本文整理了Java中java.util.Map.size()方法的一些代码示例，展示了Map.size()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。Map.size()方法的具体详情如下：
包路径：java.util.Map
类名称：Map
方法名：size

Map.size介绍

[英]Returns the number of mappings in this Map.
[中]返回此映射中的映射数。

代码示例

代码示例来源：origin: google/guava

/**
 * Stores the contents of a map in an output stream, as part of serialization. It does not support
 * concurrent maps whose content may change while the method is running.
 *
 * <p>The serialized output consists of the number of entries, first key, first value, second key,
 * second value, and so on.
 */
static <K, V> void writeMap(Map<K, V> map, ObjectOutputStream stream) throws IOException {
 stream.writeInt(map.size());
 for (Map.Entry<K, V> entry : map.entrySet()) {
  stream.writeObject(entry.getKey());
  stream.writeObject(entry.getValue());
 }
}

代码示例来源：origin: bumptech/glide

private Map<String, List<LazyHeaderFactory>> copyHeaders() {
 Map<String, List<LazyHeaderFactory>> result = new HashMap<>(headers.size());
 for (Map.Entry<String, List<LazyHeaderFactory>> entry : headers.entrySet()) {
  @SuppressWarnings("PMD.AvoidInstantiatingObjectsInLoops")
  List<LazyHeaderFactory> valueCopy = new ArrayList<>(entry.getValue());
  result.put(entry.getKey(), valueCopy);
 }
 return result;
}

代码示例来源：origin: hankcs/HanLP

@Override
public int idOf(String string)
{
  Integer id = featureIdMap.get(string);
  if (id == null)
  {
    id = featureIdMap.size();
    featureIdMap.put(string, id);
  }
  return id;
}

代码示例来源：origin: google/guava

final void assertNonNullValues(Object... expectedValues) {
 assertEquals(expectedValues.length, arguments.size());
 for (int i = 0; i < expectedValues.length; i++) {
  assertEquals("Default value for parameter #" + i, expectedValues[i], arguments.get(i));
 }
}

代码示例来源：origin: spring-projects/spring-framework

private StompHeaders(Map<String, List<String>> headers, boolean readOnly) {
  Assert.notNull(headers, "'headers' must not be null");
  if (readOnly) {
    Map<String, List<String>> map = new LinkedMultiValueMap<>(headers.size());
    headers.forEach((key, value) -> map.put(key, Collections.unmodifiableList(value)));
    this.headers = Collections.unmodifiableMap(map);
  }
  else {
    this.headers = headers;
  }
}

代码示例来源：origin: google/guava

static <N, V> DirectedGraphConnections<N, V> ofImmutable(
  Set<N> predecessors, Map<N, V> successorValues) {
 Map<N, Object> adjacentNodeValues = new HashMap<>();
 adjacentNodeValues.putAll(successorValues);
 for (N predecessor : predecessors) {
  Object value = adjacentNodeValues.put(predecessor, PRED);
  if (value != null) {
   adjacentNodeValues.put(predecessor, new PredAndSucc(value));
  }
 }
 return new DirectedGraphConnections<>(
   ImmutableMap.copyOf(adjacentNodeValues), predecessors.size(), successorValues.size());
}

代码示例来源：origin: hankcs/HanLP

public int add(String tag)
  {
//        assertUnlock();
    Integer id = stringIdMap.get(tag);
    if (id == null)
    {
      id = stringIdMap.size();
      stringIdMap.put(tag, id);
      idStringMap.add(tag);
    }

    return id;
  }

代码示例来源：origin: spring-projects/spring-framework

private Map<String, Class<?>> toClassMap(Map<String, ?> map) throws ClassNotFoundException {
  Map<String, Class<?>> result = new LinkedHashMap<>(map.size());
  for (Map.Entry<String, ?> entry : map.entrySet()) {
    String key = entry.getKey();
    Object value = entry.getValue();
    Class<?> type;
    if (value instanceof Class) {
      type = (Class<?>) value;
    }
    else if (value instanceof String) {
      String className = (String) value;
      type = ClassUtils.forName(className, this.beanClassLoader);
    }
    else {
      throw new IllegalArgumentException("Unknown value [" + value + "] - expected String or Class");
    }
    result.put(key, type);
  }
  return result;
}

代码示例来源：origin: ReactiveX/RxJava

@Test
public void testGroupByWithElementSelector() {
  Observable<String> source = Observable.just("one", "two", "three", "four", "five", "six");
  Observable<GroupedObservable<Integer, Integer>> grouped = source.groupBy(length, length);
  Map<Integer, Collection<Integer>> map = toMap(grouped);
  assertEquals(3, map.size());
  assertArrayEquals(Arrays.asList(3, 3, 3).toArray(), map.get(3).toArray());
  assertArrayEquals(Arrays.asList(4, 4).toArray(), map.get(4).toArray());
  assertArrayEquals(Arrays.asList(5).toArray(), map.get(5).toArray());
}

代码示例来源：origin: jenkinsci/jenkins

private PackedMap(Map<? extends K,? extends V> src) {
  kvpairs = new Object[src.size()*2];
  int i=0;
  for (Entry<? extends K, ? extends V> e : src.entrySet()) {
    kvpairs[i++] = e.getKey();
    kvpairs[i++] = e.getValue();
  }
}

代码示例来源：origin: spring-projects/spring-framework

/**
 * Copy constructor which allows for ignoring certain entries.
 * Used for serialization without non-serializable entries.
 * @param original the MessageHeaders to copy
 * @param keysToIgnore the keys of the entries to ignore
 */
private MessageHeaders(MessageHeaders original, Set<String> keysToIgnore) {
  this.headers = new HashMap<>(original.headers.size());
  original.headers.forEach((key, value) -> {
    if (!keysToIgnore.contains(key)) {
      this.headers.put(key, value);
    }
  });
}

代码示例来源：origin: hankcs/HanLP

public int addCategory(String category)
{
  Integer id = categoryId.get(category);
  if (id == null)
  {
    id = categoryId.size();
    categoryId.put(category, id);
    assert idCategory.size() == id;
    idCategory.add(category);
  }
  return id;
}

代码示例来源：origin: apache/kafka

private static Map<TopicPartition, Integer> createPartitionSizes(Map<TopicPartition, MemoryRecords> partitionRecords) {
  Map<TopicPartition, Integer> result = new HashMap<>(partitionRecords.size());
  for (Map.Entry<TopicPartition, MemoryRecords> entry : partitionRecords.entrySet())
    result.put(entry.getKey(), entry.getValue().sizeInBytes());
  return result;
}

代码示例来源：origin: ReactiveX/RxJava

@Test
public void testGroupByWithElementSelector2() {
  Observable<String> source = Observable.just("one", "two", "three", "four", "five", "six");
  Observable<GroupedObservable<Integer, Integer>> grouped = source.groupBy(length, length);
  Map<Integer, Collection<Integer>> map = toMap(grouped);
  assertEquals(3, map.size());
  assertArrayEquals(Arrays.asList(3, 3, 3).toArray(), map.get(3).toArray());
  assertArrayEquals(Arrays.asList(4, 4).toArray(), map.get(4).toArray());
  assertArrayEquals(Arrays.asList(5).toArray(), map.get(5).toArray());
}

代码示例来源：origin: jenkinsci/jenkins

private String[] toAttributeList(Map<String, String> attributes) {
  String[] r = new String[attributes.size()*2];
  int i=0;
  for (Entry<String, String> e : attributes.entrySet()) {
    r[i++] = e.getKey();
    r[i++] = e.getValue();
  }
  return r;
}

代码示例来源：origin: spring-projects/spring-framework

/**
 * For each element in the managed map, resolve reference if necessary.
 */
private Map<?, ?> resolveManagedMap(Object argName, Map<?, ?> mm) {
  Map<Object, Object> resolved = new LinkedHashMap<>(mm.size());
  mm.forEach((key, value) -> {
    Object resolvedKey = resolveValueIfNecessary(argName, key);
    Object resolvedValue = resolveValueIfNecessary(new KeyedArgName(argName, key), value);
    resolved.put(resolvedKey, resolvedValue);
  });
  return resolved;
}

代码示例来源：origin: alibaba/druid

public WallSqlTableStat getTableStat(String tableName) {
  if (tableStats == null) {
    tableStats = new HashMap<String, WallSqlTableStat>(2);
  }
  String lowerCaseName = tableName.toLowerCase();
  WallSqlTableStat stat = tableStats.get(lowerCaseName);
  if (stat == null) {
    if (tableStats.size() > 100) {
      return null;
    }
    stat = new WallSqlTableStat();
    tableStats.put(tableName, stat);
  }
  return stat;
}

代码示例来源：origin: apache/kafka

private Map<String, Object> unprefixed(Map<String, Object> parsedConfig) {
  final Map<String, Object> unprefixedParsedConfig = new HashMap<>(parsedConfig.size());
  for (Map.Entry<String, Object> e : parsedConfig.entrySet()) {
    if (e.getKey().startsWith(keyPrefix)) {
      unprefixedParsedConfig.put(unprefixed(e.getKey()), e.getValue());
    }
  }
  return unprefixedParsedConfig;
}

代码示例来源：origin: ReactiveX/RxJava

@Test
public void testGroupBy() {
  Observable<String> source = Observable.just("one", "two", "three", "four", "five", "six");
  Observable<GroupedObservable<Integer, String>> grouped = source.groupBy(length);
  Map<Integer, Collection<String>> map = toMap(grouped);
  assertEquals(3, map.size());
  assertArrayEquals(Arrays.asList("one", "two", "six").toArray(), map.get(3).toArray());
  assertArrayEquals(Arrays.asList("four", "five").toArray(), map.get(4).toArray());
  assertArrayEquals(Arrays.asList("three").toArray(), map.get(5).toArray());
}

代码示例来源：origin: jenkinsci/jenkins

public String[] getEnv() {
  Map<String,String> envs = System.getenv();
  String[] envp = new String[envs.size()];
  
  int i = 0;
  for (Map.Entry<String,String> e : envs.entrySet()) {
    envp[i++] = e.getKey()+'+'+e.getValue();
  }
  return envp;
}