@GwtCompatible(emulated=true) public final class Maps extends Object
Map instances (including instances of SortedMap, BiMap, etc.). Also see this class's counterparts Lists, Sets and Queues. See the Guava User Guide article on Maps.
| Modifier and Type | Class and Description |
|---|---|
static interface | Maps.EntryTransformer<K,V1,V2> A transformation of the value of a key-value pair, using both key and value as inputs. |
| Modifier and Type | Method and Description |
|---|---|
static <A,B> Converter<A,B> | asConverter(BiMap<A,B> bimap) Returns a Converter that converts values using bimap.get(), and whose inverse view converts values using bimap.inverse().get(). |
static <K,V> NavigableMap<K,V> | asMap(NavigableSet<K> set, Function<? super K,V> function) Returns a view of the navigable set as a map, mapping keys from the set according to the specified function. |
static <K,V> Map<K,V> | asMap(Set<K> set, Function<? super K,V> function) Returns a live Map view whose keys are the contents of set and whose values are computed on demand using function. |
static <K,V> SortedMap<K,V> | asMap(SortedSet<K> set, Function<? super K,V> function) Returns a view of the sorted set as a map, mapping keys from the set according to the specified function. |
static <K,V> MapDifference<K,V> | difference(Map<? extends K,? extends V> left, Map<? extends K,? extends V> right) Computes the difference between two maps. |
static <K,V> MapDifference<K,V> | difference(Map<? extends K,? extends V> left, Map<? extends K,? extends V> right, Equivalence<? super V> valueEquivalence) Computes the difference between two maps. |
static <K,V> SortedMapDifference<K,V> | difference(SortedMap<K,? extends V> left, Map<? extends K,? extends V> right) Computes the difference between two sorted maps, using the comparator of the left map, or Ordering.natural() if the left map uses the natural ordering of its elements. |
static <K,V> BiMap<K,V> | filterEntries(BiMap<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate) Returns a bimap containing the mappings in unfiltered that satisfy a predicate. |
static <K,V> Map<K,V> | filterEntries(Map<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate) Returns a map containing the mappings in unfiltered that satisfy a predicate. |
static <K,V> NavigableMap<K,V> | filterEntries(NavigableMap<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate) Returns a sorted map containing the mappings in unfiltered that satisfy a predicate. |
static <K,V> SortedMap<K,V> | filterEntries(SortedMap<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate) Returns a sorted map containing the mappings in unfiltered that satisfy a predicate. |
static <K,V> BiMap<K,V> | filterKeys(BiMap<K,V> unfiltered, Predicate<? super K> keyPredicate) Returns a bimap containing the mappings in unfiltered whose keys satisfy a predicate. |
static <K,V> Map<K,V> | filterKeys(Map<K,V> unfiltered, Predicate<? super K> keyPredicate) Returns a map containing the mappings in unfiltered whose keys satisfy a predicate. |
static <K,V> NavigableMap<K,V> | filterKeys(NavigableMap<K,V> unfiltered, Predicate<? super K> keyPredicate) Returns a navigable map containing the mappings in unfiltered whose keys satisfy a predicate. |
static <K,V> SortedMap<K,V> | filterKeys(SortedMap<K,V> unfiltered, Predicate<? super K> keyPredicate) Returns a sorted map containing the mappings in unfiltered whose keys satisfy a predicate. |
static <K,V> BiMap<K,V> | filterValues(BiMap<K,V> unfiltered, Predicate<? super V> valuePredicate) Returns a bimap containing the mappings in unfiltered whose values satisfy a predicate. |
static <K,V> Map<K,V> | filterValues(Map<K,V> unfiltered, Predicate<? super V> valuePredicate) Returns a map containing the mappings in unfiltered whose values satisfy a predicate. |
static <K,V> NavigableMap<K,V> | filterValues(NavigableMap<K,V> unfiltered, Predicate<? super V> valuePredicate) Returns a navigable map containing the mappings in unfiltered whose values satisfy a predicate. |
static <K,V> SortedMap<K,V> | filterValues(SortedMap<K,V> unfiltered, Predicate<? super V> valuePredicate) Returns a sorted map containing the mappings in unfiltered whose values satisfy a predicate. |
static ImmutableMap<String,String> | fromProperties(Properties properties) Creates an ImmutableMap<String, String> from a Properties instance. |
static <K,V> Map.Entry<K,V> | immutableEntry(K key, V value) Returns an immutable map entry with the specified key and value. |
static <K extends Enum<K>,V> | immutableEnumMap(Map<K,? extends V> map) Returns an immutable map instance containing the given entries. |
static <K,V> ConcurrentMap<K,V> | newConcurrentMap() Returns a general-purpose instance of ConcurrentMap, which supports all optional operations of the ConcurrentMap interface. |
static <K extends Enum<K>,V> | newEnumMap(Class<K> type) Creates an EnumMap instance. |
static <K extends Enum<K>,V> | newEnumMap(Map<K,? extends V> map) Creates an EnumMap with the same mappings as the specified map. |
static <K,V> HashMap<K,V> | newHashMap() Creates a mutable, empty HashMap instance. |
static <K,V> HashMap<K,V> | newHashMap(Map<? extends K,? extends V> map) Creates a mutable HashMap instance with the same mappings as the specified map. |
static <K,V> HashMap<K,V> | newHashMapWithExpectedSize(int expectedSize) Creates a HashMap instance, with a high enough "initial capacity" that it should hold expectedSize elements without growth. |
static <K,V> IdentityHashMap<K,V> | newIdentityHashMap() Creates an IdentityHashMap instance. |
static <K,V> LinkedHashMap<K,V> | newLinkedHashMap() Creates a mutable, empty, insertion-ordered LinkedHashMap instance. |
static <K,V> LinkedHashMap<K,V> | newLinkedHashMap(Map<? extends K,? extends V> map) Creates a mutable, insertion-ordered LinkedHashMap instance with the same mappings as the specified map. |
static <K,V> LinkedHashMap<K,V> | newLinkedHashMapWithExpectedSize(int expectedSize) Creates a LinkedHashMap instance, with a high enough "initial capacity" that it should hold expectedSize elements without growth. |
static <K extends Comparable,V> | newTreeMap() Creates a mutable, empty TreeMap instance using the natural ordering of its elements. |
static <C,K extends C,V> | newTreeMap(Comparator<C> comparator) Creates a mutable, empty TreeMap instance using the given comparator. |
static <K,V> TreeMap<K,V> | newTreeMap(SortedMap<K,? extends V> map) Creates a mutable TreeMap instance with the same mappings as the specified map and using the same ordering as the specified map. |
static <K,V> BiMap<K,V> | synchronizedBiMap(BiMap<K,V> bimap) Returns a synchronized (thread-safe) bimap backed by the specified bimap. |
static <K,V> NavigableMap<K,V> | synchronizedNavigableMap(NavigableMap<K,V> navigableMap) Returns a synchronized (thread-safe) navigable map backed by the specified navigable map. |
static <K,V> ImmutableMap<K,V> | toMap(Iterable<K> keys, Function<? super K,V> valueFunction) Returns an immutable map whose keys are the distinct elements of keys and whose value for each key was computed by valueFunction. |
static <K,V> ImmutableMap<K,V> | toMap(Iterator<K> keys, Function<? super K,V> valueFunction) Returns an immutable map whose keys are the distinct elements of keys and whose value for each key was computed by valueFunction. |
static <K,V1,V2> Map<K,V2> | transformEntries(Map<K,V1> fromMap, Maps.EntryTransformer<? super K,? super V1,V2> transformer) Returns a view of a map whose values are derived from the original map's entries. |
static <K,V1,V2> NavigableMap<K,V2> | transformEntries(NavigableMap<K,V1> fromMap, Maps.EntryTransformer<? super K,? super V1,V2> transformer) Returns a view of a navigable map whose values are derived from the original navigable map's entries. |
static <K,V1,V2> SortedMap<K,V2> | transformEntries(SortedMap<K,V1> fromMap, Maps.EntryTransformer<? super K,? super V1,V2> transformer) Returns a view of a sorted map whose values are derived from the original sorted map's entries. |
static <K,V1,V2> Map<K,V2> | transformValues(Map<K,V1> fromMap, Function<? super V1,V2> function) Returns a view of a map where each value is transformed by a function. |
static <K,V1,V2> NavigableMap<K,V2> | transformValues(NavigableMap<K,V1> fromMap, Function<? super V1,V2> function) Returns a view of a navigable map where each value is transformed by a function. |
static <K,V1,V2> SortedMap<K,V2> | transformValues(SortedMap<K,V1> fromMap, Function<? super V1,V2> function) Returns a view of a sorted map where each value is transformed by a function. |
static <K,V> ImmutableMap<K,V> | uniqueIndex(Iterable<V> values, Function<? super V,K> keyFunction) Returns a map with the given values, indexed by keys derived from those values. |
static <K,V> ImmutableMap<K,V> | uniqueIndex(Iterator<V> values, Function<? super V,K> keyFunction) Returns a map with the given values, indexed by keys derived from those values. |
static <K,V> BiMap<K,V> | unmodifiableBiMap(BiMap<? extends K,? extends V> bimap) Returns an unmodifiable view of the specified bimap. |
static <K,V> NavigableMap<K,V> | unmodifiableNavigableMap(NavigableMap<K,V> map) Returns an unmodifiable view of the specified navigable map. |
@GwtCompatible(serializable=true) @Beta public static <K extends Enum<K>,V> ImmutableMap<K,V> immutableEnumMap(Map<K,? extends V> map)
EnumMap. The iteration order of the returned map follows the enum's iteration order, not the order in which the elements appear in the given map.
map - the map to make an immutable copy ofpublic static <K,V> HashMap<K,V> newHashMap()
HashMap instance. Note: if mutability is not required, use ImmutableMap.of() instead.
Note: if K is an enum type, use newEnumMap(java.lang.Class<K>) instead.
HashMappublic static <K,V> HashMap<K,V> newHashMapWithExpectedSize(int expectedSize)
HashMap instance, with a high enough "initial capacity" that it should hold expectedSize elements without growth. This behavior cannot be broadly guaranteed, but it is observed to be true for OpenJDK 1.7. It also can't be guaranteed that the method isn't inadvertently oversizing the returned map.expectedSize - the number of entries you expect to add to the returned mapHashMap with enough capacity to hold expectedSize entries without resizingIllegalArgumentException - if expectedSize is negativepublic static <K,V> HashMap<K,V> newHashMap(Map<? extends K,? extends V> map)
HashMap instance with the same mappings as the specified map. Note: if mutability is not required, use ImmutableMap.copyOf(Map) instead.
Note: if K is an Enum type, use newEnumMap(java.lang.Class<K>) instead.
map - the mappings to be placed in the new mapHashMap initialized with the mappings from mappublic static <K,V> LinkedHashMap<K,V> newLinkedHashMap()
LinkedHashMap instance. Note: if mutability is not required, use ImmutableMap.of() instead.
LinkedHashMappublic static <K,V> LinkedHashMap<K,V> newLinkedHashMapWithExpectedSize(int expectedSize)
LinkedHashMap instance, with a high enough "initial capacity" that it should hold expectedSize elements without growth. This behavior cannot be broadly guaranteed, but it is observed to be true for OpenJDK 1.7. It also can't be guaranteed that the method isn't inadvertently oversizing the returned map.expectedSize - the number of entries you expect to add to the returned mapLinkedHashMap with enough capacity to hold expectedSize entries without resizingIllegalArgumentException - if expectedSize is negativepublic static <K,V> LinkedHashMap<K,V> newLinkedHashMap(Map<? extends K,? extends V> map)
LinkedHashMap instance with the same mappings as the specified map. Note: if mutability is not required, use ImmutableMap.copyOf(Map) instead.
map - the mappings to be placed in the new mapLinkedHashMap initialized with the mappings from mappublic static <K,V> ConcurrentMap<K,V> newConcurrentMap()
ConcurrentMap, which supports all optional operations of the ConcurrentMap interface. It does not permit null keys or values. It is serializable. This is currently accomplished by calling MapMaker.makeMap().
It is preferable to use MapMaker directly (rather than through this method), as it presents numerous useful configuration options, such as the concurrency level, load factor, key/value reference types, and value computation.
ConcurrentMappublic static <K extends Comparable,V> TreeMap<K,V> newTreeMap()
TreeMap instance using the natural ordering of its elements. Note: if mutability is not required, use ImmutableSortedMap.of() instead.
TreeMappublic static <K,V> TreeMap<K,V> newTreeMap(SortedMap<K,? extends V> map)
TreeMap instance with the same mappings as the specified map and using the same ordering as the specified map. Note: if mutability is not required, use ImmutableSortedMap.copyOfSorted(SortedMap) instead.
map - the sorted map whose mappings are to be placed in the new map and whose comparator is to be used to sort the new mapTreeMap initialized with the mappings from map and using the comparator of mappublic static <C,K extends C,V> TreeMap<K,V> newTreeMap(@Nullable Comparator<C> comparator)
TreeMap instance using the given comparator. Note: if mutability is not required, use ImmutableSortedMap.orderedBy(comparator).build() instead.
comparator - the comparator to sort the keys withTreeMappublic static <K extends Enum<K>,V> EnumMap<K,V> newEnumMap(Class<K> type)
EnumMap instance.type - the key type for this mapEnumMappublic static <K extends Enum<K>,V> EnumMap<K,V> newEnumMap(Map<K,? extends V> map)
EnumMap with the same mappings as the specified map.map - the map from which to initialize this EnumMapEnumMap initialized with the mappings from mapIllegalArgumentException - if m is not an EnumMap instance and contains no mappingspublic static <K,V> IdentityHashMap<K,V> newIdentityHashMap()
IdentityHashMap instance.IdentityHashMappublic static <K,V> MapDifference<K,V> difference(Map<? extends K,? extends V> left, Map<? extends K,? extends V> right)
Since this method uses HashMap instances internally, the keys of the supplied maps must be well-behaved with respect to Object.equals(java.lang.Object) and Object.hashCode().
Note:If you only need to know whether two maps have the same mappings, call left.equals(right) instead of this method.
left - the map to treat as the "left" map for purposes of comparisonright - the map to treat as the "right" map for purposes of comparison@Beta public static <K,V> MapDifference<K,V> difference(Map<? extends K,? extends V> left, Map<? extends K,? extends V> right, Equivalence<? super V> valueEquivalence)
Values are compared using a provided equivalence, in the case of equality, the value on the 'left' is returned in the difference.
Since this method uses HashMap instances internally, the keys of the supplied maps must be well-behaved with respect to Object.equals(java.lang.Object) and Object.hashCode().
left - the map to treat as the "left" map for purposes of comparisonright - the map to treat as the "right" map for purposes of comparisonvalueEquivalence - the equivalence relationship to use to compare valuespublic static <K,V> SortedMapDifference<K,V> difference(SortedMap<K,? extends V> left, Map<? extends K,? extends V> right)
Ordering.natural() if the left map uses the natural ordering of its elements. This difference is an immutable snapshot of the state of the maps at the time this method is called. It will never change, even if the maps change at a later time. Since this method uses TreeMap instances internally, the keys of the right map must all compare as distinct according to the comparator of the left map.
Note:If you only need to know whether two sorted maps have the same mappings, call left.equals(right) instead of this method.
left - the map to treat as the "left" map for purposes of comparisonright - the map to treat as the "right" map for purposes of comparisonpublic static <K,V> Map<K,V> asMap(Set<K> set, Function<? super K,V> function)
Map view whose keys are the contents of set and whose values are computed on demand using function. To get an immutable copy instead, use toMap(Iterable, Function). Specifically, for each k in the backing set, the returned map has an entry mapping k to function.apply(k). The keySet, values, and entrySet views of the returned map iterate in the same order as the backing set.
Modifications to the backing set are read through to the returned map. The returned map supports removal operations if the backing set does. Removal operations write through to the backing set. The returned map does not support put operations.
Warning: If the function rejects null, caution is required to make sure the set does not contain null, because the view cannot stop null from being added to the set.
Warning: This method assumes that for any instance k of key type K, k.equals(k2) implies that k2 is also of type K. Using a key type for which this may not hold, such as ArrayList, may risk a ClassCastException when calling methods on the resulting map view.
public static <K,V> SortedMap<K,V> asMap(SortedSet<K> set, Function<? super K,V> function)
Specifically, for each k in the backing set, the returned map has an entry mapping k to function.apply(k). The keySet, values, and entrySet views of the returned map iterate in the same order as the backing set.
Modifications to the backing set are read through to the returned map. The returned map supports removal operations if the backing set does. Removal operations write through to the backing set. The returned map does not support put operations.
Warning: If the function rejects null, caution is required to make sure the set does not contain null, because the view cannot stop null from being added to the set.
Warning: This method assumes that for any instance k of key type K, k.equals(k2) implies that k2 is also of type K. Using a key type for which this may not hold, such as ArrayList, may risk a ClassCastException when calling methods on the resulting map view.
@GwtIncompatible(value="NavigableMap") public static <K,V> NavigableMap<K,V> asMap(NavigableSet<K> set, Function<? super K,V> function)
Specifically, for each k in the backing set, the returned map has an entry mapping k to function.apply(k). The keySet, values, and entrySet views of the returned map iterate in the same order as the backing set.
Modifications to the backing set are read through to the returned map. The returned map supports removal operations if the backing set does. Removal operations write through to the backing set. The returned map does not support put operations.
Warning: If the function rejects null, caution is required to make sure the set does not contain null, because the view cannot stop null from being added to the set.
Warning: This method assumes that for any instance k of key type K, k.equals(k2) implies that k2 is also of type K. Using a key type for which this may not hold, such as ArrayList, may risk a ClassCastException when calling methods on the resulting map view.
public static <K,V> ImmutableMap<K,V> toMap(Iterable<K> keys, Function<? super K,V> valueFunction)
keys and whose value for each key was computed by valueFunction. The map's iteration order is the order of the first appearance of each key in keys. When there are multiple instances of a key in keys, it is unspecified whether valueFunction will be applied to more than one instance of that key and, if it is, which result will be mapped to that key in the returned map.
If keys is a Set, a live view can be obtained instead of a copy using asMap(Set, Function).
NullPointerException - if any element of keys is null, or if valueFunction produces null for any keypublic static <K,V> ImmutableMap<K,V> toMap(Iterator<K> keys, Function<? super K,V> valueFunction)
keys and whose value for each key was computed by valueFunction. The map's iteration order is the order of the first appearance of each key in keys. When there are multiple instances of a key in keys, it is unspecified whether valueFunction will be applied to more than one instance of that key and, if it is, which result will be mapped to that key in the returned map.
NullPointerException - if any element of keys is null, or if valueFunction produces null for any keypublic static <K,V> ImmutableMap<K,V> uniqueIndex(Iterable<V> values, Function<? super V,K> keyFunction)
values, indexed by keys derived from those values. In other words, each input value produces an entry in the map whose key is the result of applying keyFunction to that value. These entries appear in the same order as the input values. Example usage: Color red = new Color("red", 255, 0, 0); ... ImmutableSet<Color> allColors = ImmutableSet.of(red, green, blue); Map<String, Color> colorForName = uniqueIndex(allColors, toStringFunction()); assertThat(colorForName).containsEntry("red", red); If your index may associate multiple values with each key, use Multimaps.index.
values - the values to use when constructing the MapkeyFunction - the function used to produce the key for each valuekeyFunction on each value in the input collection to that valueIllegalArgumentException - if keyFunction produces the same key for more than one value in the input collectionNullPointerException - if any elements of values is null, or if keyFunction produces null for any valuepublic static <K,V> ImmutableMap<K,V> uniqueIndex(Iterator<V> values, Function<? super V,K> keyFunction)
values, indexed by keys derived from those values. In other words, each input value produces an entry in the map whose key is the result of applying keyFunction to that value. These entries appear in the same order as the input values. Example usage: Color red = new Color("red", 255, 0, 0); ... Iterator<Color> allColors = ImmutableSet.of(red, green, blue).iterator(); Map<String, Color> colorForName = uniqueIndex(allColors, toStringFunction()); assertThat(colorForName).containsEntry("red", red); If your index may associate multiple values with each key, use Multimaps.index.
values - the values to use when constructing the MapkeyFunction - the function used to produce the key for each valuekeyFunction on each value in the input collection to that valueIllegalArgumentException - if keyFunction produces the same key for more than one value in the input collectionNullPointerException - if any elements of values is null, or if keyFunction produces null for any value@GwtIncompatible(value="java.util.Properties") public static ImmutableMap<String,String> fromProperties(Properties properties)
ImmutableMap<String, String> from a Properties instance. Properties normally derive from Map<Object, Object>, but they typically contain strings, which is awkward. This method lets you get a plain-old-Map out of a Properties.properties - a Properties object to be convertedpropertiesClassCastException - if any key in Properties is not a StringNullPointerException - if any key or value in Properties is null@GwtCompatible(serializable=true) public static <K,V> Map.Entry<K,V> immutableEntry(@Nullable K key, @Nullable V value)
Map.Entry.setValue(V) operation throws an UnsupportedOperationException. The returned entry is serializable.
key - the key to be associated with the returned entryvalue - the value to be associated with the returned entry@Beta public static <A,B> Converter<A,B> asConverter(BiMap<A,B> bimap)
Converter that converts values using bimap.get(), and whose inverse view converts values using bimap.inverse().get(). To use a plain Map as a Function, see Functions.forMap(Map) or Functions.forMap(Map, Object).
public static <K,V> BiMap<K,V> synchronizedBiMap(BiMap<K,V> bimap)
It is imperative that the user manually synchronize on the returned map when accessing any of its collection views:
BiMap<Long, String> map = Maps.synchronizedBiMap( HashBiMap.<Long, String>create()); ... Set<Long> set = map.keySet(); // Needn't be in synchronized block ... synchronized (map) { // Synchronizing on map, not set! Iterator<Long> it = set.iterator(); // Must be in synchronized block while (it.hasNext()) { foo(it.next()); } } Failure to follow this advice may result in non-deterministic behavior.
The returned bimap will be serializable if the specified bimap is serializable.
bimap - the bimap to be wrapped in a synchronized viewpublic static <K,V> BiMap<K,V> unmodifiableBiMap(BiMap<? extends K,? extends V> bimap)
UnsupportedOperationException. The returned bimap will be serializable if the specified bimap is serializable.
bimap - the bimap for which an unmodifiable view is to be returnedpublic static <K,V1,V2> Map<K,V2> transformValues(Map<K,V1> fromMap, Function<? super V1,V2> function)
Map<String, Integer> map = ImmutableMap.of("a", 4, "b", 9); Function<Integer, Double> sqrt = new Function<Integer, Double>() { public Double apply(Integer in) { return Math.sqrt((int) in); } }; Map<String, Double> transformed = Maps.transformValues(map, sqrt); System.out.println(transformed); ... prints {a=2.0, b=3.0}. Changes in the underlying map are reflected in this view. Conversely, this view supports removal operations, and these are reflected in the underlying map.
It's acceptable for the underlying map to contain null keys, and even null values provided that the function is capable of accepting null input. The transformed map might contain null values, if the function sometimes gives a null result.
The returned map is not thread-safe or serializable, even if the underlying map is.
The function is applied lazily, invoked when needed. This is necessary for the returned map to be a view, but it means that the function will be applied many times for bulk operations like Map.containsValue(java.lang.Object) and Map.toString(). For this to perform well, function should be fast. To avoid lazy evaluation when the returned map doesn't need to be a view, copy the returned map into a new map of your choosing.
public static <K,V1,V2> SortedMap<K,V2> transformValues(SortedMap<K,V1> fromMap, Function<? super V1,V2> function)
SortedMap<String, Integer> map = ImmutableSortedMap.of("a", 4, "b", 9); Function<Integer, Double> sqrt = new Function<Integer, Double>() { public Double apply(Integer in) { return Math.sqrt((int) in); } }; SortedMap<String, Double> transformed = Maps.transformValues(map, sqrt); System.out.println(transformed); ... prints {a=2.0, b=3.0}. Changes in the underlying map are reflected in this view. Conversely, this view supports removal operations, and these are reflected in the underlying map.
It's acceptable for the underlying map to contain null keys, and even null values provided that the function is capable of accepting null input. The transformed map might contain null values, if the function sometimes gives a null result.
The returned map is not thread-safe or serializable, even if the underlying map is.
The function is applied lazily, invoked when needed. This is necessary for the returned map to be a view, but it means that the function will be applied many times for bulk operations like Map.containsValue(java.lang.Object) and Map.toString(). For this to perform well, function should be fast. To avoid lazy evaluation when the returned map doesn't need to be a view, copy the returned map into a new map of your choosing.
@GwtIncompatible(value="NavigableMap") public static <K,V1,V2> NavigableMap<K,V2> transformValues(NavigableMap<K,V1> fromMap, Function<? super V1,V2> function)
NavigableMap<String, Integer> map = Maps.newTreeMap(); map.put("a", 4); map.put("b", 9); Function<Integer, Double> sqrt = new Function<Integer, Double>() { public Double apply(Integer in) { return Math.sqrt((int) in); } }; NavigableMap<String, Double> transformed = Maps.transformNavigableValues(map, sqrt); System.out.println(transformed); ... prints {a=2.0, b=3.0}. Changes in the underlying map are reflected in this view. Conversely, this view supports removal operations, and these are reflected in the underlying map. It's acceptable for the underlying map to contain null keys, and even null values provided that the function is capable of accepting null input. The transformed map might contain null values, if the function sometimes gives a null result.
The returned map is not thread-safe or serializable, even if the underlying map is.
The function is applied lazily, invoked when needed. This is necessary for the returned map to be a view, but it means that the function will be applied many times for bulk operations like Map.containsValue(java.lang.Object) and Map.toString(). For this to perform well, function should be fast. To avoid lazy evaluation when the returned map doesn't need to be a view, copy the returned map into a new map of your choosing.
public static <K,V1,V2> Map<K,V2> transformEntries(Map<K,V1> fromMap, Maps.EntryTransformer<? super K,? super V1,V2> transformer)
transformValues(java.util.Map<K, V1>, com.google.common.base.Function<? super V1, V2>), this method's entry-transformation logic may depend on the key as well as the value. All other properties of the transformed map, such as iteration order, are left intact. For example, the code:
Map<String, Boolean> options = ImmutableMap.of("verbose", true, "sort", false); EntryTransformer<String, Boolean, String> flagPrefixer = new EntryTransformer<String, Boolean, String>() { public String transformEntry(String key, Boolean value) { return value ? key : "no" + key; } }; Map<String, String> transformed = Maps.transformEntries(options, flagPrefixer); System.out.println(transformed); ... prints {verbose=verbose, sort=nosort}. Changes in the underlying map are reflected in this view. Conversely, this view supports removal operations, and these are reflected in the underlying map.
It's acceptable for the underlying map to contain null keys and null values provided that the transformer is capable of accepting null inputs. The transformed map might contain null values if the transformer sometimes gives a null result.
The returned map is not thread-safe or serializable, even if the underlying map is.
The transformer is applied lazily, invoked when needed. This is necessary for the returned map to be a view, but it means that the transformer will be applied many times for bulk operations like Map.containsValue(java.lang.Object) and Object.toString(). For this to perform well, transformer should be fast. To avoid lazy evaluation when the returned map doesn't need to be a view, copy the returned map into a new map of your choosing.
Warning: This method assumes that for any instance k of EntryTransformer key type K, k.equals(k2) implies that k2 is also of type K. Using an EntryTransformer key type for which this may not hold, such as ArrayList, may risk a ClassCastException when calling methods on the transformed map.
public static <K,V1,V2> SortedMap<K,V2> transformEntries(SortedMap<K,V1> fromMap, Maps.EntryTransformer<? super K,? super V1,V2> transformer)
transformValues(java.util.Map<K, V1>, com.google.common.base.Function<? super V1, V2>), this method's entry-transformation logic may depend on the key as well as the value. All other properties of the transformed map, such as iteration order, are left intact. For example, the code:
Map<String, Boolean> options = ImmutableSortedMap.of("verbose", true, "sort", false); EntryTransformer<String, Boolean, String> flagPrefixer = new EntryTransformer<String, Boolean, String>() { public String transformEntry(String key, Boolean value) { return value ? key : "yes" + key; } }; SortedMap<String, String> transformed = Maps.transformEntries(options, flagPrefixer); System.out.println(transformed); ... prints {sort=yessort, verbose=verbose}. Changes in the underlying map are reflected in this view. Conversely, this view supports removal operations, and these are reflected in the underlying map.
It's acceptable for the underlying map to contain null keys and null values provided that the transformer is capable of accepting null inputs. The transformed map might contain null values if the transformer sometimes gives a null result.
The returned map is not thread-safe or serializable, even if the underlying map is.
The transformer is applied lazily, invoked when needed. This is necessary for the returned map to be a view, but it means that the transformer will be applied many times for bulk operations like Map.containsValue(java.lang.Object) and Object.toString(). For this to perform well, transformer should be fast. To avoid lazy evaluation when the returned map doesn't need to be a view, copy the returned map into a new map of your choosing.
Warning: This method assumes that for any instance k of EntryTransformer key type K, k.equals(k2) implies that k2 is also of type K. Using an EntryTransformer key type for which this may not hold, such as ArrayList, may risk a ClassCastException when calling methods on the transformed map.
@GwtIncompatible(value="NavigableMap") public static <K,V1,V2> NavigableMap<K,V2> transformEntries(NavigableMap<K,V1> fromMap, Maps.EntryTransformer<? super K,? super V1,V2> transformer)
transformValues(java.util.Map<K, V1>, com.google.common.base.Function<? super V1, V2>), this method's entry-transformation logic may depend on the key as well as the value. All other properties of the transformed map, such as iteration order, are left intact. For example, the code:
NavigableMap<String, Boolean> options = Maps.newTreeMap(); options.put("verbose", false); options.put("sort", true); EntryTransformer<String, Boolean, String> flagPrefixer = new EntryTransformer<String, Boolean, String>() { public String transformEntry(String key, Boolean value) { return value ? key : ("yes" + key); } }; NavigableMap<String, String> transformed = LabsMaps.transformNavigableEntries(options, flagPrefixer); System.out.println(transformed); ... prints {sort=yessort, verbose=verbose}. Changes in the underlying map are reflected in this view. Conversely, this view supports removal operations, and these are reflected in the underlying map.
It's acceptable for the underlying map to contain null keys and null values provided that the transformer is capable of accepting null inputs. The transformed map might contain null values if the transformer sometimes gives a null result.
The returned map is not thread-safe or serializable, even if the underlying map is.
The transformer is applied lazily, invoked when needed. This is necessary for the returned map to be a view, but it means that the transformer will be applied many times for bulk operations like Map.containsValue(java.lang.Object) and Object.toString(). For this to perform well, transformer should be fast. To avoid lazy evaluation when the returned map doesn't need to be a view, copy the returned map into a new map of your choosing.
Warning: This method assumes that for any instance k of EntryTransformer key type K, k.equals(k2) implies that k2 is also of type K. Using an EntryTransformer key type for which this may not hold, such as ArrayList, may risk a ClassCastException when calling methods on the transformed map.
@CheckReturnValue public static <K,V> Map<K,V> filterKeys(Map<K,V> unfiltered, Predicate<? super K> keyPredicate)
unfiltered whose keys satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a key that doesn't satisfy the predicate, the map's put() and putAll() methods throw an IllegalArgumentException.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings whose keys satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: keyPredicate must be consistent with equals, as documented at Predicate.apply(T). Do not provide a predicate such as Predicates.instanceOf(ArrayList.class), which is inconsistent with equals.
@CheckReturnValue public static <K,V> SortedMap<K,V> filterKeys(SortedMap<K,V> unfiltered, Predicate<? super K> keyPredicate)
unfiltered whose keys satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a key that doesn't satisfy the predicate, the map's put() and putAll() methods throw an IllegalArgumentException.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings whose keys satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: keyPredicate must be consistent with equals, as documented at Predicate.apply(T). Do not provide a predicate such as Predicates.instanceOf(ArrayList.class), which is inconsistent with equals.
@GwtIncompatible(value="NavigableMap") @CheckReturnValue public static <K,V> NavigableMap<K,V> filterKeys(NavigableMap<K,V> unfiltered, Predicate<? super K> keyPredicate)
unfiltered whose keys satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a key that doesn't satisfy the predicate, the map's put() and putAll() methods throw an IllegalArgumentException.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings whose keys satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: keyPredicate must be consistent with equals, as documented at Predicate.apply(T). Do not provide a predicate such as Predicates.instanceOf(ArrayList.class), which is inconsistent with equals.
@CheckReturnValue public static <K,V> BiMap<K,V> filterKeys(BiMap<K,V> unfiltered, Predicate<? super K> keyPredicate)
unfiltered whose keys satisfy a predicate. The returned bimap is a live view of unfiltered; changes to one affect the other. The resulting bimap's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the bimap and its views. When given a key that doesn't satisfy the predicate, the bimap's put(), forcePut() and putAll() methods throw an IllegalArgumentException.
When methods such as removeAll() and clear() are called on the filtered bimap or its views, only mappings that satisfy the filter will be removed from the underlying bimap.
The returned bimap isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered bimap's methods, such as size(), iterate across every key in the underlying bimap and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered bimap and use the copy.
Warning: entryPredicate must be consistent with equals , as documented at Predicate.apply(T).
@CheckReturnValue public static <K,V> Map<K,V> filterValues(Map<K,V> unfiltered, Predicate<? super V> valuePredicate)
unfiltered whose values satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a value that doesn't satisfy the predicate, the map's put(), putAll(), and Map.Entry.setValue(V) methods throw an IllegalArgumentException.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings whose values satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: valuePredicate must be consistent with equals, as documented at Predicate.apply(T). Do not provide a predicate such as Predicates.instanceOf(ArrayList.class), which is inconsistent with equals.
@CheckReturnValue public static <K,V> SortedMap<K,V> filterValues(SortedMap<K,V> unfiltered, Predicate<? super V> valuePredicate)
unfiltered whose values satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a value that doesn't satisfy the predicate, the map's put(), putAll(), and Map.Entry.setValue(V) methods throw an IllegalArgumentException.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings whose values satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: valuePredicate must be consistent with equals, as documented at Predicate.apply(T). Do not provide a predicate such as Predicates.instanceOf(ArrayList.class), which is inconsistent with equals.
@GwtIncompatible(value="NavigableMap") @CheckReturnValue public static <K,V> NavigableMap<K,V> filterValues(NavigableMap<K,V> unfiltered, Predicate<? super V> valuePredicate)
unfiltered whose values satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a value that doesn't satisfy the predicate, the map's put(), putAll(), and Map.Entry.setValue(V) methods throw an IllegalArgumentException.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings whose values satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: valuePredicate must be consistent with equals, as documented at Predicate.apply(T). Do not provide a predicate such as Predicates.instanceOf(ArrayList.class), which is inconsistent with equals.
@CheckReturnValue public static <K,V> BiMap<K,V> filterValues(BiMap<K,V> unfiltered, Predicate<? super V> valuePredicate)
unfiltered whose values satisfy a predicate. The returned bimap is a live view of unfiltered; changes to one affect the other. The resulting bimap's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the bimap and its views. When given a value that doesn't satisfy the predicate, the bimap's put(), forcePut() and putAll() methods throw an IllegalArgumentException. Similarly, the map's entries have a Map.Entry.setValue(V) method that throws an IllegalArgumentException when the provided value doesn't satisfy the predicate.
When methods such as removeAll() and clear() are called on the filtered bimap or its views, only mappings that satisfy the filter will be removed from the underlying bimap.
The returned bimap isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered bimap's methods, such as size(), iterate across every value in the underlying bimap and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered bimap and use the copy.
Warning: entryPredicate must be consistent with equals , as documented at Predicate.apply(T).
@CheckReturnValue public static <K,V> Map<K,V> filterEntries(Map<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate)
unfiltered that satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a key/value pair that doesn't satisfy the predicate, the map's put() and putAll() methods throw an IllegalArgumentException. Similarly, the map's entries have a Map.Entry.setValue(V) method that throws an IllegalArgumentException when the existing key and the provided value don't satisfy the predicate.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings that satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: entryPredicate must be consistent with equals, as documented at Predicate.apply(T).
@CheckReturnValue public static <K,V> SortedMap<K,V> filterEntries(SortedMap<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate)
unfiltered that satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a key/value pair that doesn't satisfy the predicate, the map's put() and putAll() methods throw an IllegalArgumentException. Similarly, the map's entries have a Map.Entry.setValue(V) method that throws an IllegalArgumentException when the existing key and the provided value don't satisfy the predicate.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings that satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: entryPredicate must be consistent with equals, as documented at Predicate.apply(T).
@GwtIncompatible(value="NavigableMap") @CheckReturnValue public static <K,V> NavigableMap<K,V> filterEntries(NavigableMap<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate)
unfiltered that satisfy a predicate. The returned map is a live view of unfiltered; changes to one affect the other. The resulting map's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the map and its views. When given a key/value pair that doesn't satisfy the predicate, the map's put() and putAll() methods throw an IllegalArgumentException. Similarly, the map's entries have a Map.Entry.setValue(V) method that throws an IllegalArgumentException when the existing key and the provided value don't satisfy the predicate.
When methods such as removeAll() and clear() are called on the filtered map or its views, only mappings that satisfy the filter will be removed from the underlying map.
The returned map isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered map's methods, such as size(), iterate across every key/value mapping in the underlying map and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered map and use the copy.
Warning: entryPredicate must be consistent with equals, as documented at Predicate.apply(T).
@CheckReturnValue public static <K,V> BiMap<K,V> filterEntries(BiMap<K,V> unfiltered, Predicate<? super Map.Entry<K,V>> entryPredicate)
unfiltered that satisfy a predicate. The returned bimap is a live view of unfiltered; changes to one affect the other. The resulting bimap's keySet(), entrySet(), and values() views have iterators that don't support remove(), but all other methods are supported by the bimap and its views. When given a key/value pair that doesn't satisfy the predicate, the bimap's put(), forcePut() and putAll() methods throw an IllegalArgumentException. Similarly, the map's entries have an Map.Entry.setValue(V) method that throws an IllegalArgumentException when the existing key and the provided value don't satisfy the predicate.
When methods such as removeAll() and clear() are called on the filtered bimap or its views, only mappings that satisfy the filter will be removed from the underlying bimap.
The returned bimap isn't threadsafe or serializable, even if unfiltered is.
Many of the filtered bimap's methods, such as size(), iterate across every key/value mapping in the underlying bimap and determine which satisfy the filter. When a live view is not needed, it may be faster to copy the filtered bimap and use the copy.
Warning: entryPredicate must be consistent with equals , as documented at Predicate.apply(T).
@GwtIncompatible(value="NavigableMap") public static <K,V> NavigableMap<K,V> unmodifiableNavigableMap(NavigableMap<K,V> map)
UnsupportedOperationException. The returned navigable map will be serializable if the specified navigable map is serializable.
map - the navigable map for which an unmodifiable view is to be returned@GwtIncompatible(value="NavigableMap") public static <K,V> NavigableMap<K,V> synchronizedNavigableMap(NavigableMap<K,V> navigableMap)
It is imperative that the user manually synchronize on the returned navigable map when iterating over any of its collection views, or the collections views of any of its descendingMap, subMap, headMap or tailMap views.
NavigableMap<K, V> map = synchronizedNavigableMap(new TreeMap<K, V>()); // Needn't be in synchronized block NavigableSet<K> set = map.navigableKeySet(); synchronized (map) { // Synchronizing on map, not set! Iterator<K> it = set.iterator(); // Must be in synchronized block while (it.hasNext()) { foo(it.next()); } } or:
NavigableMap<K, V> map = synchronizedNavigableMap(new TreeMap<K, V>()); NavigableMap<K, V> map2 = map.subMap(foo, false, bar, true); // Needn't be in synchronized block NavigableSet<K> set2 = map2.descendingKeySet(); synchronized (map) { // Synchronizing on map, not map2 or set2! Iterator<K> it = set2.iterator(); // Must be in synchronized block while (it.hasNext()) { foo(it.next()); } } Failure to follow this advice may result in non-deterministic behavior.
The returned navigable map will be serializable if the specified navigable map is serializable.
navigableMap - the navigable map to be "wrapped" in a synchronized navigable map.Copyright © 2010-2015. All Rights Reserved.