  if(wouldIBeCoordinator(leaving_mbrs)) {
    log.debug("%s: members are %s, coord=%s: I'm the new coordinator", gms.local_addr, gms.members, gms.local_addr);
    gms.becomeCoordinator();
    Collection<Request> leavingOrSuspectedMembers=new LinkedHashSet<>();
    leaving_mbrs.forEach(mbr -> leavingOrSuspectedMembers.add(new Request(Request.LEAVE, mbr)));
    suspected_mbrs.forEach(mbr -> {
      leavingOrSuspectedMembers.add(new Request(Request.SUSPECT, mbr));
      gms.ack_collector.suspect(mbr);
    });
    suspected_mbrs.clear();
    gms.getViewHandler().add(leavingOrSuspectedMembers);
  }
}

代码示例来源：origin: commons-collections/commons-collections

/**
 * Clear the map.
 * <p>
 * This clears each collection in the map, and so may be slow.
 */
public void clear() {
  // For gc, clear each list in the map
  Set pairs = super.entrySet();
  Iterator pairsIterator = pairs.iterator();
  while (pairsIterator.hasNext()) {
    Map.Entry keyValuePair = (Map.Entry) pairsIterator.next();
    Collection coll = (Collection) keyValuePair.getValue();
    coll.clear();
  }
  super.clear();
}

代码示例来源：origin: google/guava

@CollectionFeature.Require(SUPPORTS_REMOVE)
public void testClear() {
 collection.clear();
 assertTrue("After clear(), a collection should be empty.", collection.isEmpty());
 assertEquals(0, collection.size());
 assertFalse(collection.iterator().hasNext());
}

代码示例来源：origin: Bilibili/DanmakuFlameMaster

public void setItems(Collection<BaseDanmaku> items) {
  if (mDuplicateMergingEnabled && mSortType != ST_BY_LIST) {
    synchronized (this.mLockObject) {
      this.items.clear();
      this.items.addAll(items);
      items = this.items;
    }
  } else {
    this.items = items;
  }
  if (items instanceof List) {
    mSortType = ST_BY_LIST;
  }
  mSize.set(items == null ? 0 : items.size());
}

代码示例来源：origin: commons-collections/commons-collections

/**
 * Tests {@link Set#equals(Object)}.
 */
public void testSetEquals() {
  resetEmpty();
  assertEquals("Empty sets should be equal", 
         getSet(), getConfirmedSet());
  verify();
  Collection set2 = makeConfirmedCollection();
  set2.add("foo");
  assertTrue("Empty set shouldn't equal nonempty set", 
        !getSet().equals(set2));
  resetFull();
  assertEquals("Full sets should be equal", getSet(), getConfirmedSet());
  verify();
  set2.clear();
  set2.addAll(Arrays.asList(getOtherElements()));
  assertTrue("Sets with different contents shouldn't be equal", 
        !getSet().equals(set2));
}

代码示例来源：origin: google/guava

/**
 * {@inheritDoc}
 *
 * <p>The returned collection is immutable.
 */
@Override
public Collection<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
 Iterator<? extends V> iterator = values.iterator();
 if (!iterator.hasNext()) {
  return removeAll(key);
 }
 // TODO(lowasser): investigate atomic failure?
 Collection<V> collection = getOrCreateCollection(key);
 Collection<V> oldValues = createCollection();
 oldValues.addAll(collection);
 totalSize -= collection.size();
 collection.clear();
 while (iterator.hasNext()) {
  if (collection.add(iterator.next())) {
   totalSize++;
  }
 }
 return unmodifiableCollectionSubclass(oldValues);
}

代码示例来源：origin: google/guava

Collection<V> values = multimap.asMap().entrySet().iterator().next().getValue();
K key = multimap.keySet().iterator().next();
assertCollectionIsUnmodifiable(multimap.get(key), sampleValue);
assertMultimapRemainsUnmodified(multimap, originalEntries);
K presentKey = multimap.keySet().iterator().next();
try {
 multimap.asMap().get(presentKey).remove(sampleValue);
 multimap.asMap().values().iterator().next().remove(sampleValue);
 fail("asMap().values().iterator().next().remove() succeeded on unmodifiable multimap");
} catch (UnsupportedOperationException expected) {
 ((Collection<?>) multimap.asMap().values().toArray()[0]).clear();
 fail("asMap().values().toArray()[0].clear() succeeded on unmodifiable multimap");
} catch (UnsupportedOperationException expected) {

代码示例来源：origin: org.apache.commons/commons-collections4

/**
 * Factory method to create a transforming collection that will transform
 * existing contents of the specified collection.
 * <p>
 * If there are any elements already in the collection being decorated, they
 * will be transformed by this method.
 * Contrast this with {@link #transformingCollection(Collection, Transformer)}.
 *
 * @param <E> the type of the elements in the collection
 * @param collection  the collection to decorate, must not be null
 * @param transformer  the transformer to use for conversion, must not be null
 * @return a new transformed Collection
 * @throws NullPointerException if collection or transformer is null
 * @since 4.0
 */
public static <E> TransformedCollection<E> transformedCollection(final Collection<E> collection,
    final Transformer<? super E, ? extends E> transformer) {
  final TransformedCollection<E> decorated = new TransformedCollection<>(collection, transformer);
  // null collection & transformer are disallowed by the constructor call above
  if (collection.size() > 0) {
    @SuppressWarnings("unchecked") // collection is of type E
    final E[] values = (E[]) collection.toArray(); // NOPMD - false positive for generics
    collection.clear();
    for (final E value : values) {
      decorated.decorated().add(transformer.transform(value));
    }
  }
  return decorated;
}

代码示例来源：origin: wildfly/wildfly

/**
 * Clear the map.
 * <p>
 * This clears each collection in the map, and so may be slow.
 */
public void clear() {
  // For gc, clear each list in the map
  Set pairs = super.entrySet();
  Iterator pairsIterator = pairs.iterator();
  while (pairsIterator.hasNext()) {
    Map.Entry keyValuePair = (Map.Entry) pairsIterator.next();
    Collection coll = (Collection) keyValuePair.getValue();
    coll.clear();
  }
  super.clear();
}

代码示例来源：origin: google/guava

/**
 * {@inheritDoc}
 *
 * <p>The returned collection is immutable.
 */
@Override
public Collection<V> removeAll(@Nullable Object key) {
 Collection<V> collection = map.remove(key);
 if (collection == null) {
  return createUnmodifiableEmptyCollection();
 }
 Collection<V> output = createCollection();
 output.addAll(collection);
 totalSize -= collection.size();
 collection.clear();
 return unmodifiableCollectionSubclass(output);
}

代码示例来源：origin: apache/incubator-shardingsphere

private Collection<SQLException> closeResultSets() {
  Collection<SQLException> result = new LinkedList<>();
  for (ResultSet each : cachedResultSets) {
    try {
      each.close();
    } catch (final SQLException ex) {
      result.add(ex);
    }
  }
  cachedResultSets.clear();
  return result;
}

代码示例来源：origin: prestodb/presto

/** Removes all values for the provided key. */
private void removeValuesForKey(Object key) {
 Collection<V> collection = Maps.safeRemove(map, key);
 if (collection != null) {
  int count = collection.size();
  collection.clear();
  totalSize -= count;
 }
}

代码示例来源：origin: stanfordnlp/CoreNLP

public void setRoots(Collection<IndexedWord> words) {
 roots.clear();
 roots.addAll(words);
}

代码示例来源：origin: google/j2objc

boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
 Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
 boolean changed = false;
 while (entryIterator.hasNext()) {
  Entry<K, Collection<V>> entry = entryIterator.next();
  K key = entry.getKey();
  Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
  if (!collection.isEmpty() && predicate.apply(Maps.immutableEntry(key, collection))) {
   if (collection.size() == entry.getValue().size()) {
    entryIterator.remove();
   } else {
    collection.clear();
   }
   changed = true;
  }
 }
 return changed;
}

代码示例来源：origin: commons-collections/commons-collections

collection.clear();
  fail("clear should raise UnsupportedOperationException");
} catch (UnsupportedOperationException e) {
  Iterator iterator = collection.iterator();
  iterator.next();
  iterator.remove();
  fail("iterator.remove should raise UnsupportedOperationException");