下面列出了怎么用com.google.common.collect.Maps.EntryTransformer的API类实例代码及写法，或者点击链接到github查看源代码。
private Iterable<Group> toGroups(final boolean preserveNumbers, final Collection<Relationship> nonIsARelationshipFragments) {
final Map<Integer, Collection<Relationship>> relationshipsByGroupId = Multimaps.index(nonIsARelationshipFragments, Relationship::getGroup).asMap();
final Collection<Collection<Group>> groups = Maps.transformEntries(relationshipsByGroupId,
(EntryTransformer<Integer, Collection<Relationship>, Collection<Group>>) (key, values) -> {
final Iterable<UnionGroup> unionGroups = toUnionGroups(preserveNumbers, values);
final Set<UnionGroup> disjointUnionGroups = getDisjointComparables(unionGroups);
if (key == 0) {
// Relationships in group 0 form separate groups
return ImmutableList.copyOf(toZeroGroups(disjointUnionGroups));
} else {
// Other group numbers produce a single group from all fragments
return ImmutableList.of(toNonZeroGroup(preserveNumbers, key, disjointUnionGroups));
}
}).values();
return Iterables.concat(groups);
}
private Iterable<UnionGroup> toUnionGroups(final boolean preserveNumbers, final Collection<Relationship> values) {
final Map<Integer, Collection<Relationship>> relationshipsByUnionGroupId = Multimaps.index(values, Relationship::getUnionGroup).asMap();
final Collection<Collection<UnionGroup>> unionGroups = Maps.transformEntries(relationshipsByUnionGroupId,
(EntryTransformer<Integer, Collection<Relationship>, Collection<UnionGroup>>) (key, values1) -> {
if (key == 0) {
// Relationships in union group 0 form separate union groups
return ImmutableList.copyOf(toZeroUnionGroups(values1));
} else {
// Other group numbers produce a single union group from all fragments
return ImmutableList.of(toNonZeroUnionGroup(preserveNumbers, key, values1));
}
}).values();
return Iterables.concat(unionGroups);
}
@Override
public Map<Integer, IPartitionPosition> getPartitionPositions() {
return Maps.transformEntries(partitionOffsetMap, new EntryTransformer<Integer, Long, IPartitionPosition>() {
@Override
public IPartitionPosition transformEntry(@Nullable Integer key, @Nullable Long value) {
return new KafkaPartitionPosition(key, value);
}
});
}
@Override
Map<K, Collection<V2>> createAsMap() {
return Maps.transformEntries(fromMultimap.asMap(), new EntryTransformer<K, Collection<V1>, Collection<V2>>() {
@Override
public Collection<V2> transformEntry(K key, Collection<V1> value) {
return transform(key, value);
}
});
}
@Override
Map<K, Collection<V2>> createAsMap() {
return Maps.transformEntries(fromMultimap.asMap(), new EntryTransformer<K, Collection<V1>, Collection<V2>>() {
@Override
public Collection<V2> transformEntry(K key, Collection<V1> value) {
return transform(key, value);
}
});
}
@Override
Map<K, Collection<V2>> createAsMap() {
return Maps.transformEntries(fromMultimap.asMap(), new EntryTransformer<K, Collection<V1>, Collection<V2>>() {
@Override
public Collection<V2> transformEntry(K key, Collection<V1> value) {
return transform(key, value);
}
});
}
@Override
Map<K, Collection<V2>> createAsMap() {
return Maps.transformEntries(fromMultimap.asMap(), new EntryTransformer<K, Collection<V1>, Collection<V2>>() {
@Override
public Collection<V2> transformEntry(K key, Collection<V1> value) {
return transform(key, value);
}
});
}
@Override
Map<K, Collection<V2>> createAsMap() {
return Maps.transformEntries(
fromMultimap.asMap(),
new EntryTransformer<K, Collection<V1>, Collection<V2>>() {
@Override
public Collection<V2> transformEntry(K key, Collection<V1> value) {
return transform(key, value);
}
});
}
@Override
protected RequestRouter createRequestRouter(final Registry registry, final GlobalConfiguration globalConfiguration) {
final Dispatcher dispatcher = createDispatcher(globalConfiguration.getDispatcherClass());
return new RequestRouter(registry, globalConfiguration, dispatcher)
{
@Override
public void processPollRequest(final Reader reader, final Writer writer, final String pathInfo)
throws IOException
{
new PollRequestProcessor(registry, dispatcher, globalConfiguration)
{
@Override
// HACK: we determine parameters from request not by reading request content as request content could had
// been already read exactly for getting the params, case when request content is already empty
protected Object[] getParameters()
{
if (reader instanceof RequestBoundReader) {
ServletRequest request = ((RequestBoundReader) reader).getRequest();
Map<String, String[]> parameterMap = request.getParameterMap();
Map<String, String> parameters = Maps.newHashMap();
if (parameterMap != null) {
parameters = Maps.transformEntries(parameterMap, new EntryTransformer<String, String[], String>()
{
@Override
public String transformEntry(@Nullable final String key, @Nullable final String[] values) {
return values == null || values.length == 0 ? null : values[0];
}
});
}
return new Object[]{parameters};
}
return super.getParameters();
}
}.process(reader, writer, pathInfo);
}
};
}
/**
* @param brokers in multiple clusters, keyed by cluster id
* @param topic
* @return Get the partition metadata list for the specific topic via the brokers
* null if topic is not found
*/
public static Map<String, List<PartitionMetadata>> getPartitionsForTopic(SetMultimap<String, String> brokers, final String topic)
{
return Maps.transformEntries(brokers.asMap(), new EntryTransformer<String, Collection<String>, List<PartitionMetadata>>()
{
@Override
public List<PartitionMetadata> transformEntry(String key, Collection<String> bs)
{
return getPartitionsForTopic(new HashSet<String>(bs), topic);
}
});
}
TransformedEntriesMultimap(
Multimap<K, V1> fromMultimap,
final EntryTransformer<? super K, ? super V1, V2> transformer) {
this.fromMultimap = checkNotNull(fromMultimap);
this.transformer = checkNotNull(transformer);
}
TransformedEntriesListMultimap(ListMultimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
super(fromMultimap, transformer);
}
TransformedEntriesMultimap(
Multimap<K, V1> fromMultimap,
final EntryTransformer<? super K, ? super V1, V2> transformer) {
this.fromMultimap = checkNotNull(fromMultimap);
this.transformer = checkNotNull(transformer);
}
TransformedEntriesListMultimap(ListMultimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
super(fromMultimap, transformer);
}
TransformedEntriesMultimap(
Multimap<K, V1> fromMultimap,
final EntryTransformer<? super K, ? super V1, V2> transformer) {
this.fromMultimap = checkNotNull(fromMultimap);
this.transformer = checkNotNull(transformer);
}
TransformedEntriesListMultimap(ListMultimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
super(fromMultimap, transformer);
}
TransformedEntriesMultimap(
Multimap<K, V1> fromMultimap,
final EntryTransformer<? super K, ? super V1, V2> transformer) {
this.fromMultimap = checkNotNull(fromMultimap);
this.transformer = checkNotNull(transformer);
}
TransformedEntriesListMultimap(ListMultimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
super(fromMultimap, transformer);
}
TransformedEntriesMultimap(
Multimap<K, V1> fromMultimap,
final EntryTransformer<? super K, ? super V1, V2> transformer) {
this.fromMultimap = checkNotNull(fromMultimap);
this.transformer = checkNotNull(transformer);
}
TransformedEntriesListMultimap(
ListMultimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
super(fromMultimap, transformer);
}
/**
* Returns a view of a multimap where each value is transformed by a function.
* All other properties of the multimap, such as iteration order, are left
* intact. For example, the code: <pre> {@code
*
* Multimap<String, Integer> multimap =
* ImmutableSetMultimap.of("a", 2, "b", -3, "b", -3, "a", 4, "c", 6);
* Function<Integer, String> square = new Function<Integer, String>() {
* public String apply(Integer in) {
* return Integer.toString(in * in);
* }
* };
* Multimap<String, String> transformed =
* Multimaps.transformValues(multimap, square);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[4, 16], b=[9, 9], c=[36]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is. The {@code equals} and {@code hashCode} methods
* of the returned multimap are meaningless, since there is not a definition
* of {@code equals} or {@code hashCode} for general collections, and
* {@code get()} will return a general {@code Collection} as opposed to a
* {@code List} or a {@code Set}.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> Multimap<K, V2> transformValues(Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a {@code ListMultimap} where each value is transformed by
* a function. All other properties of the multimap, such as iteration order,
* are left intact. For example, the code: <pre> {@code
*
* ListMultimap<String, Integer> multimap
* = ImmutableListMultimap.of("a", 4, "a", 16, "b", 9);
* Function<Integer, Double> sqrt =
* new Function<Integer, Double>() {
* public Double apply(Integer in) {
* return Math.sqrt((int) in);
* }
* };
* ListMultimap<String, Double> transformed = Multimaps.transformValues(map,
* sqrt);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[2.0, 4.0], b=[3.0]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> ListMultimap<K, V2> transformValues(ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a multimap where each value is transformed by a function.
* All other properties of the multimap, such as iteration order, are left
* intact. For example, the code: <pre> {@code
*
* Multimap<String, Integer> multimap =
* ImmutableSetMultimap.of("a", 2, "b", -3, "b", -3, "a", 4, "c", 6);
* Function<Integer, String> square = new Function<Integer, String>() {
* public String apply(Integer in) {
* return Integer.toString(in * in);
* }
* };
* Multimap<String, String> transformed =
* Multimaps.transformValues(multimap, square);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[4, 16], b=[9, 9], c=[36]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is. The {@code equals} and {@code hashCode} methods
* of the returned multimap are meaningless, since there is not a definition
* of {@code equals} or {@code hashCode} for general collections, and
* {@code get()} will return a general {@code Collection} as opposed to a
* {@code List} or a {@code Set}.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> Multimap<K, V2> transformValues(Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a {@code ListMultimap} where each value is transformed by
* a function. All other properties of the multimap, such as iteration order,
* are left intact. For example, the code: <pre> {@code
*
* ListMultimap<String, Integer> multimap
* = ImmutableListMultimap.of("a", 4, "a", 16, "b", 9);
* Function<Integer, Double> sqrt =
* new Function<Integer, Double>() {
* public Double apply(Integer in) {
* return Math.sqrt((int) in);
* }
* };
* ListMultimap<String, Double> transformed = Multimaps.transformValues(map,
* sqrt);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[2.0, 4.0], b=[3.0]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> ListMultimap<K, V2> transformValues(ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a multimap where each value is transformed by a function.
* All other properties of the multimap, such as iteration order, are left
* intact. For example, the code: <pre> {@code
*
* Multimap<String, Integer> multimap =
* ImmutableSetMultimap.of("a", 2, "b", -3, "b", -3, "a", 4, "c", 6);
* Function<Integer, String> square = new Function<Integer, String>() {
* public String apply(Integer in) {
* return Integer.toString(in * in);
* }
* };
* Multimap<String, String> transformed =
* Multimaps.transformValues(multimap, square);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[4, 16], b=[9, 9], c=[36]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is. The {@code equals} and {@code hashCode} methods
* of the returned multimap are meaningless, since there is not a definition
* of {@code equals} or {@code hashCode} for general collections, and
* {@code get()} will return a general {@code Collection} as opposed to a
* {@code List} or a {@code Set}.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> Multimap<K, V2> transformValues(Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a {@code ListMultimap} where each value is transformed by
* a function. All other properties of the multimap, such as iteration order,
* are left intact. For example, the code: <pre> {@code
*
* ListMultimap<String, Integer> multimap
* = ImmutableListMultimap.of("a", 4, "a", 16, "b", 9);
* Function<Integer, Double> sqrt =
* new Function<Integer, Double>() {
* public Double apply(Integer in) {
* return Math.sqrt((int) in);
* }
* };
* ListMultimap<String, Double> transformed = Multimaps.transformValues(map,
* sqrt);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[2.0, 4.0], b=[3.0]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> ListMultimap<K, V2> transformValues(ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a multimap where each value is transformed by a function.
* All other properties of the multimap, such as iteration order, are left
* intact. For example, the code: <pre> {@code
*
* Multimap<String, Integer> multimap =
* ImmutableSetMultimap.of("a", 2, "b", -3, "b", -3, "a", 4, "c", 6);
* Function<Integer, String> square = new Function<Integer, String>() {
* public String apply(Integer in) {
* return Integer.toString(in * in);
* }
* };
* Multimap<String, String> transformed =
* Multimaps.transformValues(multimap, square);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[4, 16], b=[9, 9], c=[36]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is. The {@code equals} and {@code hashCode} methods
* of the returned multimap are meaningless, since there is not a definition
* of {@code equals} or {@code hashCode} for general collections, and
* {@code get()} will return a general {@code Collection} as opposed to a
* {@code List} or a {@code Set}.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> Multimap<K, V2> transformValues(Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a {@code ListMultimap} where each value is transformed by
* a function. All other properties of the multimap, such as iteration order,
* are left intact. For example, the code: <pre> {@code
*
* ListMultimap<String, Integer> multimap
* = ImmutableListMultimap.of("a", 4, "a", 16, "b", 9);
* Function<Integer, Double> sqrt =
* new Function<Integer, Double>() {
* public Double apply(Integer in) {
* return Math.sqrt((int) in);
* }
* };
* ListMultimap<String, Double> transformed = Multimaps.transformValues(map,
* sqrt);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[2.0, 4.0], b=[3.0]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> ListMultimap<K, V2> transformValues(ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a multimap where each value is transformed by a function.
* All other properties of the multimap, such as iteration order, are left
* intact. For example, the code: <pre> {@code
*
* Multimap<String, Integer> multimap =
* ImmutableSetMultimap.of("a", 2, "b", -3, "b", -3, "a", 4, "c", 6);
* Function<Integer, String> square = new Function<Integer, String>() {
* public String apply(Integer in) {
* return Integer.toString(in * in);
* }
* };
* Multimap<String, String> transformed =
* Multimaps.transformValues(multimap, square);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[4, 16], b=[9, 9], c=[36]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is. The {@code equals} and {@code hashCode} methods
* of the returned multimap are meaningless, since there is not a definition
* of {@code equals} or {@code hashCode} for general collections, and
* {@code get()} will return a general {@code Collection} as opposed to a
* {@code List} or a {@code Set}.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> Multimap<K, V2> transformValues(
Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}
/**
* Returns a view of a {@code ListMultimap} where each value is transformed by
* a function. All other properties of the multimap, such as iteration order,
* are left intact. For example, the code: <pre> {@code
*
* ListMultimap<String, Integer> multimap
* = ImmutableListMultimap.of("a", 4, "a", 16, "b", 9);
* Function<Integer, Double> sqrt =
* new Function<Integer, Double>() {
* public Double apply(Integer in) {
* return Math.sqrt((int) in);
* }
* };
* ListMultimap<String, Double> transformed = Multimaps.transformValues(map,
* sqrt);
* System.out.println(transformed);}</pre>
*
* ... prints {@code {a=[2.0, 4.0], b=[3.0]}}.
*
* <p>Changes in the underlying multimap are reflected in this view.
* Conversely, this view supports removal operations, and these are reflected
* in the underlying multimap.
*
* <p>It's acceptable for the underlying multimap to contain null keys, and
* even null values provided that the function is capable of accepting null
* input. The transformed multimap might contain null values, if the function
* sometimes gives a null result.
*
* <p>The returned multimap is not thread-safe or serializable, even if the
* underlying multimap is.
*
* <p>The function is applied lazily, invoked when needed. This is necessary
* for the returned multimap to be a view, but it means that the function will
* be applied many times for bulk operations like
* {@link Multimap#containsValue} and {@code Multimap.toString()}. For this to
* perform well, {@code function} should be fast. To avoid lazy evaluation
* when the returned multimap doesn't need to be a view, copy the returned
* multimap into a new multimap of your choosing.
*
* @since 7.0
*/
public static <K, V1, V2> ListMultimap<K, V2> transformValues(
ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
checkNotNull(function);
EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
return transformEntries(fromMultimap, transformer);
}