| java.lang.Object
 java.util.Collections
| Collections | | public class Collections (Code) | | Collections contains static methods which operate on Collection classes.
since:
1.2 |
| Inner Class :static class SynchronizedRandomAccessList extends SynchronizedList implements RandomAccess | |
| Inner Class :static class SynchronizedList extends SynchronizedCollection implements List<E> | |
| Inner Class :static class SynchronizedMap implements Map<K, V>,Serializable | |
| Inner Class :static class SynchronizedSet extends SynchronizedCollection implements Set<E> | |
| Inner Class :static class SynchronizedSortedMap extends SynchronizedMap implements SortedMap<K, V> | |
| Inner Class :static class SynchronizedSortedSet extends SynchronizedSet implements SortedSet<E> | |
| Field Summary | |
| final public static List | EMPTY_LIST
An immutable, serializable, empty List. | | final public static Map | EMPTY_MAP
An immutable, serializable, empty Map. | | final public static Set | EMPTY_SET
An immutable, serializable, empty Set. |
| Method Summary | |
| public static boolean | addAll(Collection<? super T> c, T... a)
| | public static int | binarySearch(List<? extends Comparable<? super T>> list, T object)
Performs a binary search for the specified element in the specified
sorted List. | | public static int | binarySearch(List<? extends T> list, T object, Comparator<? super T> comparator)
Performs a binary search for the specified element in the specified
sorted List using the specified Comparator.
<
Parameters:
T - > The element type
Parameters:
list - the sorted List to search
Parameters:
object - the element to find
Parameters:
comparator - the Comparator. | | static E | checkType(E obj, Class<E> type)
Checks if specified object is instance of specified class. | | public static Collection<E> | checkedCollection(Collection<E> c, Class<E> type)
Returns a dynamically typesafe view of the specified collection. | | public static List<E> | checkedList(List<E> list, Class<E> type)
Returns a dynamically typesafe view of the specified list. | | public static Map<K, V> | checkedMap(Map<K, V> m, Class<K> keyType, Class<V> valueType)
Returns a dynamically typesafe view of the specified map. | | public static Set<E> | checkedSet(Set<E> s, Class<E> type)
Returns a dynamically typesafe view of the specified set. | | public static SortedMap<K, V> | checkedSortedMap(SortedMap<K, V> m, Class<K> keyType, Class<V> valueType)
Returns a dynamically typesafe view of the specified sorted map. | | public static SortedSet<E> | checkedSortedSet(SortedSet<E> s, Class<E> type)
Returns a dynamically typesafe view of the specified sorted set. | | public static void | copy(List<? super T> destination, List<? extends T> source)
Copies the elements from the source list to the destination list. | | public static boolean | disjoint(Collection c1, Collection c2)
| | final public static List<T> | emptyList()
Returns a type-safe empty, immutable
List . | | final public static Map<K, V> | emptyMap()
Returns a type-safe empty, immutable
Map . | | final public static Set<T> | emptySet()
Returns a type-safe empty, immutable
Set . | | public static Enumeration<T> | enumeration(Collection<T> collection)
Answers an Enumeration on the specified Collection. | | public static void | fill(List<? super T> list, T object)
Fills the specified List with the specified element. | | public static int | frequency(Collection c, Object o)
Returns the number of elements in the Collection that
match the Object passed. | | public static int | indexOfSubList(List list, List sublist)
Searches the list for sublist and answers
the beginning index of the first occurrence. | | public static int | lastIndexOfSubList(List list, List sublist)
Searches the list for sublist and answers
the beginning index of the last occurrence. | | public static ArrayList<T> | list(Enumeration<T> enumeration)
Answers an ArrayList with all the elements in the
enumeration. | | public static T | max(Collection<? extends T> collection)
Searches the specified Collection for the maximum element. | | public static T | max(Collection<? extends T> collection, Comparator<? super T> comparator)
Searches the specified Collection for the maximum element using the
specified Comparator. | | public static T | min(Collection<? extends T> collection)
Searches the specified Collection for the minimum element. | | public static T | min(Collection<? extends T> collection, Comparator<? super T> comparator)
Searches the specified Collection for the minimum element using the
specified Comparator. | | public static List<T> | nCopies(int length, T object)
Answers a List containing the specified number of the specified element. | | public static boolean | replaceAll(List<T> list, T obj, T obj2)
Replaces all occurrences of Object obj in
list with newObj. | | public static void | reverse(List list)
Returns the supplied List with the order of its contained
elements reversed. | | public static Comparator<T> | reverseOrder()
A Comparator which reverses the natural order of the elements. | | public static Comparator<T> | reverseOrder(Comparator<T> c)
Returns a
Comparator that reverses the order of the
Comparator passed. | | public static void | rotate(List lst, int dist)
Rotates the elements in List list by the distance
dist
e.g. | | public static void | shuffle(List list)
Moves every element of the List to a random new position in the list. | | public static void | shuffle(List list, Random random)
Moves every element of the List to a random new position in the list
using the specified random number generator. | | public static Set<E> | singleton(E object)
Answers a Set containing the specified element. | | public static List<E> | singletonList(E object)
Answers a List containing the specified element. | | public static Map<K, V> | singletonMap(K key, V value)
Answers a Map containing the specified key and value. | | public static void | sort(List<T> list)
Sorts the specified List in ascending order. | | public static void | sort(List<T> list, Comparator<? super T> comparator)
Sorts the specified List using the specified Comparator. | | public static void | swap(List list, int index1, int index2)
| | public static Collection<T> | synchronizedCollection(Collection<T> collection)
Answers a wrapper on the specified Collection which synchronizes all
access to the Collection. | | public static List<T> | synchronizedList(List<T> list)
Answers a wrapper on the specified List which synchronizes all access to
the List. | | public static Map<K, V> | synchronizedMap(Map<K, V> map)
Answers a wrapper on the specified Map which synchronizes all access to
the Map. | | public static Set<E> | synchronizedSet(Set<E> set)
Answers a wrapper on the specified Set which synchronizes all access to
the Set. | | public static SortedMap<K, V> | synchronizedSortedMap(SortedMap<K, V> map)
Answers a wrapper on the specified SortedMap which synchronizes all
access to the SortedMap. | | public static SortedSet<E> | synchronizedSortedSet(SortedSet<E> set)
Answers a wrapper on the specified SortedSet which synchronizes all
access to the SortedSet. | | public static Collection<E> | unmodifiableCollection(Collection<? extends E> collection)
Answers a wrapper on the specified Collection which throws an
UnsupportedOperationException whenever an attempt is made
to modify the Collection. | | public static List<E> | unmodifiableList(List<? extends E> list)
Answers a wrapper on the specified List which throws an
UnsupportedOperationException whenever an attempt is made
to modify the List. | | public static Map<K, V> | unmodifiableMap(Map<? extends K, ? extends V> map)
Answers a wrapper on the specified Map which throws an
UnsupportedOperationException whenever an attempt is made
to modify the Map. | | public static Set<E> | unmodifiableSet(Set<? extends E> set)
Answers a wrapper on the specified Set which throws an
UnsupportedOperationException whenever an attempt is made
to modify the Set. | | public static SortedMap<K, V> | unmodifiableSortedMap(SortedMap<K, ? extends V> map)
Answers a wrapper on the specified SortedMap which throws an
UnsupportedOperationException whenever an attempt is made
to modify the SortedMap. | | public static SortedSet<E> | unmodifiableSortedSet(SortedSet<E> set)
Answers a wrapper on the specified SortedSet which throws an
UnsupportedOperationException whenever an attempt is made
to modify the SortedSet. |
| addAll | | public static boolean addAll(Collection<? super T> c, T... a)(Code) | | Adds all the specified elements to the specified collection
Parameters:
c - the collection the elements are to be inserted into
Parameters:
a - the elements to insert true if the collection changed during insertion
throws:
UnsupportedOperationException - when the method is not supported
throws:
NullPointerException - when c or elements is null, or elements contains one or morenull elements and c doesn't support null elements |
| binarySearch | | public static int binarySearch(List<? extends Comparable<? super T>> list, T object)(Code) | | Performs a binary search for the specified element in the specified
sorted List.
Parameters:
list - the sorted List to search
Parameters:
object - the element to find the non-negative index of the element, or a negative index whichis the -index - 1 where the element would be inserted
throws:
ClassCastException - when an element in the List or the search element does notimplement Comparable, or cannot be compared to each other |
| binarySearch | | public static int binarySearch(List<? extends T> list, T object, Comparator<? super T> comparator)(Code) | | Performs a binary search for the specified element in the specified
sorted List using the specified Comparator.
<
Parameters:
T - > The element type
Parameters:
list - the sorted List to search
Parameters:
object - the element to find
Parameters:
comparator - the Comparator. If the comparator is null thenthe search uses the objects' natural ordering. the non-negative index of the element, or a negative index whichis the -index - 1 where the element would be inserted
throws:
ClassCastException - when an element in the list and the searched element cannotbe compared to each other using the Comparator |
| checkType | | static E checkType(E obj, Class<E> type)(Code) | | Checks if specified object is instance of specified class. Used for a
dynamically typesafe view of the collections.
Parameters:
obj - -object is to be checked
Parameters:
type - -class of object that should be specified object |
| checkedCollection | | public static Collection<E> checkedCollection(Collection<E> c, Class<E> type)(Code) | | Returns a dynamically typesafe view of the specified collection.
Parameters:
c - the collection
Parameters:
type - the type of the elements is permitted to insert a typesafe collection |
| checkedList | | public static List<E> checkedList(List<E> list, Class<E> type)(Code) | | Returns a dynamically typesafe view of the specified list.
Parameters:
list - the list
Parameters:
type - the type of the elements is permitted to insert a typesafe list |
| checkedMap | | public static Map<K, V> checkedMap(Map<K, V> m, Class<K> keyType, Class<V> valueType)(Code) | | Returns a dynamically typesafe view of the specified map.
Parameters:
m - the map
Parameters:
keyType - the type of keys permitted to be inserted
Parameters:
valueType - the type of values permitted to be inserted a typesafe map |
| checkedSet | | public static Set<E> checkedSet(Set<E> s, Class<E> type)(Code) | | Returns a dynamically typesafe view of the specified set.
Parameters:
s - the set
Parameters:
type - the type of the elements is permitted to insert a typesafe set |
| checkedSortedMap | | public static SortedMap<K, V> checkedSortedMap(SortedMap<K, V> m, Class<K> keyType, Class<V> valueType)(Code) | | Returns a dynamically typesafe view of the specified sorted map.
Parameters:
m - the sorted map
Parameters:
keyType - the type of keys permitted to be inserted
Parameters:
valueType - the type of values permitted to be inserted a typesafe sorted map |
| checkedSortedSet | | public static SortedSet<E> checkedSortedSet(SortedSet<E> s, Class<E> type)(Code) | | Returns a dynamically typesafe view of the specified sorted set.
Parameters:
s - the sorted set
Parameters:
type - the type of the elements is permitted to insert a typesafe sorted set |
| copy | | public static void copy(List<? super T> destination, List<? extends T> source)(Code) | | Copies the elements from the source list to the destination list.
Parameters:
destination -
Parameters:
source -
throws:
IndexOutOfBoundsException - when the destination List is smaller than the source List
throws:
UnsupportedOperationException - when replacing an element in the destination list is notsupported |
| disjoint | | public static boolean disjoint(Collection c1, Collection c2)(Code) | | Returns true if the collections have no elements in common
Parameters:
c1 - the first collection
Parameters:
c2 - the second collection true if the collections have no elements in common
throws:
NullPointerException - if one of the collections is null |
| enumeration | | public static Enumeration<T> enumeration(Collection<T> collection)(Code) | | Answers an Enumeration on the specified Collection.
Parameters:
collection - the Collection to enumerate an Enumeration |
| fill | | public static void fill(List<? super T> list, T object)(Code) | | Fills the specified List with the specified element.
Parameters:
list - the List to fill
Parameters:
object - the fill element
throws:
UnsupportedOperationException - when replacing an element in the List is not supported |
| frequency | | public static int frequency(Collection c, Object o)(Code) | |
Returns the number of elements in the Collection that
match the Object passed. If the Object is
null, then the number of null elements is
returned.
Parameters:
c - The Collection to search.
Parameters:
o - The Object to search for. The number of matching elements.
throws:
NullPointerException - if the Collection parameter isnull.
since:
1.5 |
| indexOfSubList | | public static int indexOfSubList(List list, List sublist)(Code) | | Searches the list for sublist and answers
the beginning index of the first occurrence.
-1 is returned if the sublist does not exist in
list
Parameters:
list - the List to search sublist in
Parameters:
sublist - the List to search in list the beginning index of the first occurrence ofsublist in list, or -1 |
| lastIndexOfSubList | | public static int lastIndexOfSubList(List list, List sublist)(Code) | | Searches the list for sublist and answers
the beginning index of the last occurrence.
-1 is returned if the sublist does not exist in
list
Parameters:
list - the List to search sublist in
Parameters:
sublist - the List to search in list the beginning index of the last occurrence ofsublist in list, or -1 |
| list | | public static ArrayList<T> list(Enumeration<T> enumeration)(Code) | | Answers an ArrayList with all the elements in the
enumeration. The elements in the returned ArrayList are
in the same order as in the enumeration.
Parameters:
enumeration - Enumeration and ArrayList |
| max | | public static T max(Collection<? extends T> collection)(Code) | | Searches the specified Collection for the maximum element.
Parameters:
collection - the Collection to search the maximum element in the Collection
throws:
ClassCastException - when an element in the Collection does not implementComparable or elements cannot be compared to each other |
| max | | public static T max(Collection<? extends T> collection, Comparator<? super T> comparator)(Code) | | Searches the specified Collection for the maximum element using the
specified Comparator.
Parameters:
collection - the Collection to search
Parameters:
comparator - the Comparator the maximum element in the Collection
throws:
ClassCastException - when elements in the Collection cannot be compared to eachother using the Comparator |
| min | | public static T min(Collection<? extends T> collection)(Code) | | Searches the specified Collection for the minimum element.
Parameters:
collection - the Collection to search the minimum element in the Collection
throws:
ClassCastException - when an element in the Collection does not implementComparable or elements cannot be compared to each other |
| min | | public static T min(Collection<? extends T> collection, Comparator<? super T> comparator)(Code) | | Searches the specified Collection for the minimum element using the
specified Comparator.
Parameters:
collection - the Collection to search
Parameters:
comparator - the Comparator the minimum element in the Collection
throws:
ClassCastException - when elements in the Collection cannot be compared to eachother using the Comparator |
| nCopies | | public static List<T> nCopies(int length, T object)(Code) | | Answers a List containing the specified number of the specified element.
The list cannot be modified.
Parameters:
length - the size of the returned List
Parameters:
object - the element a List containing length copies of the element
throws:
IllegalArgumentException - when length < 0 |
| replaceAll | | public static boolean replaceAll(List<T> list, T obj, T obj2)(Code) | | Replaces all occurrences of Object obj in
list with newObj. If the obj
is null, then all occurrences of null is
replaced with newObj.
Parameters:
list - the List to modify
Parameters:
obj - the Object to find and replace occurrences of.
Parameters:
obj2 - the Object to replace all occurrences of obj inlist true, if at least one occurrence of obj has beenfound in list
throws:
UnsupportedOperationException - if the list does not support setting elements |
| reverse | | public static void reverse(List list)(Code) | | Returns the supplied List with the order of its contained
elements reversed.
Parameters:
list - the List to reverse
throws:
UnsupportedOperationException - when replacing an element in the List is not supported |
| reverseOrder | | public static Comparator<T> reverseOrder(Comparator<T> c)(Code) | |
Returns a
Comparator that reverses the order of the
Comparator passed. If the Comparator passed
is null, then this method is equivalent to
Collections.reverseOrder() .
The Comparator that's returned is
Serializable if
the Comparator passed is serializable or null.
Parameters:
c - The Comparator to reverse or null. A Comparator instance.
See Also: Comparator
since:
1.5 |
| rotate | | public static void rotate(List lst, int dist)(Code) | | Rotates the elements in List list by the distance
dist
e.g. for a given list with elements [1, 2, 3, 4, 5, 6, 7, 8, 9, 0],
calling rotate(list, 3) or rotate(list, -7) would modify the list to look
like this: [8, 9, 0, 1, 2, 3, 4, 5, 6, 7]
Parameters:
lst -
Parameters:
dist - It can be any integer: 0, positive, negative, larger than thelist size |
| shuffle | | public static void shuffle(List list)(Code) | | Moves every element of the List to a random new position in the list.
Parameters:
list - the List to shuffle
throws:
UnsupportedOperationException - when replacing an element in the List is not supported |
| shuffle | | public static void shuffle(List list, Random random)(Code) | | Moves every element of the List to a random new position in the list
using the specified random number generator.
Parameters:
list - the List to shuffle
Parameters:
random - the random number generator
throws:
UnsupportedOperationException - when replacing an element in the List is not supported |
| singleton | | public static Set<E> singleton(E object)(Code) | | Answers a Set containing the specified element. The set cannot be
modified.
Parameters:
object - the element a Set containing the element |
| singletonList | | public static List<E> singletonList(E object)(Code) | | Answers a List containing the specified element. The list cannot be
modified.
Parameters:
object - the element a List containing the element |
| singletonMap | | public static Map<K, V> singletonMap(K key, V value)(Code) | | Answers a Map containing the specified key and value. The map cannot be
modified.
Parameters:
key - the key
Parameters:
value - the value a Map containing the key and value |
| sort | | public static void sort(List<T> list)(Code) | | Sorts the specified List in ascending order.
Parameters:
list - the List to be sorted
throws:
ClassCastException - when an element in the List does not implement Comparable orelements cannot be compared to each other |
| sort | | public static void sort(List<T> list, Comparator<? super T> comparator)(Code) | | Sorts the specified List using the specified Comparator.
Parameters:
list - the List to be sorted
Parameters:
comparator - the Comparator
throws:
ClassCastException - when elements in the List cannot be compared to each otherusing the Comparator |
| swap | | public static void swap(List list, int index1, int index2)(Code) | | Swaps the elements of List list at indices
index1 and index2
Parameters:
list - the List to manipulate on
Parameters:
index1 - int position of the first element to swap with the element inindex2
Parameters:
index2 - int position of the other element
throws:
IndexOutOfBoundsException - if index1 or index2 is out of range of this list |
| synchronizedCollection | | public static Collection<T> synchronizedCollection(Collection<T> collection)(Code) | | Answers a wrapper on the specified Collection which synchronizes all
access to the Collection.
Parameters:
collection - the Collection a synchronized Collection |
| synchronizedList | | public static List<T> synchronizedList(List<T> list)(Code) | | Answers a wrapper on the specified List which synchronizes all access to
the List.
Parameters:
list - the List a synchronized List |
| synchronizedMap | | public static Map<K, V> synchronizedMap(Map<K, V> map)(Code) | | Answers a wrapper on the specified Map which synchronizes all access to
the Map.
Parameters:
map - the Map a synchronized Map |
| synchronizedSet | | public static Set<E> synchronizedSet(Set<E> set)(Code) | | Answers a wrapper on the specified Set which synchronizes all access to
the Set.
Parameters:
set - the Set a synchronized Set |
| synchronizedSortedMap | | public static SortedMap<K, V> synchronizedSortedMap(SortedMap<K, V> map)(Code) | | Answers a wrapper on the specified SortedMap which synchronizes all
access to the SortedMap.
Parameters:
map - the SortedMap a synchronized SortedMap |
| synchronizedSortedSet | | public static SortedSet<E> synchronizedSortedSet(SortedSet<E> set)(Code) | | Answers a wrapper on the specified SortedSet which synchronizes all
access to the SortedSet.
Parameters:
set - the SortedSet a synchronized SortedSet |
| unmodifiableCollection | | public static Collection<E> unmodifiableCollection(Collection<? extends E> collection)(Code) | | Answers a wrapper on the specified Collection which throws an
UnsupportedOperationException whenever an attempt is made
to modify the Collection.
Parameters:
collection - the Collection an unmodifiable Collection |
| unmodifiableList | | public static List<E> unmodifiableList(List<? extends E> list)(Code) | | Answers a wrapper on the specified List which throws an
UnsupportedOperationException whenever an attempt is made
to modify the List.
Parameters:
list - the List an unmodifiable List |
| unmodifiableMap | | public static Map<K, V> unmodifiableMap(Map<? extends K, ? extends V> map)(Code) | | Answers a wrapper on the specified Map which throws an
UnsupportedOperationException whenever an attempt is made
to modify the Map.
Parameters:
map - the Map a unmodifiable Map |
| unmodifiableSet | | public static Set<E> unmodifiableSet(Set<? extends E> set)(Code) | | Answers a wrapper on the specified Set which throws an
UnsupportedOperationException whenever an attempt is made
to modify the Set.
Parameters:
set - the Set a unmodifiable Set |
| unmodifiableSortedMap | | public static SortedMap<K, V> unmodifiableSortedMap(SortedMap<K, ? extends V> map)(Code) | | Answers a wrapper on the specified SortedMap which throws an
UnsupportedOperationException whenever an attempt is made
to modify the SortedMap.
Parameters:
map - the SortedMap a unmodifiable SortedMap |
| unmodifiableSortedSet | | public static SortedSet<E> unmodifiableSortedSet(SortedSet<E> set)(Code) | | Answers a wrapper on the specified SortedSet which throws an
UnsupportedOperationException whenever an attempt is made
to modify the SortedSet.
Parameters:
set - the SortedSet a unmodifiable SortedSet |
|
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