Package org.apache.jackrabbit.oak.commons.collections

Class MapUtils

java.lang.Object

org.apache.jackrabbit.oak.commons.collections.MapUtils

public class MapUtils
extends Object

Utility methods for Map conversions.

Method Summary

Modifier and Type	Method	Description
static <K,V> @NotNull Map<K,V>	filterEntries(@NotNull Map<K,V> map, @NotNull Predicate<? super Map.Entry<K,V>> predicate)	Create a new Map after filtering the entries of the given map based on the specified predicate applied to the Map.Entry.
static <K,V> @NotNull Map<K,V>	filterKeys(@NotNull Map<K,V> map, @NotNull Predicate<? super K> predicate)	Create a new Map after filtering the entries of the given map based on the specified predicate applied to the keys.
static <K,V> @NotNull Map<K,V>	filterValues(@NotNull Map<K,V> map, @NotNull Predicate<? super V> predicate)	Create a new Map after filtering the entries of the given map based on the specified predicate applied to the values.
static @NotNull Map<String,String>	fromProperties(@NotNull Properties properties)	Converts a Properties object to an unmodifiable Map with string keys and values.
static <K,V> @NotNull Map<K,V>	newHashMap(int capacity)	Creates a new, empty HashMap with expected capacity.

Methods inherited from class java.lang.Object

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

Method Detail

newHashMap

@NotNull
public static <K,V> @NotNull Map<K,V> newHashMap(int capacity)

Creates a new, empty HashMap with expected capacity.

The returned map uses the default load factor of 0.75, and its capacity is large enough to add expected number of elements without resizing.

Parameters:

capacity - the expected number of elements

Throws:

IllegalArgumentException - if capacity is negative

See Also:

SetUtils.newHashSet(int), SetUtils.newLinkedHashSet(int)

fromProperties

@NotNull
public static @NotNull Map<String,String> fromProperties(@NotNull
                                                               @NotNull Properties properties)

Converts a Properties object to an unmodifiable Map with string keys and values.

Parameters:

properties - the Properties object to convert, must not be null

Returns:

an unmodifiable Map containing the same entries as the given Properties object

Throws:

NullPointerException - if the properties parameter is null

filterKeys

@NotNull
public static <K,V> @NotNull Map<K,V> filterKeys(@NotNull
                                                             @NotNull Map<K,V> map,
                                                             @NotNull
                                                             @NotNull Predicate<? super K> predicate)

Create a new Map after filtering the entries of the given map based on the specified predicate applied to the keys.

Type Parameters:

K - the type of keys in the map

V - the type of values in the map

Parameters:

map - the map to filter, must not be null

predicate - the predicate to apply to the keys, must not be null

Returns:

a new map containing only the entries whose keys match the predicate

Throws:

NullPointerException - if the map or predicate is null

See Also:

filterValues(Map, Predicate), filterEntries(Map, Predicate)

filterValues

@NotNull
public static <K,V> @NotNull Map<K,V> filterValues(@NotNull
                                                               @NotNull Map<K,V> map,
                                                               @NotNull
                                                               @NotNull Predicate<? super V> predicate)

Create a new Map after filtering the entries of the given map based on the specified predicate applied to the values.

Type Parameters:

K - the type of keys in the map

V - the type of values in the map

Parameters:

map - the map to filter, must not be null

predicate - the predicate to apply to the values, must not be null

Returns:

a new map containing only the entries whose values match the predicate

Throws:

NullPointerException - if the map or predicate is null

See Also:

filterKeys(Map, Predicate), filterEntries(Map, Predicate)

filterEntries

@NotNull
public static <K,V> @NotNull Map<K,V> filterEntries(@NotNull
                                                                @NotNull Map<K,V> map,
                                                                @NotNull
                                                                @NotNull Predicate<? super Map.Entry<K,V>> predicate)

Create a new Map after filtering the entries of the given map based on the specified predicate applied to the Map.Entry.

Type Parameters:

K - the type of keys in the map

V - the type of values in the map

Parameters:

map - the map to filter, must not be null

predicate - the predicate to apply to the Map.Entry, must not be null

Returns:

a new map containing only the entries whose values match the predicate

Throws:

NullPointerException - if the map or predicate is null

See Also:

filterKeys(Map, Predicate), filterValues(Map, Predicate)