java.util.Collection.clear()方法的使用及代码示例

x33g5p2x  于2022-01-16 转载在 其他  
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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

  1. public void setDynamicRecords( Collection<DynamicRecord> records )
  2. {
  3.   this.records.clear();
  4.   this.records.addAll( records );
  5. }

代码示例来源：origin: stanfordnlp/CoreNLP

  1. public void setRoot(IndexedWord word) {
  2.  roots.clear();
  3.  roots.add(word);
  4. }

代码示例来源：origin: google/guava

  1. /** Removes all values for the provided key. */
  2. private void removeValuesForKey(Object key) {
  3.  Collection<V> collection = Maps.safeRemove(map, key);
  4.  if (collection != null) {
  5.   int count = collection.size();
  6.   collection.clear();
  7.   totalSize -= count;
  8.  }
  9. }

代码示例来源：origin: google/guava

  1. boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
  2.  Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
  3.  boolean changed = false;
  4.  while (entryIterator.hasNext()) {
  5.   Entry<K, Collection<V>> entry = entryIterator.next();
  6.   K key = entry.getKey();
  7.   Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
  8.   if (!collection.isEmpty() && predicate.apply(Maps.immutableEntry(key, collection))) {
  9.    if (collection.size() == entry.getValue().size()) {
  10.     entryIterator.remove();
  11.    } else {
  12.     collection.clear();
  13.    }
  14.    changed = true;
  15.   }
  16.  }
  17.  return changed;
  18. }

代码示例来源：origin: google/guava

  1. @CollectionFeature.Require({SUPPORTS_REMOVE, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
  2.  @CollectionSize.Require(SEVERAL)
  3.  public void testClearConcurrentWithIteration() {
  4.   try {
  5.    Iterator<E> iterator = collection.iterator();
  6.    collection.clear();
  7.    iterator.next();
  8.    /*
  9.     * We prefer for iterators to fail immediately on hasNext, but ArrayList
  10.     * and LinkedList will notably return true on hasNext here!
  11.     */
  12.    fail("Expected ConcurrentModificationException");
  13.   } catch (ConcurrentModificationException expected) {
  14.    // success
  15.   }
  16.  }
  17. }

代码示例来源：origin: wildfly/wildfly

  1. public void handleMembershipChange(Collection<Request> requests) {
  2.   Collection<Address> leaving_mbrs=new LinkedHashSet<>(requests.size());
  3.   requests.forEach(r -> {
  4.     if(r.type == Request.SUSPECT)
  5.       suspected_mbrs.add(r.mbr);
  6.     else if(r.type == Request.LEAVE)
  7.       leaving_mbrs.add(r.mbr);
  8.   });
  9.   if(suspected_mbrs.isEmpty() && leaving_mbrs.isEmpty())
  10.     return;
  11.   if(wouldIBeCoordinator(leaving_mbrs)) {
  12.     log.debug("%s: members are %s, coord=%s: I'm the new coordinator", gms.local_addr, gms.members, gms.local_addr);
  13.     gms.becomeCoordinator();
  14.     Collection<Request> leavingOrSuspectedMembers=new LinkedHashSet<>();
  15.     leaving_mbrs.forEach(mbr -> leavingOrSuspectedMembers.add(new Request(Request.LEAVE, mbr)));
  16.     suspected_mbrs.forEach(mbr -> {
  17.       leavingOrSuspectedMembers.add(new Request(Request.SUSPECT, mbr));
  18.       gms.ack_collector.suspect(mbr);
  19.     });
  20.     suspected_mbrs.clear();
  21.     gms.getViewHandler().add(leavingOrSuspectedMembers);
  22.   }
  23. }

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

  1. /**
  2.  * Clear the map.
  3.  * <p>
  4.  * This clears each collection in the map, and so may be slow.
  5.  */
  6. public void clear() {
  7.   // For gc, clear each list in the map
  8.   Set pairs = super.entrySet();
  9.   Iterator pairsIterator = pairs.iterator();
  10.   while (pairsIterator.hasNext()) {
  11.     Map.Entry keyValuePair = (Map.Entry) pairsIterator.next();
  12.     Collection coll = (Collection) keyValuePair.getValue();
  13.     coll.clear();
  14.   }
  15.   super.clear();
  16. }

代码示例来源：origin: google/guava

  1. @CollectionFeature.Require(SUPPORTS_REMOVE)
  2. public void testClear() {
  3.  collection.clear();
  4.  assertTrue("After clear(), a collection should be empty.", collection.isEmpty());
  5.  assertEquals(0, collection.size());
  6.  assertFalse(collection.iterator().hasNext());
  7. }

代码示例来源：origin: Bilibili/DanmakuFlameMaster

  1. public void setItems(Collection<BaseDanmaku> items) {
  2.   if (mDuplicateMergingEnabled && mSortType != ST_BY_LIST) {
  3.     synchronized (this.mLockObject) {
  4.       this.items.clear();
  5.       this.items.addAll(items);
  6.       items = this.items;
  7.     }
  8.   } else {
  9.     this.items = items;
  10.   }
  11.   if (items instanceof List) {
  12.     mSortType = ST_BY_LIST;
  13.   }
  14.   mSize.set(items == null ? 0 : items.size());
  15. }

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

  1. /**
  2.  * Tests {@link Set#equals(Object)}.
  3.  */
  4. public void testSetEquals() {
  5.   resetEmpty();
  6.   assertEquals("Empty sets should be equal", 
  7.          getSet(), getConfirmedSet());
  8.   verify();
  9.   Collection set2 = makeConfirmedCollection();
  10.   set2.add("foo");
  11.   assertTrue("Empty set shouldn't equal nonempty set", 
  12.         !getSet().equals(set2));
  13.   resetFull();
  14.   assertEquals("Full sets should be equal", getSet(), getConfirmedSet());
  15.   verify();
  16.   set2.clear();
  17.   set2.addAll(Arrays.asList(getOtherElements()));
  18.   assertTrue("Sets with different contents shouldn't be equal", 
  19.         !getSet().equals(set2));
  20. }

代码示例来源：origin: google/guava

  1. /**
  2.  * {@inheritDoc}
  3.  *
  4.  * <p>The returned collection is immutable.
  5.  */
  6. @Override
  7. public Collection<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
  8.  Iterator<? extends V> iterator = values.iterator();
  9.  if (!iterator.hasNext()) {
  10.   return removeAll(key);
  11.  }
  12.  // TODO(lowasser): investigate atomic failure?
  13.  Collection<V> collection = getOrCreateCollection(key);
  14.  Collection<V> oldValues = createCollection();
  15.  oldValues.addAll(collection);
  16.  totalSize -= collection.size();
  17.  collection.clear();
  18.  while (iterator.hasNext()) {
  19.   if (collection.add(iterator.next())) {
  20.    totalSize++;
  21.   }
  22.  }
  23.  return unmodifiableCollectionSubclass(oldValues);
  24. }

代码示例来源：origin: google/guava

  1. Collection<V> values = multimap.asMap().entrySet().iterator().next().getValue();
  2. K key = multimap.keySet().iterator().next();
  3. assertCollectionIsUnmodifiable(multimap.get(key), sampleValue);
  4. assertMultimapRemainsUnmodified(multimap, originalEntries);
  5. K presentKey = multimap.keySet().iterator().next();
  6. try {
  7.  multimap.asMap().get(presentKey).remove(sampleValue);
  8.  multimap.asMap().values().iterator().next().remove(sampleValue);
  9.  fail("asMap().values().iterator().next().remove() succeeded on unmodifiable multimap");
  10. } catch (UnsupportedOperationException expected) {
  11.  ((Collection<?>) multimap.asMap().values().toArray()[0]).clear();
  12.  fail("asMap().values().toArray()[0].clear() succeeded on unmodifiable multimap");
  13. } catch (UnsupportedOperationException expected) {

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

  1. /**
  2.  * Factory method to create a transforming collection that will transform
  3.  * existing contents of the specified collection.
  4.  * <p>
  5.  * If there are any elements already in the collection being decorated, they
  6.  * will be transformed by this method.
  7.  * Contrast this with {@link #transformingCollection(Collection, Transformer)}.
  8.  *
  9.  * @param <E> the type of the elements in the collection
  10.  * @param collection  the collection to decorate, must not be null
  11.  * @param transformer  the transformer to use for conversion, must not be null
  12.  * @return a new transformed Collection
  13.  * @throws NullPointerException if collection or transformer is null
  14.  * @since 4.0
  15.  */
  16. public static <E> TransformedCollection<E> transformedCollection(final Collection<E> collection,
  17.     final Transformer<? super E, ? extends E> transformer) {
  18.   final TransformedCollection<E> decorated = new TransformedCollection<>(collection, transformer);
  19.   // null collection & transformer are disallowed by the constructor call above
  20.   if (collection.size() > 0) {
  21.     @SuppressWarnings("unchecked") // collection is of type E
  22.     final E[] values = (E[]) collection.toArray(); // NOPMD - false positive for generics
  23.     collection.clear();
  24.     for (final E value : values) {
  25.       decorated.decorated().add(transformer.transform(value));
  26.     }
  27.   }
  28.   return decorated;
  29. }

代码示例来源：origin: wildfly/wildfly

  1. /**
  2.  * Clear the map.
  3.  * <p>
  4.  * This clears each collection in the map, and so may be slow.
  5.  */
  6. public void clear() {
  7.   // For gc, clear each list in the map
  8.   Set pairs = super.entrySet();
  9.   Iterator pairsIterator = pairs.iterator();
  10.   while (pairsIterator.hasNext()) {
  11.     Map.Entry keyValuePair = (Map.Entry) pairsIterator.next();
  12.     Collection coll = (Collection) keyValuePair.getValue();
  13.     coll.clear();
  14.   }
  15.   super.clear();
  16. }

代码示例来源：origin: google/guava

  1. /**
  2.  * {@inheritDoc}
  3.  *
  4.  * <p>The returned collection is immutable.
  5.  */
  6. @Override
  7. public Collection<V> removeAll(@Nullable Object key) {
  8.  Collection<V> collection = map.remove(key);
  9.  if (collection == null) {
  10.   return createUnmodifiableEmptyCollection();
  11.  }
  12.  Collection<V> output = createCollection();
  13.  output.addAll(collection);
  14.  totalSize -= collection.size();
  15.  collection.clear();
  16.  return unmodifiableCollectionSubclass(output);
  17. }

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

  1. private Collection<SQLException> closeResultSets() {
  2.   Collection<SQLException> result = new LinkedList<>();
  3.   for (ResultSet each : cachedResultSets) {
  4.     try {
  5.       each.close();
  6.     } catch (final SQLException ex) {
  7.       result.add(ex);
  8.     }
  9.   }
  10.   cachedResultSets.clear();
  11.   return result;
  12. }

代码示例来源：origin: prestodb/presto

  1. /** Removes all values for the provided key. */
  2. private void removeValuesForKey(Object key) {
  3.  Collection<V> collection = Maps.safeRemove(map, key);
  4.  if (collection != null) {
  5.   int count = collection.size();
  6.   collection.clear();
  7.   totalSize -= count;
  8.  }
  9. }

代码示例来源：origin: stanfordnlp/CoreNLP

  1. public void setRoots(Collection<IndexedWord> words) {
  2.  roots.clear();
  3.  roots.addAll(words);
  4. }

代码示例来源：origin: google/j2objc

  1. boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
  2.  Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
  3.  boolean changed = false;
  4.  while (entryIterator.hasNext()) {
  5.   Entry<K, Collection<V>> entry = entryIterator.next();
  6.   K key = entry.getKey();
  7.   Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
  8.   if (!collection.isEmpty() && predicate.apply(Maps.immutableEntry(key, collection))) {
  9.    if (collection.size() == entry.getValue().size()) {
  10.     entryIterator.remove();
  11.    } else {
  12.     collection.clear();
  13.    }
  14.    changed = true;
  15.   }
  16.  }
  17.  return changed;
  18. }

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

  1. collection.clear();
  2.   fail("clear should raise UnsupportedOperationException");
  3. } catch (UnsupportedOperationException e) {
  4.   Iterator iterator = collection.iterator();
  5.   iterator.next();
  6.   iterator.remove();
  7.   fail("iterator.remove should raise UnsupportedOperationException");

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