Package com.ibm.icu.dev.util

Class CollectionUtilities

java.lang.Object

com.ibm.icu.dev.util.CollectionUtilities

public final class CollectionUtilities
extends Object

Utilities that ought to be on collections, but aren't

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CollectionUtilities.CollectionComparator<T extends Comparable>
static class	CollectionUtilities.ComparableComparator<T extends Comparable>
static class	CollectionUtilities.FilteredIterator	For producing filtered iterators
static class	CollectionUtilities.InverseMatcher<T>	Reverse a match
static class	CollectionUtilities.MapComparator<K extends Comparable,V extends Comparable>
static interface	CollectionUtilities.ObjectMatcher<T>	Matches item.
static class	CollectionUtilities.PrefixIterator
static class	CollectionUtilities.RegexIterator
static class	CollectionUtilities.SetComparator<T extends Comparable>

Field Summary

Fields

Modifier and Type	Field	Description
static final int	A_PROPER_OVERLAPS_B	Used for results of getContainmentRelation
static final int	A_PROPER_SUBSET_OF_B	Used for results of getContainmentRelation
static final int	A_PROPER_SUPERSET_B	Used for results of getContainmentRelation
static final int	ALL_EMPTY	Used for results of getContainmentRelation
static final int	NOT_A_DISJOINT_B	Used for results of getContainmentRelation
static final int	NOT_A_EQUALS_B	Used for results of getContainmentRelation
static final int	NOT_A_SUBSET_B	Used for results of getContainmentRelation
static final int	NOT_A_SUPERSET_B	Used for results of getContainmentRelation

Constructor Summary

Constructors

Constructor	Description
CollectionUtilities()

Method Summary

Modifier and Type	Method	Description
static <T, U extends Collection<T>> U	addAll(Iterator<T> source, U target)	Add all items in iterator to target collection
static <T> Map<T,T>	asMap(T[][] source)
static <T> Map<T,T>	asMap(T[][] source, Map<T,T> target, boolean reverse)	Utility like Arrays.asList()
static <T extends Comparable> int	compare(Iterator<T> iterator1, Iterator<T> iterator2)	Compare iterators
static <T extends Comparable> int	compare(T a, T b)	Compare, allowing nulls and putting them first
static <T extends Comparable, U extends Collection<T>> int	compare(U o1, U o2)	Compare, with shortest first, and otherwise lexicographically
static <K extends Comparable, V extends Comparable, T extends Map.Entry<K, V>> int	compareEntrySets(Collection<T> o1, Collection<T> o2)
static boolean	containsAll(Collection a, Collection b)
static boolean	containsNone(Collection a, Collection b)
static boolean	containsSome(Collection a, Collection b)
static <T> boolean	equals(T a, T b)	Compare, allowing nulls
static <T, U extends Collection<T>> T	getBest(U c, Comparator<T> comp, int direction)	Get the "best" in collection.
static int	getContainmentRelation(Collection a, Collection b)	Assesses all the possible containment relations between collections A and B with one call. Returns an int with bits set, according to a "Venn Diagram" view of A vs B. NOT_A_SUPERSET_B: a - b != {} NOT_A_DISJOINT_B: a * b != {} // * is intersects NOT_A_SUBSET_B: b - a != {} Thus the bits can be used to get the following relations: for A_SUPERSET_B, use (x invalid input: '&' CollectionUtilities.NOT_A_SUPERSET_B) == 0 for A_SUBSET_B, use (x invalid input: '&' CollectionUtilities.NOT_A_SUBSET_B) == 0 for A_EQUALS_B, use (x invalid input: '&' CollectionUtilities.NOT_A_EQUALS_B) == 0 for A_DISJOINT_B, use (x invalid input: '&' CollectionUtilities.NOT_A_DISJOINT_B) == 0 for A_OVERLAPS_B, use (x invalid input: '&' CollectionUtilities.NOT_A_DISJOINT_B) != 0
<T, U extends Collection<T>> T	getFirst(U c)	Get first item in collection, or null if there is none.
static <T> String	join(T[] array, String separator)	Join an array of items.
static <T, U extends Iterable<T>> String	join(U collection, String separator)	Join a collection of items.
static int	matchesAt(CharSequence text, int offset, CharSequence other)	Does one string contain another, starting at a specific offset?
static <K, V> Map<K,V>	removeAll(Map<K,V> m, Collection<K> itemsToRemove)	Utility that ought to be on Map
static <T, U extends Collection<T>> U	removeAll(U c, CollectionUtilities.ObjectMatcher<T> f)	Remove matching items
static <T, U extends Collection<T>> U	retainAll(U c, CollectionUtilities.ObjectMatcher<T> f)	Retain matching items
static int	size(Iterator source)	Get the size of an iterator (number of items in it).

Methods inherited from class java.lang.Object

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

Field Details

ALL_EMPTY

public static final int ALL_EMPTY

Used for results of getContainmentRelation

See Also:

• Constant Field Values

NOT_A_SUPERSET_B

public static final int NOT_A_SUPERSET_B

Used for results of getContainmentRelation

See Also:

• Constant Field Values

NOT_A_DISJOINT_B

public static final int NOT_A_DISJOINT_B

Used for results of getContainmentRelation

See Also:

• Constant Field Values

NOT_A_SUBSET_B

public static final int NOT_A_SUBSET_B

Used for results of getContainmentRelation

See Also:

• Constant Field Values

NOT_A_EQUALS_B

public static final int NOT_A_EQUALS_B

Used for results of getContainmentRelation

See Also:

• Constant Field Values

A_PROPER_SUBSET_OF_B

public static final int A_PROPER_SUBSET_OF_B

Used for results of getContainmentRelation

See Also:

• Constant Field Values

A_PROPER_SUPERSET_B

public static final int A_PROPER_SUPERSET_B

Used for results of getContainmentRelation

See Also:

• Constant Field Values

A_PROPER_OVERLAPS_B

public static final int A_PROPER_OVERLAPS_B

Used for results of getContainmentRelation

See Also:

• Constant Field Values

Constructor Details

CollectionUtilities

public CollectionUtilities()

Method Details

join

public static <T> String join(T[] array,
 String separator)

Join an array of items.

Type Parameters:

T -

Parameters:

array -

separator -

Returns:

string

join

public static <T,
U extends Iterable<T>> String join(U collection,
 String separator)

Join a collection of items.

Type Parameters:

T -

U -

Parameters:

collection -

separator -

array -

Returns:

string

asMap

public static <T> Map<T,T> asMap(T[][] source,
 Map<T,T> target,
 boolean reverse)

Utility like Arrays.asList()

Type Parameters:

T -

Parameters:

source -

target -

reverse -

Returns:

addAll

public static <T,
U extends Collection<T>> U addAll(Iterator<T> source,
 U target)

Add all items in iterator to target collection

Type Parameters:

T -

U -

Parameters:

source -

target -

Returns:

size

public static int size(Iterator source)

Get the size of an iterator (number of items in it).

Parameters:

source -

Returns:

asMap

public static <T> Map<T,T> asMap(T[][] source)

Type Parameters:

T -

Parameters:

source -

Returns:

removeAll

public static <K,
V> Map<K,V> removeAll(Map<K,V> m,
 Collection<K> itemsToRemove)

Utility that ought to be on Map

Type Parameters:

K -

V -

Parameters:

m -

itemsToRemove -

Returns:

map passed in

getFirst

public <T,
U extends Collection<T>> T getFirst(U c)

Get first item in collection, or null if there is none.

Type Parameters:

T -

U -

Parameters:

c -

Returns:

first item

getBest

public static <T,
U extends Collection<T>> T getBest(U c,
 Comparator<T> comp,
 int direction)

Get the "best" in collection. That is the least if direction is invalid input: '<' 0, otherwise the greatest. The first is chosen if there are multiples.

Type Parameters:

T -

U -

Parameters:

c -

comp -

direction -

Returns:

removeAll

public static <T,
U extends Collection<T>> U removeAll(U c,
 CollectionUtilities.ObjectMatcher<T> f)

Remove matching items

Type Parameters:

T -

U -

Parameters:

c -

f -

Returns:

retainAll

public static <T,
U extends Collection<T>> U retainAll(U c,
 CollectionUtilities.ObjectMatcher<T> f)

Retain matching items

Type Parameters:

T -

U -

Parameters:

c -

f -

Returns:

containsSome

public static boolean containsSome(Collection a,
 Collection b)

Parameters:

a -

b -

Returns:

containsAll

public static boolean containsAll(Collection a,
 Collection b)

containsNone

public static boolean containsNone(Collection a,
 Collection b)

getContainmentRelation

public static int getContainmentRelation(Collection a,
 Collection b)

Assesses all the possible containment relations between collections A and B with one call.
Returns an int with bits set, according to a "Venn Diagram" view of A vs B.
NOT_A_SUPERSET_B: a - b != {}
NOT_A_DISJOINT_B: a * b != {} // * is intersects
NOT_A_SUBSET_B: b - a != {}
Thus the bits can be used to get the following relations:
for A_SUPERSET_B, use (x invalid input: '&' CollectionUtilities.NOT_A_SUPERSET_B) == 0
for A_SUBSET_B, use (x invalid input: '&' CollectionUtilities.NOT_A_SUBSET_B) == 0
for A_EQUALS_B, use (x invalid input: '&' CollectionUtilities.NOT_A_EQUALS_B) == 0
for A_DISJOINT_B, use (x invalid input: '&' CollectionUtilities.NOT_A_DISJOINT_B) == 0
for A_OVERLAPS_B, use (x invalid input: '&' CollectionUtilities.NOT_A_DISJOINT_B) != 0

matchesAt

public static int matchesAt(CharSequence text,
 int offset,
 CharSequence other)

Does one string contain another, starting at a specific offset?

Parameters:

text -

offset -

other -

Returns:

equals

public static <T> boolean equals(T a,
 T b)

Compare, allowing nulls

Parameters:

a -

b -

Returns:

compare

public static <T extends Comparable> int compare(T a,
 T b)

Compare, allowing nulls and putting them first

Parameters:

a -

b -

Returns:

compare

public static <T extends Comparable> int compare(Iterator<T> iterator1,
 Iterator<T> iterator2)

Compare iterators

Parameters:

iterator1 -

iterator2 -

Returns:

compare

public static <T extends Comparable,
U extends Collection<T>>
int compare(U o1,
 U o2)

Compare, with shortest first, and otherwise lexicographically

Parameters:

a -

b -

Returns:

compare

public static <T extends Comparable,
U extends Set<T>>
int compare(U o1,
 U o2)

Compare, with shortest first, and otherwise lexicographically

Parameters:

a -

b -

Returns:

compare

public static <K extends Comparable,
V extends Comparable,
T extends Map.Entry<K,
V>>
int compare(T a,
 T b)

Compare, allowing nulls and putting them first

Parameters:

a -

b -

Returns:

compareEntrySets

public static <K extends Comparable,
V extends Comparable,
T extends Map.Entry<K,
V>>
int compareEntrySets(Collection<T> o1,
 Collection<T> o2)