程序包 net.dongliu.commons.collection

类 Maps

java.lang.Object

net.dongliu.commons.collection.Maps

public class Maps
extends java.lang.Object

Utils method for Map

构造器概要

构造器

构造器	说明
Maps()

方法概要

修饰符和类型	方法	说明
static <K,R,V,U> java.util.Map<R,U>	convert(java.util.Map<? extends K,? extends V> map, java.util.function.Function<? super K,? extends R> keyMapper, java.util.function.Function<? super V,? extends U> valueMapper)	Convert map to new immutable map, with key converted by keyMapper, and value converted by valueMapper.
static <K,V,U> java.util.Map<K,U>	convert(java.util.Map<? extends K,? extends V> map, java.util.function.Function<? super V,? extends U> valueMapper)	Convert map to new immutable map, with key not modified, and value converted by function.
static <K,V> java.util.Map<K,V>	filter(java.util.Map<? extends K,? extends V> map, java.util.function.BiPredicate<? super K,? super V> predicate)	Filter map to new immutable map, contains the entries accepted by predicate.
static <T,K,V> java.util.Map<K,V>	from(java.util.Collection<? extends T> elements, java.util.function.Function<? super T,? extends K> keyRetriever, java.util.function.Function<? super T,? extends V> valueMaker)	Create new immutable map from a collection of keys, the values are constructed by valueMaker.
static <K,V> java.util.Map<K,V>	fromKeys(java.util.Collection<? extends K> keys, java.util.function.Function<? super K,? extends V> valueMaker)	Create new immutable map from a collection of keys, the values are constructed by valueMaker.
static <K,V> java.util.Map<K,V>	fromValues(java.util.Collection<? extends V> values, java.util.function.Function<? super V,? extends K> keyRetriever)	Create new immutable map from a collection of values, the values are constructed by keyMaker.
static <K,V> java.util.Map<K,V>	merge(java.util.Map<? extends K,? extends V> map1, java.util.Map<? extends K,? extends V> map2)	Merge tow maps, to a new immutable map, contains key-value in both map.
static <V> java.util.Map<java.lang.String,V>	newCaseInsensitiveMap()	Create a mutable, case insensitive map.
static <V> java.util.Map<java.lang.String,V>	newCaseInsensitiveMap(java.util.Map.Entry<java.lang.String,? extends V>... entries)	Create a mutable, case insensitive map.
static <K,V> java.util.HashMap<K,V>	newHashMap()	Create new HashMap.
static <K,V> java.util.HashMap<K,V>	newHashMap(java.util.Map.Entry<? extends K,? extends V>... entries)	Create new HashMap.
static <K,V,R extends java.util.Map<K,V>> R	newMap(java.util.function.Supplier<R> supplier, java.util.Map.Entry<? extends K,? extends V>... entries)	For easy map creation with initial values.
static <K,V> java.util.Map<K,V>	nullToEmpty(@Nullable java.util.Map<K,V> map)	If map is null, return immutable empty map; else return map self.
static <K,V> java.util.Map<K,V>	of()	Create new immutable empty Map
static <K,V> java.util.Map<K,V>	of(java.util.Map.Entry<? extends K,? extends V> entry)	Create new immutable Map.
static <K,V> java.util.Map<K,V>	of(java.util.Map.Entry<? extends K,? extends V>... entries)	Create new immutable Map.
static <K,V> java.util.Map<K,V>	of(java.util.Map.Entry<? extends K,? extends V> entry1, java.util.Map.Entry<? extends K,? extends V> entry2)	Create new immutable Map.
static <K,V> java.util.Map<K,V>	of(java.util.Map.Entry<? extends K,? extends V> entry1, java.util.Map.Entry<? extends K,? extends V> entry2, java.util.Map.Entry<? extends K,? extends V> entry3)	Create new immutable Map.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

Maps

public Maps()

方法详细资料

nullToEmpty

public static <K,V> java.util.Map<K,V> nullToEmpty(@Nullable java.util.Map<K,V> map)

If map is null, return immutable empty map; else return map self.

参数:

map - the map

返回:

non-null map

newHashMap

public static <K,V> java.util.HashMap<K,V> newHashMap()

Create new HashMap.

newHashMap

@SafeVarargs
public static <K,V> java.util.HashMap<K,V> newHashMap(java.util.Map.Entry<? extends K,? extends V>... entries)

Create new HashMap.

newCaseInsensitiveMap

public static <V> java.util.Map<java.lang.String,V> newCaseInsensitiveMap()

Create a mutable, case insensitive map.

newCaseInsensitiveMap

@SafeVarargs
public static <V> java.util.Map<java.lang.String,V> newCaseInsensitiveMap(java.util.Map.Entry<java.lang.String,? extends V>... entries)

Create a mutable, case insensitive map.

newMap

@SafeVarargs
public static <K,V,R extends java.util.Map<K,V>> R newMap(java.util.function.Supplier<R> supplier,
                                                                            java.util.Map.Entry<? extends K,? extends V>... entries)

For easy map creation with initial values.

类型参数:

K - key type

V - value type

参数:

supplier - the map supplier

entries - the entries to put into map

返回:

the map

of

public static <K,V> java.util.Map<K,V> of()

Create new immutable empty Map

of

public static <K,V> java.util.Map<K,V> of(java.util.Map.Entry<? extends K,? extends V> entry)

Create new immutable Map.

of

public static <K,V> java.util.Map<K,V> of(java.util.Map.Entry<? extends K,? extends V> entry1,
                                                      java.util.Map.Entry<? extends K,? extends V> entry2)

Create new immutable Map.

of

public static <K,V> java.util.Map<K,V> of(java.util.Map.Entry<? extends K,? extends V> entry1,
                                                      java.util.Map.Entry<? extends K,? extends V> entry2,
                                                      java.util.Map.Entry<? extends K,? extends V> entry3)

Create new immutable Map.

of

@SafeVarargs
public static <K,V> java.util.Map<K,V> of(java.util.Map.Entry<? extends K,? extends V>... entries)

Create new immutable Map.

convert

public static <K,R,V,U> java.util.Map<R,U> convert(java.util.Map<? extends K,? extends V> map,
                                                                           java.util.function.Function<? super K,? extends R> keyMapper,
                                                                           java.util.function.Function<? super V,? extends U> valueMapper)

Convert map to new immutable map, with key converted by keyMapper, and value converted by valueMapper.

类型参数:

K - the key type

R - the target key type

V - the original value type

U - the target value type

参数:

map - the original map

valueMapper - the function to convert map value

返回:

new map

convert

public static <K,V,U> java.util.Map<K,U> convert(java.util.Map<? extends K,? extends V> map,
                                                                   java.util.function.Function<? super V,? extends U> valueMapper)

Convert map to new immutable map, with key not modified, and value converted by function.

类型参数:

K - the key type

V - the original value type

U - the target value type

参数:

map - the original map

valueMapper - the function to convert map value

返回:

new map

filter

public static <K,V> java.util.Map<K,V> filter(java.util.Map<? extends K,? extends V> map,
                                                          java.util.function.BiPredicate<? super K,? super V> predicate)

Filter map to new immutable map, contains the entries accepted by predicate.

类型参数:

K - the key type

V - the value type

参数:

map - the origin map

predicate - the predicate to filter map entries

返回:

the new map

merge

public static <K,V> java.util.Map<K,V> merge(java.util.Map<? extends K,? extends V> map1,
                                                         java.util.Map<? extends K,? extends V> map2)

Merge tow maps, to a new immutable map, contains key-value in both map. If map1 and map2 contains the same key, the value from map2 will be used.

类型参数:

K - map key type

V - map value type

参数:

map1 - map1

map2 - map2

返回:

new map

from

public static <T,K,V> java.util.Map<K,V> from(java.util.Collection<? extends T> elements,
                                                                java.util.function.Function<? super T,? extends K> keyRetriever,
                                                                java.util.function.Function<? super T,? extends V> valueMaker)

Create new immutable map from a collection of keys, the values are constructed by valueMaker.

类型参数:

K - key type

V - value type

参数:

elements - the key collections

keyRetriever - to get key from elements

valueMaker - to make value from elements

返回:

new map

fromKeys

public static <K,V> java.util.Map<K,V> fromKeys(java.util.Collection<? extends K> keys,
                                                            java.util.function.Function<? super K,? extends V> valueMaker)

Create new immutable map from a collection of keys, the values are constructed by valueMaker.

类型参数:

K - key type

V - value type

参数:

keys - the key collections

valueMaker - to make value from key

返回:

new map

fromValues

public static <K,V> java.util.Map<K,V> fromValues(java.util.Collection<? extends V> values,
                                                              java.util.function.Function<? super V,? extends K> keyRetriever)

Create new immutable map from a collection of values, the values are constructed by keyMaker.

类型参数:

K - key type

V - value type

参数:

values - the value collections

keyRetriever - to get key from value

返回:

new map