Collections4D (TotalCrossSDK 6.1.0 API)

java.lang.Object
- totalcross.util.Collections4D

```
public class Collections4D
extends java.lang.Object
```
Utility class consisting of static methods that operate on, or return Collections. Contains methods to sort, search, reverse, fill and shuffle Collections, methods to facilitate interoperability with legacy APIs that are unaware of collections, a method to return a list which consists of multiple copies of one element, and methods which "wrap" collections to give them extra properties, such as thread-safety and unmodifiability.
All methods which take a collection throw a NullPointerException if that collection is null. Algorithms which can change a collection may, but are not required, to throw the UnsupportedOperationException that the underlying collection would throw during an attempt at modification. For example, Collections.singleton("").addAll(Collections.EMPTY_SET) does not throw a exception, even though addAll is an unsupported operation on a singleton; the reason for this is that addAll did not attempt to modify the set.

Since:

1.2

See Also:

Collection, Set, List, Map, Arrays

Field Summary

Fields
Modifier and Type	Field and Description
`static java.util.List`	`EMPTY_LIST` An immutable, serializable, empty List, which implements RandomAccess.
`static java.util.Map`	`EMPTY_MAP` An immutable, serializable, empty Map.
`static java.util.Set`	`EMPTY_SET` An immutable, serializable, empty Set.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> boolean`	`addAll(java.util.Collection<? super T> c, T... a)` Adds all the specified elements to the given collection, in a similar way to the `addAll` method of the `Collection`.
`static <T> java.util.Queue<T>`	`asLifoQueue(java.util.Deque<T> deque)` Returns a view of a `Deque` as a stack or LIFO (Last-In-First-Out) `Queue`.
`static <T> int`	`binarySearch(java.util.List<? extends java.lang.Comparable<? super T>> l, T key)` Perform a binary search of a List for a key, using the natural ordering of the elements.
`static <T> int`	`binarySearch(java.util.List<? extends T> l, T key, java.util.Comparator<? super T> c)` Perform a binary search of a List for a key, using a supplied Comparator.
`static <E> java.util.Collection<E>`	`checkedCollection(java.util.Collection<E> c, java.lang.Class<E> type)` Returns a dynamically typesafe view of the given collection, where any modification is first checked to ensure that the type of the new data is appropriate.
`static <E> java.util.List<E>`	`checkedList(java.util.List<E> l, java.lang.Class<E> type)` Returns a dynamically typesafe view of the given list, where any modification is first checked to ensure that the type of the new data is appropriate.
`static <K,V> java.util.Map<K,V>`	`checkedMap(java.util.Map<K,V> m, java.lang.Class<K> keyType, java.lang.Class<V> valueType)` Returns a dynamically typesafe view of the given map, where any modification is first checked to ensure that the type of the new data is appropriate.
`static <E> java.util.Set<E>`	`checkedSet(java.util.Set<E> s, java.lang.Class<E> type)` Returns a dynamically typesafe view of the given set, where any modification is first checked to ensure that the type of the new data is appropriate.
`static <K,V> java.util.SortedMap<K,V>`	`checkedSortedMap(java.util.SortedMap<K,V> m, java.lang.Class<K> keyType, java.lang.Class<V> valueType)` Returns a dynamically typesafe view of the given sorted map, where any modification is first checked to ensure that the type of the new data is appropriate.
`static <E> java.util.SortedSet<E>`	`checkedSortedSet(java.util.SortedSet<E> s, java.lang.Class<E> type)` Returns a dynamically typesafe view of the given sorted set, where any modification is first checked to ensure that the type of the new data is appropriate.
`static <T> void`	`copy(java.util.List<? super T> dest, java.util.List<? extends T> source)` Copy one list to another.
`static boolean`	`disjoint(java.util.Collection<?> c1, java.util.Collection<?> c2)` Returns true if the two specified collections have no elements in common.
`static <T> java.util.List<T>`	`emptyList()` Returns an immutable, serializable parameterized empty list.
`static <K,V> java.util.Map<K,V>`	`emptyMap()` Returns an immutable, serializable parameterized empty map.
`static <T> java.util.Set<T>`	`emptySet()` Returns an immutable, serializable parameterized empty set.
`static <T> java.util.Enumeration<T>`	`enumeration(java.util.Collection<T> c)` Returns an Enumeration over a collection.
`static <T> void`	`fill(java.util.List<? super T> l, T val)` Replace every element of a list with a given value.
`static int`	`frequency(java.util.Collection<?> c, java.lang.Object o)` Returns the frequency of the specified object within the supplied collection.
`static int`	`indexOfSubList(java.util.List<?> source, java.util.List<?> target)` Returns the starting index where the specified sublist first occurs in a larger list, or -1 if there is no matching position.
`static int`	`lastIndexOfSubList(java.util.List<?> source, java.util.List<?> target)` Returns the starting index where the specified sublist last occurs in a larger list, or -1 if there is no matching position.
`static <T> java.util.ArrayList<T>`	`list(java.util.Enumeration<T> e)` Returns an ArrayList holding the elements visited by a given Enumeration.
`static <T extends java.lang.Object & java.lang.Comparable<? super T>> T`	`max(java.util.Collection<? extends T> c)` Find the maximum element in a Collection, according to the natural ordering of the elements.
`static <T> T`	`max(java.util.Collection<? extends T> c, java.util.Comparator<? super T> order)` Find the maximum element in a Collection, according to a specified Comparator.
`static <T extends java.lang.Object & java.lang.Comparable<? super T>> T`	`min(java.util.Collection<? extends T> c)` Find the minimum element in a Collection, according to the natural ordering of the elements.
`static <T> T`	`min(java.util.Collection<? extends T> c, java.util.Comparator<? super T> order)` Find the minimum element in a Collection, according to a specified Comparator.
`static <T> java.util.List<T>`	`nCopies(int n, T o)` Creates an immutable list consisting of the same object repeated n times.
`static <E> java.util.Set<E>`	`newSetFromMap(java.util.Map<E,java.lang.Boolean> map)` Returns a set backed by the supplied map.
`static <T> boolean`	`replaceAll(java.util.List<T> list, T oldval, T newval)` Replace all instances of one object with another in the specified list.
`static void`	`reverse(java.util.List<?> l)` Reverse a given list.
`static <T> java.util.Comparator<T>`	`reverseOrder()` Get a comparator that implements the reverse of natural ordering.
`static <T> java.util.Comparator<T>`	`reverseOrder(java.util.Comparator<T> c)` Get a comparator that implements the reverse of the ordering specified by the given Comparator.
`static void`	`rotate(java.util.List<?> list, int distance)` Rotate the elements in a list by a specified distance.
`static void`	`shuffle(java.util.List<?> l)` Shuffle a list according to a default source of randomness.
`static void`	`shuffle(java.util.List<?> l, java.util.Random r)` Shuffle a list according to a given source of randomness.
`static <T> java.util.Set<T>`	`singleton(T o)` Obtain an immutable Set consisting of a single element.
`static <T> java.util.List<T>`	`singletonList(T o)` Obtain an immutable List consisting of a single element.
`static <K,V> java.util.Map<K,V>`	`singletonMap(K key, V value)` Obtain an immutable Map consisting of a single key-value pair.
`static <T extends java.lang.Comparable<? super T>> void`	`sort(java.util.List<T> l)` Sort a list according to the natural ordering of its elements.
`static <T> void`	`sort(java.util.List<T> l, java.util.Comparator<? super T> c)` Sort a list according to a specified Comparator.
`static void`	`swap(java.util.List<?> l, int i, int j)` Swaps the elements at the specified positions within the list.
`static <T> java.util.Collection<T>`	`synchronizedCollection(java.util.Collection<T> c)` Returns a synchronized (thread-safe) collection wrapper backed by the given collection.
`static <T> java.util.List<T>`	`synchronizedList(java.util.List<T> l)` Returns a synchronized (thread-safe) list wrapper backed by the given list.
`static <K,V> java.util.Map<K,V>`	`synchronizedMap(java.util.Map<K,V> m)` Returns a synchronized (thread-safe) map wrapper backed by the given map.
`static <T> java.util.Set<T>`	`synchronizedSet(java.util.Set<T> s)` Returns a synchronized (thread-safe) set wrapper backed by the given set.
`static <K,V> java.util.SortedMap<K,V>`	`synchronizedSortedMap(java.util.SortedMap<K,V> m)` Returns a synchronized (thread-safe) sorted map wrapper backed by the given map.
`static <T> java.util.SortedSet<T>`	`synchronizedSortedSet(java.util.SortedSet<T> s)` Returns a synchronized (thread-safe) sorted set wrapper backed by the given set.
`static <T> java.util.Collection<T>`	`unmodifiableCollection(java.util.Collection<? extends T> c)` Returns an unmodifiable view of the given collection.
`static <T> java.util.List<T>`	`unmodifiableList(java.util.List<? extends T> l)` Returns an unmodifiable view of the given list.
`static <K,V> java.util.Map<K,V>`	`unmodifiableMap(java.util.Map<? extends K,? extends V> m)` Returns an unmodifiable view of the given map.
`static <T> java.util.Set<T>`	`unmodifiableSet(java.util.Set<? extends T> s)` Returns an unmodifiable view of the given set.
`static <K,V> java.util.SortedMap<K,V>`	`unmodifiableSortedMap(java.util.SortedMap<K,? extends V> m)` Returns an unmodifiable view of the given sorted map.
`static <T> java.util.SortedSet<T>`	`unmodifiableSortedSet(java.util.SortedSet<T> s)` Returns an unmodifiable view of the given sorted set.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - EMPTY_SET
```
public static final java.util.Set EMPTY_SET
```
    An immutable, serializable, empty Set.
  - EMPTY_LIST
```
public static final java.util.List EMPTY_LIST
```
    An immutable, serializable, empty List, which implements RandomAccess.
    
    See Also:
    
    RandomAccess
  - EMPTY_MAP
```
public static final java.util.Map EMPTY_MAP
```
    An immutable, serializable, empty Map.
- Method Detail
  - emptySet
```
public static final <T> java.util.Set<T> emptySet()
```
    Returns an immutable, serializable parameterized empty set. Unlike the constant EMPTY_SET, the set returned by this method is type-safe.
    
    Returns:
    
    an empty parameterized set.
    
    Since:
    
    1.5
  - emptyList
```
public static final <T> java.util.List<T> emptyList()
```
    Returns an immutable, serializable parameterized empty list. Unlike the constant EMPTY_LIST, the list returned by this method is type-safe.
    
    Returns:
    
    an empty parameterized list.
    
    Since:
    
    1.5
  - emptyMap
```
public static final <K,V> java.util.Map<K,V> emptyMap()
```
    Returns an immutable, serializable parameterized empty map. Unlike the constant EMPTY_MAP, the map returned by this method is type-safe.
    
    Returns:
    
    an empty parameterized map.
    
    Since:
    
    1.5
  - binarySearch
```
public static <T> int binarySearch(java.util.List<? extends java.lang.Comparable<? super T>> l,
                                   T key)
```
    Perform a binary search of a List for a key, using the natural ordering of the elements. The list must be sorted (as by the sort() method) - if it is not, the behavior of this method is undefined, and may be an infinite loop. Further, the key must be comparable with every item in the list. If the list contains the key more than once, any one of them may be found.
    This algorithm behaves in log(n) time for RandomAccess lists, and uses a linear search with O(n) link traversals and log(n) comparisons with AbstractSequentialList lists. Note: although the specification allows for an infinite loop if the list is unsorted, it will not happen in this (Classpath) implementation.
    
    Parameters:
    
    l - the list to search (must be sorted)
    
    key - the value to search for
    
    Returns:
    
    the index at which the key was found, or -n-1 if it was not found, where n is the index of the first value higher than key or a.length if there is no such value
    
    Throws:
    
    java.lang.ClassCastException - if key could not be compared with one of the elements of l
    
    java.lang.NullPointerException - if a null element has compareTo called
    
    See Also:
    
    sort(List)
  - binarySearch
```
public static <T> int binarySearch(java.util.List<? extends T> l,
                                   T key,
                                   java.util.Comparator<? super T> c)
```
    Perform a binary search of a List for a key, using a supplied Comparator. The list must be sorted (as by the sort() method with the same Comparator) - if it is not, the behavior of this method is undefined, and may be an infinite loop. Further, the key must be comparable with every item in the list. If the list contains the key more than once, any one of them may be found. If the comparator is null, the elements' natural ordering is used.
    This algorithm behaves in log(n) time for RandomAccess lists, and uses a linear search with O(n) link traversals and log(n) comparisons with AbstractSequentialList lists. Note: although the specification allows for an infinite loop if the list is unsorted, it will not happen in this (Classpath) implementation.
    
    Parameters:
    
    l - the list to search (must be sorted)
    
    key - the value to search for
    
    c - the comparator by which the list is sorted
    
    Returns:
    
    the index at which the key was found, or -n-1 if it was not found, where n is the index of the first value higher than key or a.length if there is no such value
    
    Throws:
    
    java.lang.ClassCastException - if key could not be compared with one of the elements of l
    
    java.lang.NullPointerException - if a null element is compared with natural ordering (only possible when c is null)
    
    See Also:
    
    sort(List, Comparator)
  - copy
```
public static <T> void copy(java.util.List<? super T> dest,
                            java.util.List<? extends T> source)
```
    Copy one list to another. If the destination list is longer than the source list, the remaining elements are unaffected. This method runs in linear time.
    
    Parameters:
    
    dest - the destination list
    
    source - the source list
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - if the destination list is shorter than the source list (the destination will be unmodified)
    
    java.lang.UnsupportedOperationException - if dest.listIterator() does not support the set operation
  - enumeration
```
public static <T> java.util.Enumeration<T> enumeration(java.util.Collection<T> c)
```
    Returns an Enumeration over a collection. This allows interoperability with legacy APIs that require an Enumeration as input.
    
    Parameters:
    
    c - the Collection to iterate over
    
    Returns:
    
    an Enumeration backed by an Iterator over c
  - fill
```
public static <T> void fill(java.util.List<? super T> l,
                            T val)
```
    Replace every element of a list with a given value. This method runs in linear time.
    
    Parameters:
    
    l - the list to fill.
    
    val - the object to vill the list with.
    
    Throws:
    
    java.lang.UnsupportedOperationException - if l.listIterator() does not support the set operation.
  - indexOfSubList
```
public static int indexOfSubList(java.util.List<?> source,
                                 java.util.List<?> target)
```
    Returns the starting index where the specified sublist first occurs in a larger list, or -1 if there is no matching position. If target.size() > source.size(), this returns -1, otherwise this implementation uses brute force, checking for source.sublist(i, i + target.size()).equals(target) for all possible i.
    
    Parameters:
    
    source - the list to search
    
    target - the sublist to search for
    
    Returns:
    
    the index where found, or -1
    
    Since:
    
    1.4
  - lastIndexOfSubList
```
public static int lastIndexOfSubList(java.util.List<?> source,
                                     java.util.List<?> target)
```
    Returns the starting index where the specified sublist last occurs in a larger list, or -1 if there is no matching position. If target.size() > source.size(), this returns -1, otherwise this implementation uses brute force, checking for source.sublist(i, i + target.size()).equals(target) for all possible i.
    
    Parameters:
    
    source - the list to search
    
    target - the sublist to search for
    
    Returns:
    
    the index where found, or -1
    
    Since:
    
    1.4
  - list
```
public static <T> java.util.ArrayList<T> list(java.util.Enumeration<T> e)
```
    Returns an ArrayList holding the elements visited by a given Enumeration. This method exists for interoperability between legacy APIs and the new Collection API.
    
    Parameters:
    
    e - the enumeration to put in a list
    
    Returns:
    
    a list containing the enumeration elements
    
    Since:
    
    1.4
    
    See Also:
    
    ArrayList
  - max
```
public static <T extends java.lang.Object & java.lang.Comparable<? super T>> T max(java.util.Collection<? extends T> c)
```
    Find the maximum element in a Collection, according to the natural ordering of the elements. This implementation iterates over the Collection, so it works in linear time.
    
    Parameters:
    
    c - the Collection to find the maximum element of
    
    Returns:
    
    the maximum element of c
    
    Throws:
    
    java.util.NoSuchElementException - if c is empty
    
    java.lang.ClassCastException - if elements in c are not mutually comparable
    
    java.lang.NullPointerException - if null.compareTo is called
  - max
```
public static <T> T max(java.util.Collection<? extends T> c,
                        java.util.Comparator<? super T> order)
```
    Find the maximum element in a Collection, according to a specified Comparator. This implementation iterates over the Collection, so it works in linear time.
    
    Parameters:
    
    c - the Collection to find the maximum element of
    
    order - the Comparator to order the elements by, or null for natural ordering
    
    Returns:
    
    the maximum element of c
    
    Throws:
    
    java.util.NoSuchElementException - if c is empty
    
    java.lang.ClassCastException - if elements in c are not mutually comparable
    
    java.lang.NullPointerException - if null is compared by natural ordering (only possible when order is null)
  - min
```
public static <T extends java.lang.Object & java.lang.Comparable<? super T>> T min(java.util.Collection<? extends T> c)
```
    Find the minimum element in a Collection, according to the natural ordering of the elements. This implementation iterates over the Collection, so it works in linear time.
    
    Parameters:
    
    c - the Collection to find the minimum element of
    
    Returns:
    
    the minimum element of c
    
    Throws:
    
    java.util.NoSuchElementException - if c is empty
    
    java.lang.ClassCastException - if elements in c are not mutually comparable
    
    java.lang.NullPointerException - if null.compareTo is called
  - min
```
public static <T> T min(java.util.Collection<? extends T> c,
                        java.util.Comparator<? super T> order)
```
    Find the minimum element in a Collection, according to a specified Comparator. This implementation iterates over the Collection, so it works in linear time.
    
    Parameters:
    
    c - the Collection to find the minimum element of
    
    order - the Comparator to order the elements by, or null for natural ordering
    
    Returns:
    
    the minimum element of c
    
    Throws:
    
    java.util.NoSuchElementException - if c is empty
    
    java.lang.ClassCastException - if elements in c are not mutually comparable
    
    java.lang.NullPointerException - if null is compared by natural ordering (only possible when order is null)
  - nCopies
```
public static <T> java.util.List<T> nCopies(int n,
                                            T o)
```
    Creates an immutable list consisting of the same object repeated n times. The returned object is tiny, consisting of only a single reference to the object and a count of the number of elements. It is Serializable, and implements RandomAccess. You can use it in tandem with List.addAll for fast list construction.
    
    Parameters:
    
    n - the number of times to repeat the object
    
    o - the object to repeat
    
    Returns:
    
    a List consisting of n copies of o
    
    Throws:
    
    java.lang.IllegalArgumentException - if n < 0
    
    See Also:
    
    List.addAll(Collection), RandomAccess
  - replaceAll
```
public static <T> boolean replaceAll(java.util.List<T> list,
                                     T oldval,
                                     T newval)
```
    Replace all instances of one object with another in the specified list. The list does not change size. An element e is replaced if oldval == null ? e == null : oldval.equals(e).
    
    Parameters:
    
    list - the list to iterate over
    
    oldval - the element to replace
    
    newval - the new value for the element
    
    Returns:
    
    true if a replacement occurred.
    
    Throws:
    
    java.lang.UnsupportedOperationException - if the list iterator does not allow for the set operation
    
    java.lang.ClassCastException - if newval is of a type which cannot be added to the list
    
    java.lang.IllegalArgumentException - if some other aspect of newval stops it being added to the list
    
    Since:
    
    1.4
  - reverse
```
public static void reverse(java.util.List<?> l)
```
    Reverse a given list. This method works in linear time.
    
    Parameters:
    
    l - the list to reverse
    
    Throws:
    
    java.lang.UnsupportedOperationException - if l.listIterator() does not support the set operation
  - reverseOrder
```
public static <T> java.util.Comparator<T> reverseOrder(java.util.Comparator<T> c)
```
    Get a comparator that implements the reverse of the ordering specified by the given Comparator. If the Comparator is null, this is equivalent to reverseOrder(). The return value of this method is Serializable, if the specified Comparator is either Serializable or null.
    
    Parameters:
    
    c - the comparator to invert
    
    Returns:
    
    a comparator that imposes reverse ordering
    
    Since:
    
    1.5
    
    See Also:
    
    Comparable
  - reverseOrder
```
public static <T> java.util.Comparator<T> reverseOrder()
```
    Get a comparator that implements the reverse of natural ordering. In other words, this sorts Comparable objects opposite of how their compareTo method would sort. This makes it easy to sort into reverse order, by simply passing Collections.reverseOrder() to the sort method. The return value of this method is Serializable.
    
    Returns:
    
    a comparator that imposes reverse natural ordering
    
    See Also:
    
    Comparable
  - rotate
```
public static void rotate(java.util.List<?> list,
                          int distance)
```
    Rotate the elements in a list by a specified distance. After calling this method, the element now at index i was formerly at index (i - distance) mod list.size(). The list size is unchanged.
    For example, suppose a list contains [t, a, n, k, s]. After either Collections.rotate(l, 4) or Collections.rotate(l, -1), the new contents are [s, t, a, n, k]. This can be applied to sublists to rotate just a portion of the list. For example, to move element a forward two positions in the original example, use Collections.rotate(l.subList(1, 3+1), -1), which will result in [t, n, k, a, s].
    If the list is small or implements RandomAccess, the implementation exchanges the first element to its destination, then the displaced element, and so on until a circuit has been completed. The process is repeated if needed on the second element, and so forth, until all elements have been swapped. For large non-random lists, the implementation breaks the list into two sublists at index -distance mod size, calls reverse(List) on the pieces, then reverses the overall list.
    
    Parameters:
    
    list - the list to rotate
    
    distance - the distance to rotate by; unrestricted in value
    
    Throws:
    
    java.lang.UnsupportedOperationException - if the list does not support set
    
    Since:
    
    1.4
  - shuffle
```
public static void shuffle(java.util.List<?> l)
```
    Shuffle a list according to a default source of randomness. The algorithm used iterates backwards over the list, swapping each element with an element randomly selected from the elements in positions less than or equal to it (using r.nextInt(int)).
    This algorithm would result in a perfectly fair shuffle (that is, each element would have an equal chance of ending up in any position) if r were a perfect source of randomness. In practice the results are merely very close to perfect.
    This method operates in linear time. To do this on large lists which do not implement RandomAccess, a temporary array is used to acheive this speed, since it would be quadratic access otherwise.
    
    Parameters:
    
    l - the list to shuffle
    
    Throws:
    
    java.lang.UnsupportedOperationException - if l.listIterator() does not support the set operation
  - shuffle
```
public static void shuffle(java.util.List<?> l,
                           java.util.Random r)
```
    Shuffle a list according to a given source of randomness. The algorithm used iterates backwards over the list, swapping each element with an element randomly selected from the elements in positions less than or equal to it (using r.nextInt(int)).
    This algorithm would result in a perfectly fair shuffle (that is, each element would have an equal chance of ending up in any position) if r were a perfect source of randomness. In practise (eg if r = new Random()) the results are merely very close to perfect.
    This method operates in linear time. To do this on large lists which do not implement RandomAccess, a temporary array is used to acheive this speed, since it would be quadratic access otherwise.
    
    Parameters:
    
    l - the list to shuffle
    
    r - the source of randomness to use for the shuffle
    
    Throws:
    
    java.lang.UnsupportedOperationException - if l.listIterator() does not support the set operation
  - frequency
```
public static int frequency(java.util.Collection<?> c,
                            java.lang.Object o)
```
    Returns the frequency of the specified object within the supplied collection. The frequency represents the number of occurrences of elements within the collection which return true when compared with the object using the equals method.
    
    Parameters:
    
    c - the collection to scan for occurrences of the object.
    
    o - the object to locate occurrances of within the collection.
    
    Throws:
    
    java.lang.NullPointerException - if the collection is null.
    
    Since:
    
    1.5
  - addAll
```
public static <T> boolean addAll(java.util.Collection<? super T> c,
                                 T... a)
```
    Adds all the specified elements to the given collection, in a similar way to the addAll method of the Collection. However, this is a variable argument method which allows the new elements to be specified individually or in array form, as opposed to the list required by the collection's addAll method. This has benefits in both simplicity (multiple elements can be added without having to be wrapped inside a grouping structure) and efficiency (as a redundant list doesn't have to be created to add an individual set of elements or an array).
    
    Parameters:
    
    c - the collection to which the elements should be added.
    
    a - the elements to be added to the collection.
    
    Returns:
    
    true if the collection changed its contents as a result.
    
    Throws:
    
    java.lang.UnsupportedOperationException - if the collection does not support addition.
    
    java.lang.NullPointerException - if one or more elements in a are null, and the collection does not allow null elements. This exception is also thrown if either c or a are null.
    
    java.lang.IllegalArgumentException - if the collection won't allow an element to be added for some other reason.
    
    Since:
    
    1.5
  - disjoint
```
public static boolean disjoint(java.util.Collection<?> c1,
                               java.util.Collection<?> c2)
```
    Returns true if the two specified collections have no elements in common. This method may give unusual results if one or both collections use a non-standard equality test. In the trivial case of comparing a collection with itself, this method returns true if, and only if, the collection is empty.
    
    Parameters:
    
    c1 - the first collection to compare.
    
    c2 - the second collection to compare.
    
    Returns:
    
    true if the collections are disjoint.
    
    Throws:
    
    java.lang.NullPointerException - if either collection is null.
    
    Since:
    
    1.5
  - singleton
```
public static <T> java.util.Set<T> singleton(T o)
```
    Obtain an immutable Set consisting of a single element. The return value of this method is Serializable.
    
    Parameters:
    
    o - the single element
    
    Returns:
    
    an immutable Set containing only o
  - singletonList
```
public static <T> java.util.List<T> singletonList(T o)
```
    Obtain an immutable List consisting of a single element. The return value of this method is Serializable, and implements RandomAccess.
    
    Parameters:
    
    o - the single element
    
    Returns:
    
    an immutable List containing only o
    
    Since:
    
    1.3
    
    See Also:
    
    RandomAccess
  - singletonMap
```
public static <K,V> java.util.Map<K,V> singletonMap(K key,
                                                    V value)
```
    Obtain an immutable Map consisting of a single key-value pair. The return value of this method is Serializable.
    
    Parameters:
    
    key - the single key
    
    value - the single value
    
    Returns:
    
    an immutable Map containing only the single key-value pair
    
    Since:
    
    1.3
  - sort
```
public static <T extends java.lang.Comparable<? super T>> void sort(java.util.List<T> l)
```
    Sort a list according to the natural ordering of its elements. The list must be modifiable, but can be of fixed size. The sort algorithm is precisely that used by Arrays.sort(Object[]), which offers guaranteed nlog(n) performance. This implementation dumps the list into an array, sorts the array, and then iterates over the list setting each element from the array.
    
    Parameters:
    
    l - the List to sort (null not permitted)
    
    Throws:
    
    java.lang.ClassCastException - if some items are not mutually comparable
    
    java.lang.UnsupportedOperationException - if the List is not modifiable
    
    java.lang.NullPointerException - if the list is null, or contains some element that is null.
    
    See Also:
    
    Arrays.sort(Object[])
  - sort
```
public static <T> void sort(java.util.List<T> l,
                            java.util.Comparator<? super T> c)
```
    Sort a list according to a specified Comparator. The list must be modifiable, but can be of fixed size. The sort algorithm is precisely that used by Arrays.sort(Object[], Comparator), which offers guaranteed nlog(n) performance. This implementation dumps the list into an array, sorts the array, and then iterates over the list setting each element from the array.
    
    Parameters:
    
    l - the List to sort (null not permitted)
    
    c - the Comparator specifying the ordering for the elements, or null for natural ordering
    
    Throws:
    
    java.lang.ClassCastException - if c will not compare some pair of items
    
    java.lang.UnsupportedOperationException - if the List is not modifiable
    
    java.lang.NullPointerException - if the List is null or null is compared by natural ordering (only possible when c is null)
    
    See Also:
    
    Arrays.sort(Object[], Comparator)
  - swap
```
public static void swap(java.util.List<?> l,
                        int i,
                        int j)
```
    Swaps the elements at the specified positions within the list. Equal positions have no effect.
    
    Parameters:
    
    l - the list to work on
    
    i - the first index to swap
    
    j - the second index
    
    Throws:
    
    java.lang.UnsupportedOperationException - if list.set is not supported
    
    java.lang.IndexOutOfBoundsException - if either i or j is < 0 or >= list.size()
    
    Since:
    
    1.4
  - synchronizedCollection
```
public static <T> java.util.Collection<T> synchronizedCollection(java.util.Collection<T> c)
```
    Returns a synchronized (thread-safe) collection wrapper backed by the given collection. Notice that element access through the iterators is thread-safe, but if the collection can be structurally modified (adding or removing elements) then you should synchronize around the iteration to avoid non-deterministic behavior:
```
 Collection c = Collections.synchronizedCollection(new Collection(...));
 ...
 synchronized (c)
   {
     Iterator i = c.iterator();
     while (i.hasNext())
       foo(i.next());
   }
 
```
    Since the collection might be a List or a Set, and those have incompatible equals and hashCode requirements, this relies on Object's implementation rather than passing those calls on to the wrapped collection. The returned Collection implements Serializable, but can only be serialized if the collection it wraps is likewise Serializable.
    Parameters:
    
    c - the collection to wrap
    
    Returns:
    
    a synchronized view of the collection
  - synchronizedList
```
public static <T> java.util.List<T> synchronizedList(java.util.List<T> l)
```
    Returns a synchronized (thread-safe) list wrapper backed by the given list. Notice that element access through the iterators is thread-safe, but if the list can be structurally modified (adding or removing elements) then you should synchronize around the iteration to avoid non-deterministic behavior:
```
 List l = Collections.synchronizedList(new List(...));
 ...
 synchronized (l)
   {
     Iterator i = l.iterator();
     while (i.hasNext())
       foo(i.next());
   }
 
```
    The returned List implements Serializable, but can only be serialized if the list it wraps is likewise Serializable. In addition, if the wrapped list implements RandomAccess, this does too.
    Parameters:
    
    l - the list to wrap
    
    Returns:
    
    a synchronized view of the list
    
    See Also:
    
    RandomAccess
  - synchronizedMap
```
public static <K,V> java.util.Map<K,V> synchronizedMap(java.util.Map<K,V> m)
```
    Returns a synchronized (thread-safe) map wrapper backed by the given map. Notice that element access through the collection views and their iterators are thread-safe, but if the map can be structurally modified (adding or removing elements) then you should synchronize around the iteration to avoid non-deterministic behavior:
```
 Map m = Collections.synchronizedMap(new Map(...));
 ...
 Set s = m.keySet(); // safe outside a synchronized block
 synchronized (m) // synch on m, not s
   {
     Iterator i = s.iterator();
     while (i.hasNext())
       foo(i.next());
   }
 
```
    The returned Map implements Serializable, but can only be serialized if the map it wraps is likewise Serializable.
    Parameters:
    
    m - the map to wrap
    
    Returns:
    
    a synchronized view of the map
  - synchronizedSet
```
public static <T> java.util.Set<T> synchronizedSet(java.util.Set<T> s)
```
    Returns a synchronized (thread-safe) set wrapper backed by the given set. Notice that element access through the iterator is thread-safe, but if the set can be structurally modified (adding or removing elements) then you should synchronize around the iteration to avoid non-deterministic behavior:
```
 Set s = Collections.synchronizedSet(new Set(...));
 ...
 synchronized (s)
   {
     Iterator i = s.iterator();
     while (i.hasNext())
       foo(i.next());
   }
 
```
    The returned Set implements Serializable, but can only be serialized if the set it wraps is likewise Serializable.
    Parameters:
    
    s - the set to wrap
    
    Returns:
    
    a synchronized view of the set
  - synchronizedSortedMap
```
public static <K,V> java.util.SortedMap<K,V> synchronizedSortedMap(java.util.SortedMap<K,V> m)
```
    Returns a synchronized (thread-safe) sorted map wrapper backed by the given map. Notice that element access through the collection views, subviews, and their iterators are thread-safe, but if the map can be structurally modified (adding or removing elements) then you should synchronize around the iteration to avoid non-deterministic behavior:
```
 SortedMap m = Collections.synchronizedSortedMap(new SortedMap(...));
 ...
 Set s = m.keySet(); // safe outside a synchronized block
 SortedMap m2 = m.headMap(foo); // safe outside a synchronized block
 Set s2 = m2.keySet(); // safe outside a synchronized block
 synchronized (m) // synch on m, not m2, s or s2
   {
     Iterator i = s.iterator();
     while (i.hasNext())
       foo(i.next());
     i = s2.iterator();
     while (i.hasNext())
       bar(i.next());
   }
 
```
    The returned SortedMap implements Serializable, but can only be serialized if the map it wraps is likewise Serializable.
    Parameters:
    
    m - the sorted map to wrap
    
    Returns:
    
    a synchronized view of the sorted map
  - synchronizedSortedSet
```
public static <T> java.util.SortedSet<T> synchronizedSortedSet(java.util.SortedSet<T> s)
```
    Returns a synchronized (thread-safe) sorted set wrapper backed by the given set. Notice that element access through the iterator and through subviews are thread-safe, but if the set can be structurally modified (adding or removing elements) then you should synchronize around the iteration to avoid non-deterministic behavior:
```
 SortedSet s = Collections.synchronizedSortedSet(new SortedSet(...));
 ...
 SortedSet s2 = s.headSet(foo); // safe outside a synchronized block
 synchronized (s) // synch on s, not s2
   {
     Iterator i = s2.iterator();
     while (i.hasNext())
       foo(i.next());
   }
 
```
    The returned SortedSet implements Serializable, but can only be serialized if the set it wraps is likewise Serializable.
    Parameters:
    
    s - the sorted set to wrap
    
    Returns:
    
    a synchronized view of the sorted set
  - unmodifiableCollection
```
public static <T> java.util.Collection<T> unmodifiableCollection(java.util.Collection<? extends T> c)
```
    Returns an unmodifiable view of the given collection. This allows "read-only" access, although changes in the backing collection show up in this view. Attempts to modify the collection directly or via iterators will fail with UnsupportedOperationException. Although this view prevents changes to the structure of the collection and its elements, the values referenced by the objects in the collection can still be modified.
    Since the collection might be a List or a Set, and those have incompatible equals and hashCode requirements, this relies on Object's implementation rather than passing those calls on to the wrapped collection. The returned Collection implements Serializable, but can only be serialized if the collection it wraps is likewise Serializable.
    
    Parameters:
    
    c - the collection to wrap
    
    Returns:
    
    a read-only view of the collection
  - unmodifiableList
```
public static <T> java.util.List<T> unmodifiableList(java.util.List<? extends T> l)
```
    Returns an unmodifiable view of the given list. This allows "read-only" access, although changes in the backing list show up in this view. Attempts to modify the list directly, via iterators, or via sublists, will fail with UnsupportedOperationException. Although this view prevents changes to the structure of the list and its elements, the values referenced by the objects in the list can still be modified.
    The returned List implements Serializable, but can only be serialized if the list it wraps is likewise Serializable. In addition, if the wrapped list implements RandomAccess, this does too.
    
    Parameters:
    
    l - the list to wrap
    
    Returns:
    
    a read-only view of the list
    
    See Also:
    
    RandomAccess
  - unmodifiableMap
```
public static <K,V> java.util.Map<K,V> unmodifiableMap(java.util.Map<? extends K,? extends V> m)
```
    Returns an unmodifiable view of the given map. This allows "read-only" access, although changes in the backing map show up in this view. Attempts to modify the map directly, or via collection views or their iterators will fail with UnsupportedOperationException. Although this view prevents changes to the structure of the map and its entries, the values referenced by the objects in the map can still be modified.
    The returned Map implements Serializable, but can only be serialized if the map it wraps is likewise Serializable.
    
    Parameters:
    
    m - the map to wrap
    
    Returns:
    
    a read-only view of the map
  - unmodifiableSet
```
public static <T> java.util.Set<T> unmodifiableSet(java.util.Set<? extends T> s)
```
    Returns an unmodifiable view of the given set. This allows "read-only" access, although changes in the backing set show up in this view. Attempts to modify the set directly or via iterators will fail with UnsupportedOperationException. Although this view prevents changes to the structure of the set and its entries, the values referenced by the objects in the set can still be modified.
    The returned Set implements Serializable, but can only be serialized if the set it wraps is likewise Serializable.
    
    Parameters:
    
    s - the set to wrap
    
    Returns:
    
    a read-only view of the set
  - unmodifiableSortedMap
```
public static <K,V> java.util.SortedMap<K,V> unmodifiableSortedMap(java.util.SortedMap<K,? extends V> m)
```
    Returns an unmodifiable view of the given sorted map. This allows "read-only" access, although changes in the backing map show up in this view. Attempts to modify the map directly, via subviews, via collection views, or iterators, will fail with UnsupportedOperationException. Although this view prevents changes to the structure of the map and its entries, the values referenced by the objects in the map can still be modified.
    The returned SortedMap implements Serializable, but can only be serialized if the map it wraps is likewise Serializable.
    
    Parameters:
    
    m - the map to wrap
    
    Returns:
    
    a read-only view of the map
  - unmodifiableSortedSet
```
public static <T> java.util.SortedSet<T> unmodifiableSortedSet(java.util.SortedSet<T> s)
```
    Returns an unmodifiable view of the given sorted set. This allows "read-only" access, although changes in the backing set show up in this view. Attempts to modify the set directly, via subsets, or via iterators, will fail with UnsupportedOperationException. Although this view prevents changes to the structure of the set and its entries, the values referenced by the objects in the set can still be modified.
    The returns SortedSet implements Serializable, but can only be serialized if the set it wraps is likewise Serializable.
    
    Parameters:
    
    s - the set to wrap
    
    Returns:
    
    a read-only view of the set
  - checkedCollection
```
public static <E> java.util.Collection<E> checkedCollection(java.util.Collection<E> c,
                                                            java.lang.Class<E> type)
```
    Returns a dynamically typesafe view of the given collection, where any modification is first checked to ensure that the type of the new data is appropriate. Although the addition of generics and parametrically-typed collections prevents an incorrect type of element being added to a collection at compile-time, via static type checking, this can be overridden by casting. In contrast, wrapping the collection within a dynamically-typesafe wrapper, using this and associated methods, guarantees that the collection will only contain elements of an appropriate type (provided it only contains such at the type of wrapping, and all subsequent access is via the wrapper). This can be useful for debugging the cause of a ClassCastException caused by erroneous casting, or for protecting collections from corruption by external libraries.
    
    Since the collection might be a List or a Set, and those have incompatible equals and hashCode requirements, this relies on Object's implementation rather than passing those calls on to the wrapped collection. The returned Collection implements Serializable, but can only be serialized if the collection it wraps is likewise Serializable.
    
    Parameters:
    
    c - the collection to wrap in a dynamically typesafe wrapper
    
    type - the type of elements the collection should hold.
    
    Returns:
    
    a dynamically typesafe view of the collection.
    
    Since:
    
    1.5
  - checkedList
```
public static <E> java.util.List<E> checkedList(java.util.List<E> l,
                                                java.lang.Class<E> type)
```
    Returns a dynamically typesafe view of the given list, where any modification is first checked to ensure that the type of the new data is appropriate. Although the addition of generics and parametrically-typed collections prevents an incorrect type of element being added to a collection at compile-time, via static type checking, this can be overridden by casting. In contrast, wrapping the collection within a dynamically-typesafe wrapper, using this and associated methods, guarantees that the collection will only contain elements of an appropriate type (provided it only contains such at the type of wrapping, and all subsequent access is via the wrapper). This can be useful for debugging the cause of a ClassCastException caused by erroneous casting, or for protecting collections from corruption by external libraries.
    
    The returned List implements Serializable, but can only be serialized if the list it wraps is likewise Serializable. In addition, if the wrapped list implements RandomAccess, this does too.
    
    Parameters:
    
    l - the list to wrap
    
    type - the type of the elements within the checked list.
    
    Returns:
    
    a dynamically typesafe view of the list
    
    See Also:
    
    RandomAccess
  - checkedMap
```
public static <K,V> java.util.Map<K,V> checkedMap(java.util.Map<K,V> m,
                                                  java.lang.Class<K> keyType,
                                                  java.lang.Class<V> valueType)
```
    Returns a dynamically typesafe view of the given map, where any modification is first checked to ensure that the type of the new data is appropriate. Although the addition of generics and parametrically-typed collections prevents an incorrect type of element being added to a collection at compile-time, via static type checking, this can be overridden by casting. In contrast, wrapping the collection within a dynamically-typesafe wrapper, using this and associated methods, guarantees that the collection will only contain elements of an appropriate type (provided it only contains such at the type of wrapping, and all subsequent access is via the wrapper). This can be useful for debugging the cause of a ClassCastException caused by erroneous casting, or for protecting collections from corruption by external libraries.
    
    The returned Map implements Serializable, but can only be serialized if the map it wraps is likewise Serializable.
    
    Parameters:
    
    m - the map to wrap
    
    keyType - the dynamic type of the map's keys.
    
    valueType - the dynamic type of the map's values.
    
    Returns:
    
    a dynamically typesafe view of the map
  - checkedSet
```
public static <E> java.util.Set<E> checkedSet(java.util.Set<E> s,
                                              java.lang.Class<E> type)
```
    Returns a dynamically typesafe view of the given set, where any modification is first checked to ensure that the type of the new data is appropriate. Although the addition of generics and parametrically-typed collections prevents an incorrect type of element being added to a collection at compile-time, via static type checking, this can be overridden by casting. In contrast, wrapping the collection within a dynamically-typesafe wrapper, using this and associated methods, guarantees that the collection will only contain elements of an appropriate type (provided it only contains such at the type of wrapping, and all subsequent access is via the wrapper). This can be useful for debugging the cause of a ClassCastException caused by erroneous casting, or for protecting collections from corruption by external libraries.
    
    The returned Set implements Serializable, but can only be serialized if the set it wraps is likewise Serializable.
    
    Parameters:
    
    s - the set to wrap.
    
    type - the type of the elements within the checked list.
    
    Returns:
    
    a dynamically typesafe view of the set
  - checkedSortedMap
```
public static <K,V> java.util.SortedMap<K,V> checkedSortedMap(java.util.SortedMap<K,V> m,
                                                              java.lang.Class<K> keyType,
                                                              java.lang.Class<V> valueType)
```
    Returns a dynamically typesafe view of the given sorted map, where any modification is first checked to ensure that the type of the new data is appropriate. Although the addition of generics and parametrically-typed collections prevents an incorrect type of element being added to a collection at compile-time, via static type checking, this can be overridden by casting. In contrast, wrapping the collection within a dynamically-typesafe wrapper, using this and associated methods, guarantees that the collection will only contain elements of an appropriate type (provided it only contains such at the type of wrapping, and all subsequent access is via the wrapper). This can be useful for debugging the cause of a ClassCastException caused by erroneous casting, or for protecting collections from corruption by external libraries.
    
    The returned SortedMap implements Serializable, but can only be serialized if the map it wraps is likewise Serializable.
    
    Parameters:
    
    m - the map to wrap.
    
    keyType - the dynamic type of the map's keys.
    
    valueType - the dynamic type of the map's values.
    
    Returns:
    
    a dynamically typesafe view of the map
  - checkedSortedSet
```
public static <E> java.util.SortedSet<E> checkedSortedSet(java.util.SortedSet<E> s,
                                                          java.lang.Class<E> type)
```
    Returns a dynamically typesafe view of the given sorted set, where any modification is first checked to ensure that the type of the new data is appropriate. Although the addition of generics and parametrically-typed collections prevents an incorrect type of element being added to a collection at compile-time, via static type checking, this can be overridden by casting. In contrast, wrapping the collection within a dynamically-typesafe wrapper, using this and associated methods, guarantees that the collection will only contain elements of an appropriate type (provided it only contains such at the type of wrapping, and all subsequent access is via the wrapper). This can be useful for debugging the cause of a ClassCastException caused by erroneous casting, or for protecting collections from corruption by external libraries.
    
    The returned SortedSet implements Serializable, but can only be serialized if the set it wraps is likewise Serializable.
    
    Parameters:
    
    s - the set to wrap.
    
    type - the type of the set's elements.
    
    Returns:
    
    a dynamically typesafe view of the set
  - asLifoQueue
```
public static <T> java.util.Queue<T> asLifoQueue(java.util.Deque<T> deque)
```
    Returns a view of a Deque as a stack or LIFO (Last-In-First-Out) Queue. Each call to the LIFO queue corresponds to one equivalent method call to the underlying deque, with the exception of Collection.addAll(Collection), which is emulated by a series of Deque#push(E) calls.
    
    Parameters:
    
    deque - the deque to convert to a LIFO queue.
    
    Returns:
    
    a LIFO queue.
    
    Since:
    
    1.6
  - newSetFromMap
```
public static <E> java.util.Set<E> newSetFromMap(java.util.Map<E,java.lang.Boolean> map)
```
    Returns a set backed by the supplied map. The resulting set has the same performance, concurrency and ordering characteristics as the original map. The supplied map must be empty and should not be used after the set is created. Each call to the set corresponds to one equivalent method call to the underlying map, with the exception of Set.addAll(Collection) which is emulated by a series of calls to put.
    
    Parameters:
    
    map - the map to convert to a set.
    
    Returns:
    
    a set backed by the supplied map.
    
    Throws:
    
    java.lang.IllegalArgumentException - if the map is not empty.
    
    Since:
    
    1.6

Class Collections4D

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

EMPTY_SET

EMPTY_LIST

EMPTY_MAP

Method Detail

emptySet

emptyList

emptyMap

binarySearch

binarySearch

copy

enumeration

fill

indexOfSubList

lastIndexOfSubList

list

max

max

min

min

nCopies

replaceAll

reverse

reverseOrder

reverseOrder

rotate

shuffle

shuffle

frequency

addAll

disjoint

singleton

singletonList

singletonMap

sort

sort

swap

synchronizedCollection

synchronizedList

synchronizedMap

synchronizedSet

synchronizedSortedMap

synchronizedSortedSet

unmodifiableCollection

unmodifiableList

unmodifiableMap

unmodifiableSet

unmodifiableSortedMap

unmodifiableSortedSet

checkedCollection

checkedList

checkedMap

checkedSet

checkedSortedMap

checkedSortedSet

asLifoQueue

newSetFromMap