public
class
Maps
extends Object| java.lang.Object | |
| ↳ | com.pnfsoftware.jeb.util.collect.Maps |
Class Overview
Utility methods for Map maps.
Summary
| Public Constructors | |||||||||||
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| Maps() | |||||||||||
| Public Methods | |||||||||||
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| static <K, V> List<V> |
addMulti(Map<K, List<V>> map, K key)
Add a list bucket for the key in the provided multi-map.
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| static <K, V, C extends Collection<V>> Collection<V> |
collectMulti(Map<K, C> map)
Collect the values of a multi-map.
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| static <K, V extends Comparable<V>> LinkedHashMap<K, V> |
createSortedMapByValue(Map<K, V> map, boolean ascending)
Sort a map by its values.
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| static <K, V> V |
get(Map<K, V> map, K key)
Get a value from a potentially null map.
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| static <K, V> V |
get(Map<K, V> map, K key, V safeValue)
Get a value from a potentially null map.
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| static <K, V extends Comparable<V>> List<Entry<K, V>> |
getSortedEntriesByValue(Map<K, V> map, boolean descending)
Retrieve a list of sorted (key,value) pairs from the provided map, sorted by values.
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| static <K, V extends Comparable<V>> List<Entry<K, V>> |
getSortedEntriesByValue(Map<K, V> map)
Retrieve a list of sorted (key,value) pairs from the provided map, sorted by ascending
values.
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| static <K, V extends Comparable<V>> List<V> |
getSortedValues(Map<K, V> map, boolean ascending)
Retrieve the values of a map, sorted by natural ascending or descending order.
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| static <K, V extends Comparable<V>> List<V> |
getSortedValues(Map<K, V> map)
Retrieve the values of a map, sorted by natural ascending.
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| static <K, V, C extends Collection<V>> boolean |
putMulti(Map<K, C> map, K key, V value, Supplier<C> supplier)
Add a key-value entry to the provided multi-map.
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| static <K, V> List<V> |
putMulti(Map<K, List<V>> map, K key, V value)
Add a key-value entry to the provided multi-map.
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| static <K, V> List<V> |
putMulti(Map<K, List<V>> map, K key, Collection<V> values)
Add a collection of key-value entries to the provided multi-map.
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| static <V> String |
putNoOverwrite(Map<String, V> map, String preferredKey, V value)
Insert a value to a string-key'ed map with guarantee that no existing key-value pair will be
overwritten.
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| static <K> boolean | removeAll(Map<K, ?> map, Collection<? extends K> keys) | ||||||||||
| static <K, V> int |
removeForValue(Map<K, V> map, V v, boolean useReferenceEquality)
Remove entries that map to the provided value.
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| static <K, V, C extends Collection<V>> boolean |
removeMulti(Map<K, C> map, K key, V value)
Remove a key-value stored in a multi-map.
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| static <K> boolean | retainAll(Map<K, ?> map, Collection<? extends K> keys) | ||||||||||
| static <K, V> HashMap<K, V> |
toMap(K key, V value, K key2, V value2, K key3, V value3)
Build a HashMap containing 3 elements (key, value).
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| static <K, V> HashMap<K, V> |
toMap(K key, V value, K key2, V value2)
Build a HashMap containing 2 elements (key, value).
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| static <K, V> HashMap<K, V> |
toMap(K key, V value)
Build a HashMap containing 1 element (key, value).
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| static <K, V> Map<K, V> |
toMap(K key, V value, Class<? extends Map> c)
Build a map containing 1 element (key, value).
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[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
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Public Constructors
public Maps ()
Public Methods
public static List<V> addMulti (Map<K, List<V>> map, K key)
Add a list bucket for the key in the provided multi-map. If no list of values exists for the
key, a new ArrayList is created with an initial capacity of one.
public static Collection<V> collectMulti (Map<K, C> map)
Collect the values of a multi-map.
Parameters
| map | a map of key-collections |
|---|
Returns
- the collection of values stored in the multi-map
public static LinkedHashMap<K, V> createSortedMapByValue (Map<K, V> map, boolean ascending)
Sort a map by its values. The values must be Comparable objects.
Parameters
| map | a map; it must not contain null values |
|---|---|
| ascending | true to sort by ascending order, false to sort by descending order |
Returns
- a map ordered by its values; this map can be modified without impacting the original map's structure
public static V get (Map<K, V> map, K key)
Get a value from a potentially null map.
Parameters
| map | optional map |
|---|---|
| key | key |
Returns
- the value, null if the map is null or contains a key pointing to a null value
public static V get (Map<K, V> map, K key, V safeValue)
Get a value from a potentially null map.
Parameters
| map | optional map |
|---|---|
| key | key |
| safeValue | value returned if the map is null or does not contain the provided key |
Returns
- the value - note: the returned value can be null if the key is present, but points to a null value
public static List<Entry<K, V>> getSortedEntriesByValue (Map<K, V> map, boolean descending)
Retrieve a list of sorted (key,value) pairs from the provided map, sorted by values.
Parameters
| map | the input map (should not contain null values) |
|---|---|
| descending | if true, the list is sorted by descending values instead of ascending values |
public static List<Entry<K, V>> getSortedEntriesByValue (Map<K, V> map)
Retrieve a list of sorted (key,value) pairs from the provided map, sorted by ascending values.
Parameters
| map | the input map (preferably not containing null values) |
|---|
public static List<V> getSortedValues (Map<K, V> map, boolean ascending)
Retrieve the values of a map, sorted by natural ascending or descending order. The values must be Comparable objects.
Parameters
| map | a map; it must not contain null values |
|---|---|
| ascending | true to sort by ascending order, false to sort by descending order |
Returns
- a list of sorted values; the list can be modified without impacting the map's structure
public static List<V> getSortedValues (Map<K, V> map)
Retrieve the values of a map, sorted by natural ascending. The values must be Comparable objects.
Parameters
| map | a map; it must not contain null values |
|---|
Returns
- a list of sorted values; the list can be modified without impacting the map's structure
public static boolean putMulti (Map<K, C> map, K key, V value, Supplier<C> supplier)
Add a key-value entry to the provided multi-map. If no list of values exists for the key, a new list is created using the provided listFactory parameter.
Parameters
| map | the map |
|---|---|
| key | the key |
| value | value to be added to the collection mapped for key |
| supplier | collection factory if no collection exists and is mapped for the provided key |
Returns
- true if the collection to which the value was added changed (i.e., same semantic as
add(Object))
public static List<V> putMulti (Map<K, List<V>> map, K key, V value)
Add a key-value entry to the provided multi-map. If no list of values exists for the key, a
new ArrayList is created with an initial capacity of one (to accommodate the addition
of the value).
Equivalent to putMulti(Map, Object, Object, Supplier) with supplier being
ArrayList::new.
Returns
- the list for the provided key
public static List<V> putMulti (Map<K, List<V>> map, K key, Collection<V> values)
Add a collection of key-value entries to the provided multi-map. If no list of values exists
for the key, a new ArrayList is created.
public static String putNoOverwrite (Map<String, V> map, String preferredKey, V value)
Insert a value to a string-key'ed map with guarantee that no existing key-value pair will be overwritten.
Parameters
| preferredKey | the preferred key for insertion |
|---|
Returns
- the actual key that was generated for insertion (may be different than the Preferred if using the preferred would lead to an existing mapping to be overwritten)
public static boolean removeAll (Map<K, ?> map, Collection<? extends K> keys)
public static int removeForValue (Map<K, V> map, V v, boolean useReferenceEquality)
Remove entries that map to the provided value.
Parameters
| map | map |
|---|---|
| v | a non-null value |
| useReferenceEquality | if true, values are compared using ==; else, they are compared using equals() |
Returns
- the number of entries removed
public static boolean removeMulti (Map<K, C> map, K key, V value)
Remove a key-value stored in a multi-map.
Parameters
| map | a map of key-collections |
|---|
Returns
- true if a key-value was removed, false otherwise
public static boolean retainAll (Map<K, ?> map, Collection<? extends K> keys)
public static HashMap<K, V> toMap (K key, V value, K key2, V value2, K key3, V value3)
Build a HashMap containing 3 elements (key, value).
Parameters
| key | key |
|---|---|
| value | value associated to key |
| key2 | 2nd key |
| value2 | value associated to 2nd key |
| key3 | 3rd key |
| value3 | value associated to 3rd key |
public static HashMap<K, V> toMap (K key, V value, K key2, V value2)
Build a HashMap containing 2 elements (key, value).
Parameters
| key | key |
|---|---|
| value | value associated to key |
| key2 | 2nd key |
| value2 | value associated to 2nd key |
public static HashMap<K, V> toMap (K key, V value)
Build a HashMap containing 1 element (key, value).
Parameters
| key | key |
|---|---|
| value | value associated to key |
public static Map<K, V> toMap (K key, V value, Class<? extends Map> c)
Build a map containing 1 element (key, value).
Parameters
| key | key |
|---|---|
| value | value associated to key |
| c | optional requested map type; use null to obtain a HashMap |