本文整理了Java中java.util.Collections.emptyMap()
方法的一些代码示例,展示了Collections.emptyMap()
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。Collections.emptyMap()
方法的具体详情如下:
包路径:java.util.Collections
类名称:Collections
方法名:emptyMap
[英]Returns a type-safe empty, immutable Map.
[中]返回类型安全的空、不可变映射。
代码示例来源:origin: square/okhttp
/** Returns an immutable copy of {@code map}. */
public static <K, V> Map<K, V> immutableMap(Map<K, V> map) {
return map.isEmpty()
? Collections.emptyMap()
: Collections.unmodifiableMap(new LinkedHashMap<>(map));
}
代码示例来源:origin: skylot/jadx
public static Map<String, String> newConstStringMap(String... parameters) {
int len = parameters.length;
if (len == 0) {
return Collections.emptyMap();
}
Map<String, String> result = new HashMap<>(len / 2);
for (int i = 0; i < len; i += 2) {
result.put(parameters[i], parameters[i + 1]);
}
return Collections.unmodifiableMap(result);
}
}
代码示例来源:origin: spring-projects/spring-framework
@Override
@SuppressWarnings("unchecked")
protected Object resolveNamedValue(String name, MethodParameter parameter, ServerWebExchange exchange) {
String attributeName = HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE;
return exchange.getAttributeOrDefault(attributeName, Collections.emptyMap()).get(name);
}
代码示例来源:origin: Graylog2/graylog2-server
private Map<String, String> prefixElements(final String prefix, final Map<String, String> elements) {
if (elements == null || elements.isEmpty()) {
return Collections.emptyMap();
}
final Map<String, String> prefixedMap = new HashMap<>(elements.size());
for (Map.Entry<String, String> entry : elements.entrySet()) {
prefixedMap.put(prefix.trim() + "_" + entry.getKey(), entry.getValue());
}
return prefixedMap;
}
}
代码示例来源:origin: mpusher/mpush
@Override
public <T> Map<String, T> hgetAll(String key, Class<T> clazz) {
Map<String, Object> m = (Map) cache.get(key);
if (m == null || m.isEmpty()) return Collections.emptyMap();
Map<String, T> result = new HashMap<>();
for (Map.Entry<String, Object> o : m.entrySet()) {
result.put(o.getKey(), Jsons.fromJson(String.valueOf(o.getValue()), clazz));
}
return result;
}
代码示例来源:origin: apache/kafka
@Test
public void testSaslLoginRefreshDefaults() {
Map<String, Object> vals = new ConfigDef().withClientSaslSupport().parse(Collections.emptyMap());
assertEquals(SaslConfigs.DEFAULT_LOGIN_REFRESH_WINDOW_FACTOR,
vals.get(SaslConfigs.SASL_LOGIN_REFRESH_WINDOW_FACTOR));
assertEquals(SaslConfigs.DEFAULT_LOGIN_REFRESH_WINDOW_JITTER,
vals.get(SaslConfigs.SASL_LOGIN_REFRESH_WINDOW_JITTER));
assertEquals(SaslConfigs.DEFAULT_LOGIN_REFRESH_MIN_PERIOD_SECONDS,
vals.get(SaslConfigs.SASL_LOGIN_REFRESH_MIN_PERIOD_SECONDS));
assertEquals(SaslConfigs.DEFAULT_LOGIN_REFRESH_BUFFER_SECONDS,
vals.get(SaslConfigs.SASL_LOGIN_REFRESH_BUFFER_SECONDS));
}
代码示例来源:origin: Activiti/Activiti
public Map<String, Object> getTransientVariablesLocal() {
if (transientVariabes != null) {
Map<String, Object> variables = new HashMap<String, Object>();
for (String variableName : transientVariabes.keySet()) {
variables.put(variableName, transientVariabes.get(variableName).getValue());
}
return variables;
} else {
return Collections.emptyMap();
}
}
代码示例来源:origin: spring-projects/spring-framework
@Test
@SuppressWarnings("unchecked")
public void resolveArgumentNoUriVars() throws Exception {
Map<String, String> map = (Map<String, String>) resolver.resolveArgument(paramMap, mavContainer, webRequest, null);
assertEquals(Collections.emptyMap(), map);
}
代码示例来源:origin: spring-projects/spring-security
@Test
public void convertWhenIssuerIsOfTypeURLThenConvertsToString() throws Exception {
MappedJwtClaimSetConverter converter = MappedJwtClaimSetConverter
.withDefaults(Collections.emptyMap());
Map<String, Object> issuer = Collections.singletonMap(JwtClaimNames.ISS, new URL("https://issuer"));
Map<String, Object> target = converter.convert(issuer);
assertThat(target.get(JwtClaimNames.ISS)).isEqualTo("https://issuer");
}
代码示例来源:origin: Netflix/eureka
private static Map<String, String> headersOf(Response response) {
MultivaluedMap<String, String> jerseyHeaders = response.getStringHeaders();
if (jerseyHeaders == null || jerseyHeaders.isEmpty()) {
return Collections.emptyMap();
}
Map<String, String> headers = new HashMap<>();
for (Entry<String, List<String>> entry : jerseyHeaders.entrySet()) {
if (!entry.getValue().isEmpty()) {
headers.put(entry.getKey(), entry.getValue().get(0));
}
}
return headers;
}
}
代码示例来源:origin: SonarSource/sonarqube
@Override
public ActiveRule find(RuleKey ruleKey) {
return activeRulesByRepositoryAndKey.getOrDefault(ruleKey.repository(), Collections.emptyMap())
.get(ruleKey.rule());
}
代码示例来源:origin: apache/storm
/**
* Get a map of version to worker log writer from the conf Config.SUPERVISOR_WORKER_VERSION_LOGWRITER_MAP
*
* @param conf what to read it out of
* @return the map
*/
public static NavigableMap<SimpleVersion, String> getConfiguredWorkerLogWriterVersions(Map<String, Object> conf) {
TreeMap<SimpleVersion, String> ret = new TreeMap<>();
Map<String, String> fromConf =
(Map<String, String>) conf.getOrDefault(Config.SUPERVISOR_WORKER_VERSION_LOGWRITER_MAP, Collections.emptyMap());
for (Map.Entry<String, String> entry : fromConf.entrySet()) {
ret.put(new SimpleVersion(entry.getKey()), entry.getValue());
}
ret.put(VersionInfo.OUR_VERSION, "org.apache.storm.LogWriter");
return ret;
}
代码示例来源:origin: spring-projects/spring-framework
@Test(expected = InvalidDataAccessApiUsageException.class)
public void buildValueArrayWithMissingParameterValue() {
String sql = "select count(0) from foo where id = :id";
NamedParameterUtils.buildValueArray(sql, Collections.<String, Object>emptyMap());
}
代码示例来源:origin: square/okhttp
@Override public List<Cookie> loadForRequest(HttpUrl url) {
// The RI passes all headers. We don't have 'em, so we don't pass 'em!
Map<String, List<String>> headers = Collections.emptyMap();
Map<String, List<String>> cookieHeaders;
try {
cookieHeaders = cookieHandler.get(url.uri(), headers);
} catch (IOException e) {
Platform.get().log(WARN, "Loading cookies failed for " + url.resolve("/..."), e);
return Collections.emptyList();
}
List<Cookie> cookies = null;
for (Map.Entry<String, List<String>> entry : cookieHeaders.entrySet()) {
String key = entry.getKey();
if (("Cookie".equalsIgnoreCase(key) || "Cookie2".equalsIgnoreCase(key))
&& !entry.getValue().isEmpty()) {
for (String header : entry.getValue()) {
if (cookies == null) cookies = new ArrayList<>();
cookies.addAll(decodeHeaderAsJavaNetCookies(url, header));
}
}
}
return cookies != null
? Collections.unmodifiableList(cookies)
: Collections.emptyList();
}
代码示例来源:origin: spring-projects/spring-framework
/**
* Create a WebSocketExtension with the given name and parameters.
* @param name the name of the extension
* @param parameters the parameters
*/
public WebSocketExtension(String name, @Nullable Map<String, String> parameters) {
Assert.hasLength(name, "Extension name must not be empty");
this.name = name;
if (!CollectionUtils.isEmpty(parameters)) {
Map<String, String> map = new LinkedCaseInsensitiveMap<>(parameters.size(), Locale.ENGLISH);
map.putAll(parameters);
this.parameters = Collections.unmodifiableMap(map);
}
else {
this.parameters = Collections.emptyMap();
}
}
代码示例来源:origin: skylot/jadx
public Map<CodePosition, JavaNode> getUsageMap() {
Map<CodePosition, Object> map = getCodeAnnotations();
if (map.isEmpty() || decompiler == null) {
return Collections.emptyMap();
}
Map<CodePosition, JavaNode> resultMap = new HashMap<>(map.size());
for (Map.Entry<CodePosition, Object> entry : map.entrySet()) {
CodePosition codePosition = entry.getKey();
Object obj = entry.getValue();
if (obj instanceof LineAttrNode) {
JavaNode node = convertNode(obj);
if (node != null) {
resultMap.put(codePosition, node);
}
}
}
return resultMap;
}
代码示例来源:origin: prestodb/presto
@Override
public Optional<Map<DecoderColumnHandle, FieldValueProvider>> decodeRow(byte[] data, Map<String, String> dataMap)
{
if (dataMap == null) {
return Optional.of(emptyMap());
}
Map<DecoderColumnHandle, FieldValueProvider> decodedRow = new HashMap<>();
for (Map.Entry<DecoderColumnHandle, RedisFieldDecoder<String>> entry : fieldDecoders.entrySet()) {
DecoderColumnHandle columnHandle = entry.getKey();
String mapping = columnHandle.getMapping();
checkState(mapping != null, "No mapping for column handle %s!", columnHandle);
String valueField = dataMap.get(mapping);
RedisFieldDecoder<String> decoder = entry.getValue();
decodedRow.put(columnHandle, decoder.decode(valueField, columnHandle));
}
return Optional.of(decodedRow);
}
}
代码示例来源:origin: apache/storm
@Test
public void getNimbusAutoCredPluginTest() {
Map<String, Object> map = new HashMap<>();
map.put(Config.NIMBUS_AUTO_CRED_PLUGINS,
Arrays.asList(new String[]{ "org.apache.storm.security.auth.AuthUtilsTestMock" }));
Assert.assertTrue(ClientAuthUtils.getNimbusAutoCredPlugins(Collections.emptyMap()).isEmpty());
Assert.assertEquals(ClientAuthUtils.getNimbusAutoCredPlugins(map).size(), 1);
}
代码示例来源:origin: spring-projects/spring-framework
return Collections.emptyMap();
Map<String, List<String>> map = attributeAliasesCache.get(annotationType);
if (map != null) {
return map;
List<String> aliasNames = getAttributeAliasNames(attribute);
if (!aliasNames.isEmpty()) {
map.put(attribute.getName(), aliasNames);
attributeAliasesCache.put(annotationType, map);
return map;
代码示例来源:origin: redisson/redisson
/**
* {@inheritDoc}
*/
public Generic get(int index) {
// Avoid resolution of interface bound type unless a type annotation can be possibly resolved.
Map<String, List<AnnotationToken>> annotationTokens = !this.annotationTokens.containsKey(index) && !this.annotationTokens.containsKey(index + 1)
? Collections.<String, List<AnnotationToken>>emptyMap()
: this.annotationTokens.get(index + (boundTypeTokens.get(0).isPrimaryBound(typePool) ? 0 : 1));
return boundTypeTokens.get(index).toGenericType(typePool,
typeVariableSource,
EMPTY_TYPE_PATH,
annotationTokens == null
? Collections.<String, List<AnnotationToken>>emptyMap()
: annotationTokens);
}
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