Maps (net.sourceforge.streamsupport:streamsupport 1.6.3 API)

java.lang.Object
- java8.util.Maps

```
public final class Maps
extends Object
```
A place for static default implementations of the new Java 8 default interface methods and static interface methods in the Map interface and, in addition, the JEP 269 "Unmodifiable Map Static Factory Methods" in the Map interface that were introduced in Java 9.
Unmodifiable Maps

The Maps.of, Maps.ofEntries, and Maps.copyOf static factory methods provide a convenient way to create unmodifiable maps. The Map instances created by these methods have the following characteristics:
- They are unmodifiable. Keys and values cannot be added, removed, or updated. Calling any mutator method on the Map will always cause UnsupportedOperationException to be thrown. However, if the contained keys or values are themselves mutable, this may cause the Map to behave inconsistently or its contents to appear to change.
- They disallow null keys and values. Attempts to create them with null keys or values result in NullPointerException.
- They are serializable if all keys and values are serializable.
- They reject duplicate keys at creation time. Duplicate keys passed to a static factory method result in IllegalArgumentException.
- The iteration order of mappings is unspecified and is subject to change.
- They are value-based. Callers should make no assumptions about the identity of the returned instances. Factories are free to create new instances or reuse existing ones. Therefore, identity-sensitive operations on these instances (reference equality ( ==), identity hash code, and synchronization) are unreliable and should be avoided.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Maps.Entry
A place for the static interface methods of the Java 8 Map.Entry interface.

Nested Classes
Modifier and Type	Class and Description
`static class`	`Maps.Entry` A place for the static interface methods of the Java 8 `Map.Entry` interface.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <K,V> V`	`compute(Map<K,V> map, K key, BiFunction<? super K,? super V,? extends V> remappingFunction)` Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping).
`static <K,V> V`	`computeIfAbsent(Map<K,V> map, K key, Function<? super K,? extends V> mappingFunction)` If the specified key is not already associated with a value (or is mapped to `null`), attempts to compute its value using the given mapping function and enters it into the passed `map` unless `null`.
`static <K,V> V`	`computeIfPresent(Map<K,V> map, K key, BiFunction<? super K,? super V,? extends V> remappingFunction)` If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value.
`static <K,V> Map<K,V>`	`copyOf(Map<? extends K,? extends V> map)` Returns an unmodifiable Map containing the entries of the given Map.
`static <K,V> Map.Entry<K,V>`	`entry(K k, V v)` Returns an unmodifiable `Maps.Entry` containing the given key and value.
`static <K,V> void`	`forEach(Map<K,V> map, BiConsumer<? super K,? super V> action)` Performs the given action for each entry in the map until all entries have been processed or the action throws an exception.
`static <K,V> V`	`getOrDefault(Map<K,V> map, Object key, V defaultValue)` Returns the value to which the specified key is mapped, or `defaultValue` if the map contains no mapping for the key.
`static <K,V> V`	`merge(Map<K,V> map, K key, V value, BiFunction<? super V,? super V,? extends V> remappingFunction)` If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value.
`static <K,V> Map<K,V>`	`of()` Returns an unmodifiable map containing zero mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1)` Returns an unmodifiable map containing a single mapping.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2)` Returns an unmodifiable map containing two mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3)` Returns an unmodifiable map containing three mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4)` Returns an unmodifiable map containing four mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5)` Returns an unmodifiable map containing five mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6)` Returns an unmodifiable map containing six mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7)` Returns an unmodifiable map containing seven mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8)` Returns an unmodifiable map containing eight mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8, K k9, V v9)` Returns an unmodifiable map containing nine mappings.
`static <K,V> Map<K,V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8, K k9, V v9, K k10, V v10)` Returns an unmodifiable map containing ten mappings.
`static <K,V> Map<K,V>`	`ofEntries(Map.Entry<? extends K,? extends V>... entries)` Returns an unmodifiable map containing keys and values extracted from the given entries.
`static <K,V> V`	`putIfAbsent(Map<K,V> map, K key, V value)` If the specified key is not already associated with a value (or is mapped to `null`) associates it with the given value and returns `null`, else returns the current value.
`static <K,V> boolean`	`remove(Map<K,V> map, Object key, Object value)` Removes the entry for the specified key only if it is currently mapped to the specified value.
`static <K,V> V`	`replace(Map<K,V> map, K key, V value)` Replaces the entry for the specified key only if it is currently mapped to some value.
`static <K,V> boolean`	`replace(Map<K,V> map, K key, V oldValue, V newValue)` Replaces the entry for the specified key only if currently mapped to the specified value.
`static <K,V> void`	`replaceAll(Map<K,V> map, BiFunction<? super K,? super V,? extends V> function)` Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - putIfAbsent
```
public static <K,V> V putIfAbsent(Map<K,V> map,
                                  K key,
                                  V value)
```
    If the specified key is not already associated with a value (or is mapped to null) associates it with the given value and returns null, else returns the current value.
    Implementation Requirements:
    The default implementation is equivalent to, for the map:
```
 
 V v = map.get(key);
 if (v == null)
     v = map.put(key, value);

 return v;
 
```
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the putIfAbsent operation.
    
    key - key with which the specified value is to be associated
    
    value - value to be associated with the specified key
    
    Returns:
    
    the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)
    
    Throws:
    
    UnsupportedOperationException - if the put operation is not supported by the map (optional)
    
    ClassCastException - if the key or value is of an inappropriate type for the map (optional)
    
    NullPointerException - if the specified key or value is null, and the map does not permit null keys or values (optional)
    
    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in the map (optional)
    
    Since:
    
    1.8
  - getOrDefault
```
public static <K,V> V getOrDefault(Map<K,V> map,
                                   Object key,
                                   V defaultValue)
```
    Returns the value to which the specified key is mapped, or defaultValue if the map contains no mapping for the key.
    Implementation Requirements:
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties.
    
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the getOrDefault operation.
    
    key - the key whose associated value is to be returned
    
    defaultValue - the default mapping of the key
    
    Returns:
    
    the value to which the specified key is mapped, or defaultValue if the map contains no mapping for the key
    
    Throws:
    
    ClassCastException - if the key is of an inappropriate type for the map (optional)
    
    NullPointerException - if the specified key is null and the map does not permit null keys (optional)
    
    Since:
    
    1.8
  - forEach
```
public static <K,V> void forEach(Map<K,V> map,
                                 BiConsumer<? super K,? super V> action)
```
    Performs the given action for each entry in the map until all entries have been processed or the action throws an exception. Unless otherwise specified by the implementing class, actions are performed in the order of entry set iteration (if an iteration order is specified.) Exceptions thrown by the action are relayed to the caller.
    Implementation Requirements:
    The default implementation is equivalent to, for the map:
```
 
 for (Map.Entry<K, V> entry : map.entrySet())
     action.accept(entry.getKey(), entry.getValue());
 
```
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the forEach operation.
    
    action - The action to be performed for each entry
    
    Throws:
    
    NullPointerException - if the specified map or action is null
    
    ConcurrentModificationException - if an entry is found to be removed during iteration
    
    Since:
    
    1.8
  - merge
```
public static <K,V> V merge(Map<K,V> map,
                            K key,
                            V value,
                            BiFunction<? super V,? super V,? extends V> remappingFunction)
```
    If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value. Otherwise, replaces the associated value with the results of the given remapping function, or removes if the result is null. This method may be of use when combining multiple mapped values for a key. For example, to either create or append a String msg to a value mapping:
```
 
 map.merge(key, msg, String::concat)
 
```
    If the remapping function returns null the mapping is removed. If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.
    The remapping function itself should not modify the passed map during computation.
    Implementation Requirements:
    The default implementation is equivalent to performing the following steps for the map, then returning the current value or null if absent:
```
 
 V oldValue = map.get(key);
 V newValue = (oldValue == null) ? value :
              remappingFunction.apply(oldValue, value);
 if (newValue == null)
     map.remove(key);
 else
     map.put(key, newValue);
 
```
    The default implementation makes no guarantees about detecting if the remapping function modifies the passed map during computation and, if appropriate, reporting an error. Non-concurrent implementations should override this method and, on a best-effort basis, throw a ConcurrentModificationException if it is detected that the remapping function modifies the map during computation. Concurrent implementations should override this method and, on a best-effort basis, throw an IllegalStateException if it is detected that the remapping function modifies the map during computation and as a result computation would never complete.
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties. In particular, all implementations of subinterface ConcurrentMap must document whether the remapping function is applied once atomically only if the value is not present.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the merge operation.
    
    key - key with which the resulting value is to be associated
    
    value - the non-null value to be merged with the existing value associated with the key or, if no existing value or a null value is associated with the key, to be associated with the key
    
    remappingFunction - the remapping function to recompute a value if present
    
    Returns:
    
    the new value associated with the specified key, or null if no value is associated with the key
    
    Throws:
    
    UnsupportedOperationException - if the put operation is not supported by the map (optional)
    
    ClassCastException - if the class of the specified key or value prevents it from being stored in the map (optional)
    
    NullPointerException - if the specified key is null and the map does not support null keys or the value or remappingFunction is null
    
    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in the map (optional)
    
    Since:
    
    1.8
  - computeIfAbsent
```
public static <K,V> V computeIfAbsent(Map<K,V> map,
                                      K key,
                                      Function<? super K,? extends V> mappingFunction)
```
    If the specified key is not already associated with a value (or is mapped to null), attempts to compute its value using the given mapping function and enters it into the passed map unless null.
    If the mapping function returns null no mapping is recorded. If the mapping function itself throws an (unchecked) exception, the exception is rethrown, and no mapping is recorded. The most common usage is to construct a new object serving as an initial mapped value or memoized result, as in:
```
 
 map.computeIfAbsent(key, k -> new Value(f(k)));
 
```
    Or to implement a multi-value map, Map<K,Collection<V>>, supporting multiple values per key:
```
 
 map.computeIfAbsent(key, k -> new HashSet<V>()).add(v);
 
```
    The mapping function itself should not modify the passed map during computation.
    Implementation Requirements:
    The default implementation is equivalent to the following steps for the map, then returning the current value or null if now absent:
```
 
 if (map.get(key) == null) {
     V newValue = mappingFunction.apply(key);
     if (newValue != null)
         map.put(key, newValue);
 }
 
```
    The default implementation makes no guarantees about detecting if the mapping function modifies the passed map during computation and, if appropriate, reporting an error. Non-concurrent implementations should override this method and, on a best-effort basis, throw a ConcurrentModificationException if it is detected that the mapping function modifies the map during computation. Concurrent implementations should override this method and, on a best-effort basis, throw an IllegalStateException if it is detected that the mapping function modifies the map during computation and as a result computation would never complete.
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties. In particular, all implementations of subinterface ConcurrentMap must document whether the mapping function is applied once atomically only if the value is not present.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the computeIfAbsent operation.
    
    key - key with which the specified value is to be associated
    
    mappingFunction - the mapping function to compute a value
    
    Returns:
    
    the current (existing or computed) value associated with the specified key, or null if the computed value is null
    
    Throws:
    
    NullPointerException - if the specified key is null and the map does not support null keys, or the mappingFunction is null
    
    UnsupportedOperationException - if the put operation is not supported by the map (optional)
    
    ClassCastException - if the class of the specified key or value prevents it from being stored in the map (optional)
    
    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in the map (optional)
    
    Since:
    
    1.8
  - replace
```
public static <K,V> boolean replace(Map<K,V> map,
                                    K key,
                                    V oldValue,
                                    V newValue)
```
    Replaces the entry for the specified key only if currently mapped to the specified value.
    Implementation Requirements:
    The default implementation is equivalent to, for the map:
```
 
 if (map.containsKey(key) && Objects.equals(map.get(key), value)) {
     map.put(key, newValue);
     return true;
 } else
     return false;
 
```
    The default implementation does not throw NullPointerException for maps that do not support null values if oldValue is null unless newValue is also null.
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the replace operation.
    
    key - key with which the specified value is associated
    
    oldValue - value expected to be associated with the specified key
    
    newValue - value to be associated with the specified key
    
    Returns:
    
    true if the value was replaced
    
    Throws:
    
    UnsupportedOperationException - if the put operation is not supported by the map (optional)
    
    ClassCastException - if the class of a specified key or value prevents it from being stored in the map
    
    NullPointerException - if a specified key or newValue is null, and the map does not permit null keys or values
    
    NullPointerException - if oldValue is null and the map does not permit null values (optional)
    
    IllegalArgumentException - if some property of a specified key or value prevents it from being stored in the map
    
    Since:
    
    1.8
  - replace
```
public static <K,V> V replace(Map<K,V> map,
                              K key,
                              V value)
```
    Replaces the entry for the specified key only if it is currently mapped to some value.
    Implementation Requirements:
    The default implementation is equivalent to, for the map:
```
 
 if (map.containsKey(key)) {
     return map.put(key, value);
 } else
     return null;
 
```
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the replace operation.
    
    key - key with which the specified value is associated
    
    value - value to be associated with the specified key
    
    Returns:
    
    the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)
    
    Throws:
    
    UnsupportedOperationException - if the put operation is not supported by the map (optional)
    
    ClassCastException - if the class of the specified key or value prevents it from being stored in the map (optional)
    
    NullPointerException - if the specified key or value is null, and the map does not permit null keys or values
    
    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in the map
    
    Since:
    
    1.8
  - replaceAll
```
public static <K,V> void replaceAll(Map<K,V> map,
                                    BiFunction<? super K,? super V,? extends V> function)
```
    Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception. Exceptions thrown by the function are relayed to the caller.
    Implementation Requirements:
    
    The default implementation is equivalent to, for the map:
```
 
 for (Map.Entry<K, V> entry : map.entrySet())
     entry.setValue(function.apply(entry.getKey(), entry.getValue()));
 
```
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the replaceAll operation.
    
    function - the function to apply to each entry
    
    Throws:
    
    UnsupportedOperationException - if the set operation is not supported by the map's entry set iterator.
    
    ClassCastException - if the class of a replacement value prevents it from being stored in the map
    
    NullPointerException - if the specified function is null, or the specified replacement value is null, and the map does not permit null values
    
    ClassCastException - if a replacement value is of an inappropriate type for the map (optional)
    
    NullPointerException - if function or a replacement value is null, and the map does not permit null keys or values (optional)
    
    IllegalArgumentException - if some property of a replacement value prevents it from being stored in the map (optional)
    
    ConcurrentModificationException - if an entry is found to be removed during iteration
    
    Since:
    
    1.8
  - compute
```
public static <K,V> V compute(Map<K,V> map,
                              K key,
                              BiFunction<? super K,? super V,? extends V> remappingFunction)
```
    Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping). For example, to either create or append a String msg to a value mapping:
```
 
 map.compute(key, (k, v) -> (v == null) ? msg : v.concat(msg))
```
    (Method merge() is often simpler to use for such purposes.)
    If the remapping function returns null, the mapping is removed (or remains absent if initially absent). If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.
    The remapping function itself should not modify the passed map during computation.
    Implementation Requirements:
    The default implementation is equivalent to performing the following steps for the map, then returning the current value or null if absent:
```
 
 V oldValue = map.get(key);
 V newValue = remappingFunction.apply(key, oldValue);
 if (oldValue != null ) {
    if (newValue != null)
       map.put(key, newValue);
    else
       map.remove(key);
 } else {
    if (newValue != null)
       map.put(key, newValue);
    else
       return null;
 }
 
```
    The default implementation makes no guarantees about detecting if the remapping function modifies the passed map during computation and, if appropriate, reporting an error. Non-concurrent implementations should override this method and, on a best-effort basis, throw a ConcurrentModificationException if it is detected that the remapping function modifies the map during computation. Concurrent implementations should override this method and, on a best-effort basis, throw an IllegalStateException if it is detected that the remapping function modifies the map during computation and as a result computation would never complete.
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties. In particular, all implementations of subinterface ConcurrentMap must document whether the remapping function is applied once atomically only if the value is not present.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the compute operation.
    
    key - key with which the specified value is to be associated
    
    remappingFunction - the remapping function to compute a value
    
    Returns:
    
    the new value associated with the specified key, or null if none
    
    Throws:
    
    NullPointerException - if the specified key is null and the map does not support null keys, or the remappingFunction is null
    
    UnsupportedOperationException - if the put operation is not supported by the map (optional)
    
    ClassCastException - if the class of the specified key or value prevents it from being stored in the map (optional)
    
    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map (optional)
    
    Since:
    
    1.8
  - computeIfPresent
```
public static <K,V> V computeIfPresent(Map<K,V> map,
                                       K key,
                                       BiFunction<? super K,? super V,? extends V> remappingFunction)
```
    If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value.
    If the remapping function returns null, the mapping is removed. If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.
    The remapping function itself should not modify the passed map during computation.
    Implementation Requirements:
    The default implementation is equivalent to performing the following steps for the map, then returning the current value or null if now absent:
```
 
 if (map.get(key) != null) {
     V oldValue = map.get(key);
     V newValue = remappingFunction.apply(key, oldValue);
     if (newValue != null)
         map.put(key, newValue);
     else
         map.remove(key);
 }
 
```
    The default implementation makes no guarantees about detecting if the remapping function modifies the passed map during computation and, if appropriate, reporting an error. Non-concurrent implementations should override this method and, on a best-effort basis, throw a ConcurrentModificationException if it is detected that the remapping function modifies the map during computation. Concurrent implementations should override this method and, on a best-effort basis, throw an IllegalStateException if it is detected that the remapping function modifies the map during computation and as a result computation would never complete.
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties. In particular, all implementations of subinterface ConcurrentMap must document whether the remapping function is applied once atomically only if the value is not present.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the computeIfPresent operation.
    
    key - key with which the specified value is to be associated
    
    remappingFunction - the remapping function to compute a value
    
    Returns:
    
    the new value associated with the specified key, or null if none
    
    Throws:
    
    NullPointerException - if the specified key is null and the map does not support null keys, or the remappingFunction is null
    
    UnsupportedOperationException - if the put operation is not supported by the map (optional)
    
    ClassCastException - if the class of the specified key or value prevents it from being stored in the map (optional)
    
    IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map (optional)
    
    Since:
    
    1.8
  - remove
```
public static <K,V> boolean remove(Map<K,V> map,
                                   Object key,
                                   Object value)
```
    Removes the entry for the specified key only if it is currently mapped to the specified value.
    Implementation Requirements:
    The default implementation is equivalent to, for the map:
```
 
 if (map.containsKey(key) && Objects.equals(map.get(key), value)) {
     map.remove(key);
     return true;
 } else
     return false;
 
```
    The default implementation makes no guarantees about synchronization or atomicity properties of this method. Any implementation providing atomicity guarantees must override this method and document its concurrency properties.
    Type Parameters:
    
    K - the type of keys maintained by the passed map
    
    V - the type of mapped values in the passed map
    
    Parameters:
    
    map - the Map on which to execute the remove operation.
    
    key - key with which the specified value is associated
    
    value - value expected to be associated with the specified key
    
    Returns:
    
    true if the value was removed
    
    Throws:
    
    UnsupportedOperationException - if the remove operation is not supported by the map (optional)
    
    ClassCastException - if the key or value is of an inappropriate type for the map (optional)
    
    NullPointerException - if the specified key or value is null, and the map does not permit null keys or values (optional)
    
    Since:
    
    1.8
  - of
```
public static <K,V> Map<K,V> of()
```
    Returns an unmodifiable map containing zero mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Returns:
    
    an empty Map
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1)
```
    Returns an unmodifiable map containing a single mapping. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the mapping's key
    
    v1 - the mapping's value
    
    Returns:
    
    a Map containing the specified mapping
    
    Throws:
    
    NullPointerException - if the key or the value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2)
```
    Returns an unmodifiable map containing two mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if the keys are duplicates
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3)
```
    Returns an unmodifiable map containing three mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3,
                                K k4,
                                V v4)
```
    Returns an unmodifiable map containing four mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    k4 - the fourth mapping's key
    
    v4 - the fourth mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3,
                                K k4,
                                V v4,
                                K k5,
                                V v5)
```
    Returns an unmodifiable map containing five mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    k4 - the fourth mapping's key
    
    v4 - the fourth mapping's value
    
    k5 - the fifth mapping's key
    
    v5 - the fifth mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3,
                                K k4,
                                V v4,
                                K k5,
                                V v5,
                                K k6,
                                V v6)
```
    Returns an unmodifiable map containing six mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    k4 - the fourth mapping's key
    
    v4 - the fourth mapping's value
    
    k5 - the fifth mapping's key
    
    v5 - the fifth mapping's value
    
    k6 - the sixth mapping's key
    
    v6 - the sixth mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3,
                                K k4,
                                V v4,
                                K k5,
                                V v5,
                                K k6,
                                V v6,
                                K k7,
                                V v7)
```
    Returns an unmodifiable map containing seven mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    k4 - the fourth mapping's key
    
    v4 - the fourth mapping's value
    
    k5 - the fifth mapping's key
    
    v5 - the fifth mapping's value
    
    k6 - the sixth mapping's key
    
    v6 - the sixth mapping's value
    
    k7 - the seventh mapping's key
    
    v7 - the seventh mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3,
                                K k4,
                                V v4,
                                K k5,
                                V v5,
                                K k6,
                                V v6,
                                K k7,
                                V v7,
                                K k8,
                                V v8)
```
    Returns an unmodifiable map containing eight mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    k4 - the fourth mapping's key
    
    v4 - the fourth mapping's value
    
    k5 - the fifth mapping's key
    
    v5 - the fifth mapping's value
    
    k6 - the sixth mapping's key
    
    v6 - the sixth mapping's value
    
    k7 - the seventh mapping's key
    
    v7 - the seventh mapping's value
    
    k8 - the eighth mapping's key
    
    v8 - the eighth mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3,
                                K k4,
                                V v4,
                                K k5,
                                V v5,
                                K k6,
                                V v6,
                                K k7,
                                V v7,
                                K k8,
                                V v8,
                                K k9,
                                V v9)
```
    Returns an unmodifiable map containing nine mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    k4 - the fourth mapping's key
    
    v4 - the fourth mapping's value
    
    k5 - the fifth mapping's key
    
    v5 - the fifth mapping's value
    
    k6 - the sixth mapping's key
    
    v6 - the sixth mapping's value
    
    k7 - the seventh mapping's key
    
    v7 - the seventh mapping's value
    
    k8 - the eighth mapping's key
    
    v8 - the eighth mapping's value
    
    k9 - the ninth mapping's key
    
    v9 - the ninth mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - of
```
public static <K,V> Map<K,V> of(K k1,
                                V v1,
                                K k2,
                                V v2,
                                K k3,
                                V v3,
                                K k4,
                                V v4,
                                K k5,
                                V v5,
                                K k6,
                                V v6,
                                K k7,
                                V v7,
                                K k8,
                                V v8,
                                K k9,
                                V v9,
                                K k10,
                                V v10)
```
    Returns an unmodifiable map containing ten mappings. See Unmodifiable Maps for details.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    k1 - the first mapping's key
    
    v1 - the first mapping's value
    
    k2 - the second mapping's key
    
    v2 - the second mapping's value
    
    k3 - the third mapping's key
    
    v3 - the third mapping's value
    
    k4 - the fourth mapping's key
    
    v4 - the fourth mapping's value
    
    k5 - the fifth mapping's key
    
    v5 - the fifth mapping's value
    
    k6 - the sixth mapping's key
    
    v6 - the sixth mapping's value
    
    k7 - the seventh mapping's key
    
    v7 - the seventh mapping's value
    
    k8 - the eighth mapping's key
    
    v8 - the eighth mapping's value
    
    k9 - the ninth mapping's key
    
    v9 - the ninth mapping's value
    
    k10 - the tenth mapping's key
    
    v10 - the tenth mapping's value
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any key or value is null
    
    Since:
    
    9
  - ofEntries
```
public static <K,V> Map<K,V> ofEntries(Map.Entry<? extends K,? extends V>... entries)
```
    Returns an unmodifiable map containing keys and values extracted from the given entries. The entries themselves are not stored in the map. See Unmodifiable Maps for details.
    API Note:
    It is convenient to create the map entries using the Maps.entry() method. For example,
```
 
     import static java.util.Maps.entry;

     Map<Integer,String> map = Maps.ofEntries(
         entry(1, "a"),
         entry(2, "b"),
         entry(3, "c"),
         ...
         entry(26, "z"));
 
```
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    entries - Map.Entrys containing the keys and values from which the map is populated
    
    Returns:
    
    a Map containing the specified mappings
    
    Throws:
    
    IllegalArgumentException - if there are any duplicate keys
    
    NullPointerException - if any entry, key, or value is null, or if the entries array is null
    
    Since:
    
    9
    
    See Also:
    
    Maps.entry()
  - entry
```
public static <K,V> Map.Entry<K,V> entry(K k,
                                         V v)
```
    Returns an unmodifiable Maps.Entry containing the given key and value. These entries are suitable for populating Map instances using the Maps.ofEntries() method. The Entry instances created by this method have the following characteristics:
    - They disallow null keys and values. Attempts to create them using a null key or value result in NullPointerException.
    - They are unmodifiable. Calls to Entry.setValue() on a returned Entry result in UnsupportedOperationException.
    - They are not serializable.
    - They are value-based. Callers should make no assumptions about the identity of the returned instances. This method is free to create new instances or reuse existing ones. Therefore, identity-sensitive operations on these instances (reference equality (==), identity hash code, and synchronization) are unreliable and should be avoided.
    API Note:
    For a serializable Entry, see AbstractMap.SimpleEntry or AbstractMap.SimpleImmutableEntry.
    Type Parameters:
    
    K - the key's type
    
    V - the value's type
    
    Parameters:
    
    k - the key
    
    v - the value
    
    Returns:
    
    an Entry containing the specified key and value
    
    Throws:
    
    NullPointerException - if the key or value is null
    
    Since:
    
    9
    
    See Also:
    
    Maps.ofEntries()
  - copyOf
```
public static <K,V> Map<K,V> copyOf(Map<? extends K,? extends V> map)
```
    Returns an unmodifiable Map containing the entries of the given Map. The given Map must not be null, and it must not contain any null keys or values. If the given Map is subsequently modified, the returned Map will not reflect such modifications.
    Implementation Note: If the given Map is an unmodifiable Map, calling copyOf will generally not create a copy.
    
    Type Parameters:
    
    K - the Map's key type
    
    V - the Map's value type
    
    Parameters:
    
    map - the map from which entries are drawn, must be non-null
    
    Returns:
    
    a Map containing the entries of the given Map
    
    Throws:
    
    NullPointerException - if map is null, or if it contains any null keys or values
    
    Since:
    
    10

Class Maps

Unmodifiable Maps

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

putIfAbsent

getOrDefault

forEach

merge

computeIfAbsent

replace

replace

replaceAll

compute

computeIfPresent

remove

of

of

of

of

of

of

of

of

of

of

of

ofEntries

entry

copyOf