org.apache.commons.collections

Class MapUtils

java.lang.Object

org.apache.commons.collections.MapUtils

public class MapUtils
extends java.lang.Object

Provides utility methods and decorators for Map and SortedMap instances.

It contains various type safe methods as well as other useful features like deep copying.

It also provides the following decorators:

• fixedSizeMap(Map)
• fixedSizeSortedMap(SortedMap)
• lazyMap(Map,Factory)
• lazyMap(Map,Transformer)
• lazySortedMap(SortedMap,Factory)
• lazySortedMap(SortedMap,Transformer)
• predicatedMap(Map,Predicate,Predicate)
• predicatedSortedMap(SortedMap,Predicate,Predicate)
• transformedMap(Map, Transformer, Transformer)
• transformedSortedMap(SortedMap, Transformer, Transformer)
• typedMap(Map, Class, Class)
• typedSortedMap(SortedMap, Class, Class)
• multiValueMap( Map )
• multiValueMap( Map, Class )
• multiValueMap( Map, Factory )

Since:

Commons Collections 1.0

Field Summary

Fields

Modifier and Type	Field and Description
static java.util.Map	EMPTY_MAP An empty unmodifiable map.
static java.util.SortedMap	EMPTY_SORTED_MAP An empty unmodifiable sorted map.

Constructor Summary

Constructors

Constructor and Description
MapUtils() MapUtils should not normally be instantiated.

Method Summary

Modifier and Type	Method and Description
static void	debugPrint(java.io.PrintStream out, java.lang.Object label, java.util.Map map) Prints the given map with nice line breaks.
static java.util.Map	fixedSizeMap(java.util.Map map) Returns a fixed-sized map backed by the given map.
static java.util.SortedMap	fixedSizeSortedMap(java.util.SortedMap map) Returns a fixed-sized sorted map backed by the given sorted map.
static java.lang.Boolean	getBoolean(java.util.Map map, java.lang.Object key) Gets a Boolean from a Map in a null-safe manner.
static java.lang.Boolean	getBoolean(java.util.Map map, java.lang.Object key, java.lang.Boolean defaultValue) Looks up the given key in the given map, converting the result into a boolean, using the default value if the the conversion fails.
static boolean	getBooleanValue(java.util.Map map, java.lang.Object key) Gets a boolean from a Map in a null-safe manner.
static boolean	getBooleanValue(java.util.Map map, java.lang.Object key, boolean defaultValue) Gets a boolean from a Map in a null-safe manner, using the default value if the the conversion fails.
static java.lang.Byte	getByte(java.util.Map map, java.lang.Object key) Gets a Byte from a Map in a null-safe manner.
static java.lang.Byte	getByte(java.util.Map map, java.lang.Object key, java.lang.Byte defaultValue) Looks up the given key in the given map, converting the result into a byte, using the default value if the the conversion fails.
static byte	getByteValue(java.util.Map map, java.lang.Object key) Gets a byte from a Map in a null-safe manner.
static byte	getByteValue(java.util.Map map, java.lang.Object key, byte defaultValue) Gets a byte from a Map in a null-safe manner, using the default value if the the conversion fails.
static java.lang.Double	getDouble(java.util.Map map, java.lang.Object key) Gets a Double from a Map in a null-safe manner.
static java.lang.Double	getDouble(java.util.Map map, java.lang.Object key, java.lang.Double defaultValue) Looks up the given key in the given map, converting the result into a double, using the default value if the the conversion fails.
static double	getDoubleValue(java.util.Map map, java.lang.Object key) Gets a double from a Map in a null-safe manner.
static double	getDoubleValue(java.util.Map map, java.lang.Object key, double defaultValue) Gets a double from a Map in a null-safe manner, using the default value if the the conversion fails.
static java.lang.Float	getFloat(java.util.Map map, java.lang.Object key) Gets a Float from a Map in a null-safe manner.
static java.lang.Float	getFloat(java.util.Map map, java.lang.Object key, java.lang.Float defaultValue) Looks up the given key in the given map, converting the result into a float, using the default value if the the conversion fails.
static float	getFloatValue(java.util.Map map, java.lang.Object key) Gets a float from a Map in a null-safe manner.
static float	getFloatValue(java.util.Map map, java.lang.Object key, float defaultValue) Gets a float from a Map in a null-safe manner, using the default value if the the conversion fails.
static java.lang.Integer	getInteger(java.util.Map map, java.lang.Object key) Gets a Integer from a Map in a null-safe manner.
static java.lang.Integer	getInteger(java.util.Map map, java.lang.Object key, java.lang.Integer defaultValue) Looks up the given key in the given map, converting the result into an integer, using the default value if the the conversion fails.
static int	getIntValue(java.util.Map map, java.lang.Object key) Gets an int from a Map in a null-safe manner.
static int	getIntValue(java.util.Map map, java.lang.Object key, int defaultValue) Gets an int from a Map in a null-safe manner, using the default value if the the conversion fails.
static java.lang.Long	getLong(java.util.Map map, java.lang.Object key) Gets a Long from a Map in a null-safe manner.
static java.lang.Long	getLong(java.util.Map map, java.lang.Object key, java.lang.Long defaultValue) Looks up the given key in the given map, converting the result into a long, using the default value if the the conversion fails.
static long	getLongValue(java.util.Map map, java.lang.Object key) Gets a long from a Map in a null-safe manner.
static long	getLongValue(java.util.Map map, java.lang.Object key, long defaultValue) Gets a long from a Map in a null-safe manner, using the default value if the the conversion fails.
static java.util.Map	getMap(java.util.Map map, java.lang.Object key) Gets a Map from a Map in a null-safe manner.
static java.util.Map	getMap(java.util.Map map, java.lang.Object key, java.util.Map defaultValue) Looks up the given key in the given map, converting the result into a map, using the default value if the the conversion fails.
static java.lang.Number	getNumber(java.util.Map map, java.lang.Object key) Gets a Number from a Map in a null-safe manner.
static java.lang.Number	getNumber(java.util.Map map, java.lang.Object key, java.lang.Number defaultValue) Looks up the given key in the given map, converting the result into a number, using the default value if the the conversion fails.
static java.lang.Object	getObject(java.util.Map map, java.lang.Object key) Gets from a Map in a null-safe manner.
static java.lang.Object	getObject(java.util.Map map, java.lang.Object key, java.lang.Object defaultValue) Looks up the given key in the given map, converting null into the given default value.
static java.lang.Short	getShort(java.util.Map map, java.lang.Object key) Gets a Short from a Map in a null-safe manner.
static java.lang.Short	getShort(java.util.Map map, java.lang.Object key, java.lang.Short defaultValue) Looks up the given key in the given map, converting the result into a short, using the default value if the the conversion fails.
static short	getShortValue(java.util.Map map, java.lang.Object key) Gets a short from a Map in a null-safe manner.
static short	getShortValue(java.util.Map map, java.lang.Object key, short defaultValue) Gets a short from a Map in a null-safe manner, using the default value if the the conversion fails.
static java.lang.String	getString(java.util.Map map, java.lang.Object key) Gets a String from a Map in a null-safe manner.
static java.lang.String	getString(java.util.Map map, java.lang.Object key, java.lang.String defaultValue) Looks up the given key in the given map, converting the result into a string, using the default value if the the conversion fails.
static java.util.Map	invertMap(java.util.Map map) Inverts the supplied map returning a new HashMap such that the keys of the input are swapped with the values.
static boolean	isEmpty(java.util.Map map) Null-safe check if the specified map is empty.
static boolean	isNotEmpty(java.util.Map map) Null-safe check if the specified map is not empty.
static java.util.Map	lazyMap(java.util.Map map, Factory factory) Returns a "lazy" map whose values will be created on demand.
static java.util.Map	lazyMap(java.util.Map map, Transformer transformerFactory) Returns a "lazy" map whose values will be created on demand.
static java.util.SortedMap	lazySortedMap(java.util.SortedMap map, Factory factory) Returns a "lazy" sorted map whose values will be created on demand.
static java.util.SortedMap	lazySortedMap(java.util.SortedMap map, Transformer transformerFactory) Returns a "lazy" sorted map whose values will be created on demand.
static java.util.Map	multiValueMap(java.util.Map map) Creates a mult-value map backed by the given map which returns collections of type ArrayList.
static java.util.Map	multiValueMap(java.util.Map map, java.lang.Class collectionClass) Creates a multi-value map backed by the given map which returns collections of the specified type.
static java.util.Map	multiValueMap(java.util.Map map, Factory collectionFactory) Creates a multi-value map backed by the given map which returns collections created by the specified collection factory.
static java.util.Map	orderedMap(java.util.Map map) Returns a map that maintains the order of keys that are added backed by the given map.
static java.util.Map	predicatedMap(java.util.Map map, Predicate keyPred, Predicate valuePred) Returns a predicated (validating) map backed by the given map.
static java.util.SortedMap	predicatedSortedMap(java.util.SortedMap map, Predicate keyPred, Predicate valuePred) Returns a predicated (validating) sorted map backed by the given map.
static java.util.Map	putAll(java.util.Map map, java.lang.Object[] array) Puts all the keys and values from the specified array into the map.
static void	safeAddToMap(java.util.Map map, java.lang.Object key, java.lang.Object value) Protects against adding null values to a map.
static java.util.Map	synchronizedMap(java.util.Map map) Returns a synchronized map backed by the given map.
static java.util.Map	synchronizedSortedMap(java.util.SortedMap map) Returns a synchronized sorted map backed by the given sorted map.
static java.util.Map	toMap(java.util.ResourceBundle resourceBundle) Creates a new HashMap using data copied from a ResourceBundle.
static java.util.Properties	toProperties(java.util.Map map) Gets a new Properties object initialised with the values from a Map.
static java.util.Map	transformedMap(java.util.Map map, Transformer keyTransformer, Transformer valueTransformer) Returns a transformed map backed by the given map.
static java.util.SortedMap	transformedSortedMap(java.util.SortedMap map, Transformer keyTransformer, Transformer valueTransformer) Returns a transformed sorted map backed by the given map.
static java.util.Map	typedMap(java.util.Map map, java.lang.Class keyType, java.lang.Class valueType) Returns a typed map backed by the given map.
static java.util.SortedMap	typedSortedMap(java.util.SortedMap map, java.lang.Class keyType, java.lang.Class valueType) Returns a typed sorted map backed by the given map.
static java.util.Map	unmodifiableMap(java.util.Map map) Returns an unmodifiable map backed by the given map.
static java.util.Map	unmodifiableSortedMap(java.util.SortedMap map) Returns an unmodifiable sorted map backed by the given sorted map.
static void	verbosePrint(java.io.PrintStream out, java.lang.Object label, java.util.Map map) Prints the given map with nice line breaks.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_MAP

public static final java.util.Map EMPTY_MAP

An empty unmodifiable map. This was not provided in JDK1.2.

EMPTY_SORTED_MAP

public static final java.util.SortedMap EMPTY_SORTED_MAP

An empty unmodifiable sorted map. This is not provided in the JDK.

Constructor Detail

MapUtils

public MapUtils()

MapUtils should not normally be instantiated.

Method Detail

getObject

public static java.lang.Object getObject(java.util.Map map,
                                         java.lang.Object key)

Gets from a Map in a null-safe manner.

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map, null if null map input

getString

public static java.lang.String getString(java.util.Map map,
                                         java.lang.Object key)

Gets a String from a Map in a null-safe manner.

The String is obtained via toString.

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a String, null if null map input

getBoolean

public static java.lang.Boolean getBoolean(java.util.Map map,
                                           java.lang.Object key)

Gets a Boolean from a Map in a null-safe manner.

If the value is a Boolean it is returned directly. If the value is a String and it equals 'true' ignoring case then true is returned, otherwise false. If the value is a Number an integer zero value returns false and non-zero returns true. Otherwise, null is returned.

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Boolean, null if null map input

getNumber

public static java.lang.Number getNumber(java.util.Map map,
                                         java.lang.Object key)

Gets a Number from a Map in a null-safe manner.

If the value is a Number it is returned directly. If the value is a String it is converted using NumberFormat.parse(String) on the system default formatter returning null if the conversion fails. Otherwise, null is returned.

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Number, null if null map input

getByte

public static java.lang.Byte getByte(java.util.Map map,
                                     java.lang.Object key)

Gets a Byte from a Map in a null-safe manner.

The Byte is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Byte, null if null map input

getShort

public static java.lang.Short getShort(java.util.Map map,
                                       java.lang.Object key)

Gets a Short from a Map in a null-safe manner.

The Short is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Short, null if null map input

getInteger

public static java.lang.Integer getInteger(java.util.Map map,
                                           java.lang.Object key)

Gets a Integer from a Map in a null-safe manner.

The Integer is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Integer, null if null map input

getLong

public static java.lang.Long getLong(java.util.Map map,
                                     java.lang.Object key)

Gets a Long from a Map in a null-safe manner.

The Long is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Long, null if null map input

getFloat

public static java.lang.Float getFloat(java.util.Map map,
                                       java.lang.Object key)

Gets a Float from a Map in a null-safe manner.

The Float is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Float, null if null map input

getDouble

public static java.lang.Double getDouble(java.util.Map map,
                                         java.lang.Object key)

Gets a Double from a Map in a null-safe manner.

The Double is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Double, null if null map input

getMap

public static java.util.Map getMap(java.util.Map map,
                                   java.lang.Object key)

Gets a Map from a Map in a null-safe manner.

If the value returned from the specified map is not a Map then null is returned.

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Map, null if null map input

getObject

public static java.lang.Object getObject(java.util.Map map,
                                         java.lang.Object key,
                                         java.lang.Object defaultValue)

Looks up the given key in the given map, converting null into the given default value.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null

Returns:

the value in the map, or defaultValue if the original value is null or the map is null

getString

public static java.lang.String getString(java.util.Map map,
                                         java.lang.Object key,
                                         java.lang.String defaultValue)

Looks up the given key in the given map, converting the result into a string, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a string, or defaultValue if the original value is null, the map is null or the string conversion fails

getBoolean

public static java.lang.Boolean getBoolean(java.util.Map map,
                                           java.lang.Object key,
                                           java.lang.Boolean defaultValue)

Looks up the given key in the given map, converting the result into a boolean, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a boolean, or defaultValue if the original value is null, the map is null or the boolean conversion fails

getNumber

public static java.lang.Number getNumber(java.util.Map map,
                                         java.lang.Object key,
                                         java.lang.Number defaultValue)

Looks up the given key in the given map, converting the result into a number, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getByte

public static java.lang.Byte getByte(java.util.Map map,
                                     java.lang.Object key,
                                     java.lang.Byte defaultValue)

Looks up the given key in the given map, converting the result into a byte, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getShort

public static java.lang.Short getShort(java.util.Map map,
                                       java.lang.Object key,
                                       java.lang.Short defaultValue)

Looks up the given key in the given map, converting the result into a short, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getInteger

public static java.lang.Integer getInteger(java.util.Map map,
                                           java.lang.Object key,
                                           java.lang.Integer defaultValue)

Looks up the given key in the given map, converting the result into an integer, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getLong

public static java.lang.Long getLong(java.util.Map map,
                                     java.lang.Object key,
                                     java.lang.Long defaultValue)

Looks up the given key in the given map, converting the result into a long, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getFloat

public static java.lang.Float getFloat(java.util.Map map,
                                       java.lang.Object key,
                                       java.lang.Float defaultValue)

Looks up the given key in the given map, converting the result into a float, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getDouble

public static java.lang.Double getDouble(java.util.Map map,
                                         java.lang.Object key,
                                         java.lang.Double defaultValue)

Looks up the given key in the given map, converting the result into a double, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getMap

public static java.util.Map getMap(java.util.Map map,
                                   java.lang.Object key,
                                   java.util.Map defaultValue)

Looks up the given key in the given map, converting the result into a map, using the default value if the the conversion fails.

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the map conversion fails

getBooleanValue

public static boolean getBooleanValue(java.util.Map map,
                                      java.lang.Object key)

Gets a boolean from a Map in a null-safe manner.

If the value is a Boolean its value is returned. If the value is a String and it equals 'true' ignoring case then true is returned, otherwise false. If the value is a Number an integer zero value returns false and non-zero returns true. Otherwise, false is returned.

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Boolean, false if null map input

getByteValue

public static byte getByteValue(java.util.Map map,
                                java.lang.Object key)

Gets a byte from a Map in a null-safe manner.

The byte is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a byte, 0 if null map input

getShortValue

public static short getShortValue(java.util.Map map,
                                  java.lang.Object key)

Gets a short from a Map in a null-safe manner.

The short is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a short, 0 if null map input

getIntValue

public static int getIntValue(java.util.Map map,
                              java.lang.Object key)

Gets an int from a Map in a null-safe manner.

The int is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as an int, 0 if null map input

getLongValue

public static long getLongValue(java.util.Map map,
                                java.lang.Object key)

Gets a long from a Map in a null-safe manner.

The long is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a long, 0L if null map input

getFloatValue

public static float getFloatValue(java.util.Map map,
                                  java.lang.Object key)

Gets a float from a Map in a null-safe manner.

The float is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a float, 0.0F if null map input

getDoubleValue

public static double getDoubleValue(java.util.Map map,
                                    java.lang.Object key)

Gets a double from a Map in a null-safe manner.

The double is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a double, 0.0 if null map input

getBooleanValue

public static boolean getBooleanValue(java.util.Map map,
                                      java.lang.Object key,
                                      boolean defaultValue)

Gets a boolean from a Map in a null-safe manner, using the default value if the the conversion fails.

If the value is a Boolean its value is returned. If the value is a String and it equals 'true' ignoring case then true is returned, otherwise false. If the value is a Number an integer zero value returns false and non-zero returns true. Otherwise, defaultValue is returned.

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a Boolean, defaultValue if null map input

getByteValue

public static byte getByteValue(java.util.Map map,
                                java.lang.Object key,
                                byte defaultValue)

Gets a byte from a Map in a null-safe manner, using the default value if the the conversion fails.

The byte is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a byte, defaultValue if null map input

getShortValue

public static short getShortValue(java.util.Map map,
                                  java.lang.Object key,
                                  short defaultValue)

Gets a short from a Map in a null-safe manner, using the default value if the the conversion fails.

The short is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a short, defaultValue if null map input

getIntValue

public static int getIntValue(java.util.Map map,
                              java.lang.Object key,
                              int defaultValue)

Gets an int from a Map in a null-safe manner, using the default value if the the conversion fails.

The int is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as an int, defaultValue if null map input

getLongValue

public static long getLongValue(java.util.Map map,
                                java.lang.Object key,
                                long defaultValue)

Gets a long from a Map in a null-safe manner, using the default value if the the conversion fails.

The long is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a long, defaultValue if null map input

getFloatValue

public static float getFloatValue(java.util.Map map,
                                  java.lang.Object key,
                                  float defaultValue)

Gets a float from a Map in a null-safe manner, using the default value if the the conversion fails.

The float is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a float, defaultValue if null map input

getDoubleValue

public static double getDoubleValue(java.util.Map map,
                                    java.lang.Object key,
                                    double defaultValue)

Gets a double from a Map in a null-safe manner, using the default value if the the conversion fails.

The double is obtained from the results of getNumber(Map,Object).

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a double, defaultValue if null map input

toProperties

public static java.util.Properties toProperties(java.util.Map map)

Gets a new Properties object initialised with the values from a Map. A null input will return an empty properties object.

Parameters:

map - the map to convert to a Properties object, may not be null

Returns:

the properties object

toMap

public static java.util.Map toMap(java.util.ResourceBundle resourceBundle)

Creates a new HashMap using data copied from a ResourceBundle.

Parameters:

resourceBundle - the resource bundle to convert, may not be null

Returns:

the hashmap containing the data

Throws:

java.lang.NullPointerException - if the bundle is null

verbosePrint

public static void verbosePrint(java.io.PrintStream out,
                                java.lang.Object label,
                                java.util.Map map)

Prints the given map with nice line breaks.

This method prints a nicely formatted String describing the Map. Each map entry will be printed with key and value. When the value is a Map, recursive behaviour occurs.

This method is NOT thread-safe in any special way. You must manually synchronize on either this class or the stream as required.

Parameters:

out - the stream to print to, must not be null

label - The label to be used, may be null. If null, the label is not output. It typically represents the name of the property in a bean or similar.

map - The map to print, may be null. If null, the text 'null' is output.

Throws:

java.lang.NullPointerException - if the stream is null

debugPrint

public static void debugPrint(java.io.PrintStream out,
                              java.lang.Object label,
                              java.util.Map map)

Prints the given map with nice line breaks.

This method prints a nicely formatted String describing the Map. Each map entry will be printed with key, value and value classname. When the value is a Map, recursive behaviour occurs.

This method is NOT thread-safe in any special way. You must manually synchronize on either this class or the stream as required.

Parameters:

out - the stream to print to, must not be null

label - The label to be used, may be null. If null, the label is not output. It typically represents the name of the property in a bean or similar.

map - The map to print, may be null. If null, the text 'null' is output.

Throws:

java.lang.NullPointerException - if the stream is null

invertMap

public static java.util.Map invertMap(java.util.Map map)

Inverts the supplied map returning a new HashMap such that the keys of the input are swapped with the values.

This operation assumes that the inverse mapping is well defined. If the input map had multiple entries with the same value mapped to different keys, the returned map will map one of those keys to the value, but the exact key which will be mapped is undefined.

Parameters:

map - the map to invert, may not be null

Returns:

a new HashMap containing the inverted data

Throws:

java.lang.NullPointerException - if the map is null

safeAddToMap

public static void safeAddToMap(java.util.Map map,
                                java.lang.Object key,
                                java.lang.Object value)
                         throws java.lang.NullPointerException

Protects against adding null values to a map.

This method checks the value being added to the map, and if it is null it is replaced by an empty string.

This could be useful if the map does not accept null values, or for receiving data from a source that may provide null or empty string which should be held in the same way in the map.

Keys are not validated.

Parameters:

map - the map to add to, may not be null

key - the key

value - the value, null converted to ""

Throws:

java.lang.NullPointerException - if the map is null

putAll

public static java.util.Map putAll(java.util.Map map,
                                   java.lang.Object[] array)

Puts all the keys and values from the specified array into the map.

This method is an alternative to the Map.putAll(java.util.Map) method and constructors. It allows you to build a map from an object array of various possible styles.

If the first entry in the object array implements Map.Entry or KeyValue then the key and value are added from that object. If the first entry in the object array is an object array itself, then it is assumed that index 0 in the sub-array is the key and index 1 is the value. Otherwise, the array is treated as keys and values in alternate indices.

For example, to create a color map:

 Map colorMap = MapUtils.putAll(new HashMap(), new String[][] {
     {"RED", "#FF0000"},
     {"GREEN", "#00FF00"},
     {"BLUE", "#0000FF"}
 });
 

or:

 Map colorMap = MapUtils.putAll(new HashMap(), new String[] {
     "RED", "#FF0000",
     "GREEN", "#00FF00",
     "BLUE", "#0000FF"
 });
 

or:

 Map colorMap = MapUtils.putAll(new HashMap(), new Map.Entry[] {
     new DefaultMapEntry("RED", "#FF0000"),
     new DefaultMapEntry("GREEN", "#00FF00"),
     new DefaultMapEntry("BLUE", "#0000FF")
 });
 

Parameters:

map - the map to populate, must not be null

array - an array to populate from, null ignored

Returns:

the input map

Throws:

java.lang.NullPointerException - if map is null

java.lang.IllegalArgumentException - if sub-array or entry matching used and an entry is invalid

java.lang.ClassCastException - if the array contents is mixed

Since:

Commons Collections 3.2

isEmpty

public static boolean isEmpty(java.util.Map map)

Null-safe check if the specified map is empty.

Null returns true.

Parameters:

map - the map to check, may be null

Returns:

true if empty or null

Since:

Commons Collections 3.2

isNotEmpty

public static boolean isNotEmpty(java.util.Map map)

Null-safe check if the specified map is not empty.

Null returns false.

Parameters:

map - the map to check, may be null

Returns:

true if non-null and non-empty

Since:

Commons Collections 3.2

synchronizedMap

public static java.util.Map synchronizedMap(java.util.Map map)

Returns a synchronized map backed by the given map.

You must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:

 Map m = MapUtils.synchronizedMap(myMap);
 Set s = m.keySet();  // outside synchronized block
 synchronized (m) {  // synchronized on MAP!
     Iterator i = s.iterator();
     while (i.hasNext()) {
         process (i.next());
     }
 }
 

This method uses the implementation in Collections.

Parameters:

map - the map to synchronize, must not be null

Returns:

a synchronized map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the map is null

unmodifiableMap

public static java.util.Map unmodifiableMap(java.util.Map map)

Returns an unmodifiable map backed by the given map.

This method uses the implementation in the decorators subpackage.

Parameters:

map - the map to make unmodifiable, must not be null

Returns:

an unmodifiable map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the map is null

predicatedMap

public static java.util.Map predicatedMap(java.util.Map map,
                                          Predicate keyPred,
                                          Predicate valuePred)

Returns a predicated (validating) map backed by the given map.

Only objects that pass the tests in the given predicates can be added to the map. Trying to add an invalid object results in an IllegalArgumentException. Keys must pass the key predicate, values must pass the value predicate. It is important not to use the original map after invoking this method, as it is a backdoor for adding invalid objects.

Parameters:

map - the map to predicate, must not be null

keyPred - the predicate for keys, null means no check

valuePred - the predicate for values, null means no check

Returns:

a predicated map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the Map is null

typedMap

public static java.util.Map typedMap(java.util.Map map,
                                     java.lang.Class keyType,
                                     java.lang.Class valueType)

Returns a typed map backed by the given map.

Only keys and values of the specified types can be added to the map.

Parameters:

map - the map to limit to a specific type, must not be null

keyType - the type of keys which may be added to the map, must not be null

valueType - the type of values which may be added to the map, must not be null

Returns:

a typed map backed by the specified map

Throws:

java.lang.IllegalArgumentException - if the Map or Class is null

transformedMap

public static java.util.Map transformedMap(java.util.Map map,
                                           Transformer keyTransformer,
                                           Transformer valueTransformer)

Returns a transformed map backed by the given map.

This method returns a new map (decorating the specified map) that will transform any new entries added to it. Existing entries in the specified map will not be transformed. If you want that behaviour, see TransformedMap.decorateTransform(java.util.Map, org.apache.commons.collections.Transformer, org.apache.commons.collections.Transformer).

Each object is passed through the transformers as it is added to the Map. It is important not to use the original map after invoking this method, as it is a backdoor for adding untransformed objects.

If there are any elements already in the map being decorated, they are NOT transformed.

Parameters:

map - the map to transform, must not be null, typically empty

keyTransformer - the transformer for the map keys, null means no transformation

valueTransformer - the transformer for the map values, null means no transformation

Returns:

a transformed map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the Map is null

fixedSizeMap

public static java.util.Map fixedSizeMap(java.util.Map map)

Returns a fixed-sized map backed by the given map. Elements may not be added or removed from the returned map, but existing elements can be changed (for instance, via the Map.put(Object,Object) method).

Parameters:

map - the map whose size to fix, must not be null

Returns:

a fixed-size map backed by that map

Throws:

java.lang.IllegalArgumentException - if the Map is null

lazyMap

public static java.util.Map lazyMap(java.util.Map map,
                                    Factory factory)

Returns a "lazy" map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key.

For instance:

 Factory factory = new Factory() {
     public Object create() {
         return new Date();
     }
 }
 Map lazyMap = MapUtils.lazyMap(new HashMap(), factory);
 Object obj = lazyMap.get("test");
 

After the above code is executed, obj will contain a new Date instance. Furthermore, that Date instance is the value for the "test" key in the map.

Parameters:

map - the map to make lazy, must not be null

factory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the Map or Factory is null

lazyMap

public static java.util.Map lazyMap(java.util.Map map,
                                    Transformer transformerFactory)

Returns a "lazy" map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key. The factory is a Transformer that will be passed the key which it must transform into the value.

For instance:

 Transformer factory = new Transformer() {
     public Object transform(Object mapKey) {
         return new File(mapKey);
     }
 }
 Map lazyMap = MapUtils.lazyMap(new HashMap(), factory);
 Object obj = lazyMap.get("C:/dev");
 

After the above code is executed, obj will contain a new File instance for the C drive dev directory. Furthermore, that File instance is the value for the "C:/dev" key in the map.

If a lazy map is wrapped by a synchronized map, the result is a simple synchronized cache. When an object is not is the cache, the cache itself calls back to the factory Transformer to populate itself, all within the same synchronized block.

Parameters:

map - the map to make lazy, must not be null

transformerFactory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the Map or Transformer is null

orderedMap

public static java.util.Map orderedMap(java.util.Map map)

Returns a map that maintains the order of keys that are added backed by the given map.

If a key is added twice, the order is determined by the first add. The order is observed through the keySet, values and entrySet.

Parameters:

map - the map to order, must not be null

Returns:

an ordered map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the Map is null

multiValueMap

public static java.util.Map multiValueMap(java.util.Map map)

Creates a mult-value map backed by the given map which returns collections of type ArrayList.

Parameters:

map - the map to decorate

Returns:

a multi-value map backed by the given map which returns ArrayLists of values.

Since:

Commons Collections 3.2

See Also:

MultiValueMap

multiValueMap

public static java.util.Map multiValueMap(java.util.Map map,
                                          java.lang.Class collectionClass)

Creates a multi-value map backed by the given map which returns collections of the specified type.

Parameters:

map - the map to decorate

collectionClass - the type of collections to return from the map (must contain public no-arg constructor and extend Collection).

Returns:

a multi-value map backed by the given map which returns collections of the specified type

Since:

Commons Collections 3.2

See Also:

MultiValueMap

multiValueMap

public static java.util.Map multiValueMap(java.util.Map map,
                                          Factory collectionFactory)

Creates a multi-value map backed by the given map which returns collections created by the specified collection factory.

Parameters:

map - the map to decorate

collectionFactory - a factor which creates collection objects

Returns:

a multi-value map backed by the given map which returns collections created by the specified collection factory

Since:

Commons Collections 3.2

See Also:

MultiValueMap

synchronizedSortedMap

public static java.util.Map synchronizedSortedMap(java.util.SortedMap map)

Returns a synchronized sorted map backed by the given sorted map.

You must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:

 Map m = MapUtils.synchronizedSortedMap(myMap);
 Set s = m.keySet();  // outside synchronized block
 synchronized (m) {  // synchronized on MAP!
     Iterator i = s.iterator();
     while (i.hasNext()) {
         process (i.next());
     }
 }
 

This method uses the implementation in Collections.

Parameters:

map - the map to synchronize, must not be null

Returns:

a synchronized map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the map is null

unmodifiableSortedMap

public static java.util.Map unmodifiableSortedMap(java.util.SortedMap map)

Returns an unmodifiable sorted map backed by the given sorted map.

This method uses the implementation in the decorators subpackage.

Parameters:

map - the sorted map to make unmodifiable, must not be null

Returns:

an unmodifiable map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the map is null

predicatedSortedMap

public static java.util.SortedMap predicatedSortedMap(java.util.SortedMap map,
                                                      Predicate keyPred,
                                                      Predicate valuePred)

Returns a predicated (validating) sorted map backed by the given map.

Only objects that pass the tests in the given predicates can be added to the map. Trying to add an invalid object results in an IllegalArgumentException. Keys must pass the key predicate, values must pass the value predicate. It is important not to use the original map after invoking this method, as it is a backdoor for adding invalid objects.

Parameters:

map - the map to predicate, must not be null

keyPred - the predicate for keys, null means no check

valuePred - the predicate for values, null means no check

Returns:

a predicated map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the SortedMap is null

typedSortedMap

public static java.util.SortedMap typedSortedMap(java.util.SortedMap map,
                                                 java.lang.Class keyType,
                                                 java.lang.Class valueType)

Returns a typed sorted map backed by the given map.

Only keys and values of the specified types can be added to the map.

Parameters:

map - the map to limit to a specific type, must not be null

keyType - the type of keys which may be added to the map, must not be null

valueType - the type of values which may be added to the map, must not be null

Returns:

a typed map backed by the specified map

transformedSortedMap

public static java.util.SortedMap transformedSortedMap(java.util.SortedMap map,
                                                       Transformer keyTransformer,
                                                       Transformer valueTransformer)

Returns a transformed sorted map backed by the given map.

This method returns a new sorted map (decorating the specified map) that will transform any new entries added to it. Existing entries in the specified map will not be transformed. If you want that behaviour, see TransformedSortedMap.decorateTransform(java.util.SortedMap, org.apache.commons.collections.Transformer, org.apache.commons.collections.Transformer).

Each object is passed through the transformers as it is added to the Map. It is important not to use the original map after invoking this method, as it is a backdoor for adding untransformed objects.

If there are any elements already in the map being decorated, they are NOT transformed.

Parameters:

map - the map to transform, must not be null, typically empty

keyTransformer - the transformer for the map keys, null means no transformation

valueTransformer - the transformer for the map values, null means no transformation

Returns:

a transformed map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the SortedMap is null

fixedSizeSortedMap

public static java.util.SortedMap fixedSizeSortedMap(java.util.SortedMap map)

Returns a fixed-sized sorted map backed by the given sorted map. Elements may not be added or removed from the returned map, but existing elements can be changed (for instance, via the Map.put(Object,Object) method).

Parameters:

map - the map whose size to fix, must not be null

Returns:

a fixed-size map backed by that map

Throws:

java.lang.IllegalArgumentException - if the SortedMap is null

lazySortedMap

public static java.util.SortedMap lazySortedMap(java.util.SortedMap map,
                                                Factory factory)

Returns a "lazy" sorted map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key.

For instance:

 Factory factory = new Factory() {
     public Object create() {
         return new Date();
     }
 }
 SortedMap lazy = MapUtils.lazySortedMap(new TreeMap(), factory);
 Object obj = lazy.get("test");
 

After the above code is executed, obj will contain a new Date instance. Furthermore, that Date instance is the value for the "test" key.

Parameters:

map - the map to make lazy, must not be null

factory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the SortedMap or Factory is null

lazySortedMap

public static java.util.SortedMap lazySortedMap(java.util.SortedMap map,
                                                Transformer transformerFactory)

Returns a "lazy" sorted map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key. The factory is a Transformer that will be passed the key which it must transform into the value.

For instance:

 Transformer factory = new Transformer() {
     public Object transform(Object mapKey) {
         return new File(mapKey);
     }
 }
 SortedMap lazy = MapUtils.lazySortedMap(new TreeMap(), factory);
 Object obj = lazy.get("C:/dev");
 

After the above code is executed, obj will contain a new File instance for the C drive dev directory. Furthermore, that File instance is the value for the "C:/dev" key in the map.

If a lazy map is wrapped by a synchronized map, the result is a simple synchronized cache. When an object is not is the cache, the cache itself calls back to the factory Transformer to populate itself, all within the same synchronized block.

Parameters:

map - the map to make lazy, must not be null

transformerFactory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.IllegalArgumentException - if the Map or Transformer is null