net.sourceforge.pmd.util

Class CollectionUtil

java.lang.Object

net.sourceforge.pmd.util.CollectionUtil

public final class CollectionUtil
extends Object

Generic collection and array-related utility functions for java.util types. See ClassUtil for comparable facilities for short name lookup.

Version:

$Revision$

Author:

Brian Remedios

Field Summary

Fields

Modifier and Type	Field and Description
static TypeMap	COLLECTION_CLASSES_BY_NAMES
static TypeMap	COLLECTION_INTERFACES_BY_NAMES

Method Summary

Methods

Modifier and Type	Method and Description
static int	addWithoutDuplicates(Collection<String> source, Collection<String> target) Add elements from the source to the target as long as they don't already exist there.
static <T> T[]	addWithoutDuplicates(T[] values, T newValue) If the newValue is already held within the values array then the values array is returned, otherwise a new array is created appending the newValue to the end.
static <T> T[]	addWithoutDuplicates(T[] values, T[] newValues) Returns an array of values as a union set of the two input arrays.
static boolean	areEqual(Object value, Object otherValue) A comprehensive isEqual method that handles nulls and arrays safely.
static <T> boolean	areSemanticEquals(T[] a, T[] b) Returns true if both arrays are if both are null or have zero-length, otherwise return the false if their respective elements are not equal by position.
static boolean	arraysAreEqual(Object value, Object otherValue) Returns true if the objects are array instances and each of their elements compares via equals as well.
static <T> Set<T>	asSet(T[] items) Returns the items as a populated set.
static Class<?>	getCollectionTypeFor(String shortName) Returns the collection type if we recognize it by its short name.
static <K,V> Map<V,K>	invertedMapFrom(Map<K,V> source) Returns a map based on the source but with the key & values swapped.
static boolean	isCollectionType(Class<?> clazzType, boolean includeInterfaces) Return whether we can identify the typeName as a java.util collection class or interface as specified.
static boolean	isCollectionType(String typeName, boolean includeInterfaces) Return whether we can identify the typeName as a java.util collection class or interface as specified.
static boolean	isEmpty(Object[] items) Returns whether the items array is null or has zero length.
static boolean	isNotEmpty(Object[] items) Returns whether the items array is non-null and has at least one entry.
static <K,V> Map<K,V>	mapFrom(K[] keys, V[] values) Creates and returns a map populated with the keyValuesSets where the value held by the tuples are they key and value in that order.
static boolean	valuesAreTransitivelyEqual(Object[] thisArray, Object[] thatArray) Returns whether the arrays are equal by examining each of their elements, even if they are arrays themselves.

Methods inherited from class java.lang.Object

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

Field Detail

COLLECTION_INTERFACES_BY_NAMES

public static final TypeMap COLLECTION_INTERFACES_BY_NAMES

COLLECTION_CLASSES_BY_NAMES

public static final TypeMap COLLECTION_CLASSES_BY_NAMES

Method Detail

addWithoutDuplicates

public static int addWithoutDuplicates(Collection<String> source,
                       Collection<String> target)

Add elements from the source to the target as long as they don't already exist there. Return the number of items actually added.

Parameters:

source -

target -

Returns:

int

getCollectionTypeFor

public static Class<?> getCollectionTypeFor(String shortName)

Returns the collection type if we recognize it by its short name.

Parameters:

shortName - String

Returns:

Class

isCollectionType

public static boolean isCollectionType(String typeName,
                       boolean includeInterfaces)

Return whether we can identify the typeName as a java.util collection class or interface as specified.

Parameters:

typeName - String

includeInterfaces - boolean

Returns:

boolean

isCollectionType

public static boolean isCollectionType(Class<?> clazzType,
                       boolean includeInterfaces)

Return whether we can identify the typeName as a java.util collection class or interface as specified.

Parameters:

clazzType - Class

includeInterfaces - boolean

Returns:

boolean

asSet

public static <T> Set<T> asSet(T[] items)

Returns the items as a populated set.

Parameters:

items - Object[]

Returns:

Set

mapFrom

public static <K,V> Map<K,V> mapFrom(K[] keys,
                     V[] values)

Creates and returns a map populated with the keyValuesSets where the value held by the tuples are they key and value in that order.

Parameters:

keys - K[]

values - V[]

Returns:

Map

invertedMapFrom

public static <K,V> Map<V,K> invertedMapFrom(Map<K,V> source)

Returns a map based on the source but with the key & values swapped.

Parameters:

source - Map

Returns:

Map

arraysAreEqual

public static boolean arraysAreEqual(Object value,
                     Object otherValue)

Returns true if the objects are array instances and each of their elements compares via equals as well.

Parameters:

value - Object

otherValue - Object

Returns:

boolean

valuesAreTransitivelyEqual

public static boolean valuesAreTransitivelyEqual(Object[] thisArray,
                                 Object[] thatArray)

Returns whether the arrays are equal by examining each of their elements, even if they are arrays themselves.

Parameters:

thisArray - Object[]

thatArray - Object[]

Returns:

boolean

areEqual

public static boolean areEqual(Object value,
               Object otherValue)

A comprehensive isEqual method that handles nulls and arrays safely.

Parameters:

value - Object

otherValue - Object

Returns:

boolean

isEmpty

public static boolean isEmpty(Object[] items)

Returns whether the items array is null or has zero length.

Parameters:

items -

Returns:

boolean

isNotEmpty

public static boolean isNotEmpty(Object[] items)

Returns whether the items array is non-null and has at least one entry.

Parameters:

items -

Returns:

boolean

areSemanticEquals

public static <T> boolean areSemanticEquals(T[] a,
                            T[] b)

Returns true if both arrays are if both are null or have zero-length, otherwise return the false if their respective elements are not equal by position.

Type Parameters:

T -

Parameters:

a -

b -

Returns:

boolean

addWithoutDuplicates

public static <T> T[] addWithoutDuplicates(T[] values,
                           T newValue)

If the newValue is already held within the values array then the values array is returned, otherwise a new array is created appending the newValue to the end.

Type Parameters:

T -

Parameters:

values -

newValue -

Returns:

an array containing the union of values and newValue

addWithoutDuplicates

public static <T> T[] addWithoutDuplicates(T[] values,
                           T[] newValues)

Returns an array of values as a union set of the two input arrays.

Type Parameters:

T -

Parameters:

values -

newValues -

Returns:

the union of the two arrays