Modifier and Type | Method and Description |
---|---|
static <E> List |
asList(E first, E[] rest)
Returns an unmodifiable list containing the specified first element and backed by the specified array of additional elements.
|
static <E> List |
asList(E first, E second, E[] rest)
Returns an unmodifiable list containing the specified first and second element, and backed by the specified array of additional elements.
|
static <B> List |
cartesianProduct(List
Returns every possible list that can be formed by choosing one element from each of the given lists in order; the "n-ary
Cartesian product" of the lists.
|
static <B> List |
cartesianProduct(List
Returns every possible list that can be formed by choosing one element from each of the given lists in order; the "n-ary
Cartesian product" of the lists.
|
static List |
charactersOf(CharSequence
Returns a view of the specified
CharSequence as a
List<Character> , viewing
sequence as a sequence of Unicode code units.
|
static ImmutableList |
charactersOf(String
Returns a view of the specified string as an immutable list of
Character values.
|
static <E> ArrayList |
newArrayList()
Creates a
mutable, empty
ArrayList instance (for Java 6 and earlier).
|
static <E> ArrayList |
newArrayList(E... elements)
Creates a
mutable
ArrayList instance containing the given elements.
|
static <E> ArrayList |
newArrayList(Iterable
Creates a
mutable
ArrayList instance containing the given elements; a very thin shortcut for creating an empty list then calling
Iterables .
|
static <E> ArrayList |
newArrayList(Iterator
Creates a
mutable
ArrayList instance containing the given elements; a very thin shortcut for creating an empty list and then calling
Iterators .
|
static <E> ArrayList |
newArrayListWithCapacity(int initialArraySize)
Creates an
ArrayList instance backed by an array with the specified initial size; simply delegates to
ArrayList .
|
static <E> ArrayList |
newArrayListWithExpectedSize(int estimatedSize)
Creates an
ArrayList instance to hold
estimatedSize elements,
plus an unspecified amount of padding; you almost certainly mean to call
newArrayListWithCapacity(int) (see that method for further advice on usage).
|
static <E> CopyOnWriteArrayList |
newCopyOnWriteArrayList()
Creates an empty
CopyOnWriteArrayList instance.
|
static <E> CopyOnWriteArrayList |
newCopyOnWriteArrayList(Iterable
Creates a
CopyOnWriteArrayList instance containing the given elements.
|
static <E> LinkedList |
newLinkedList()
Creates a
mutable, empty
LinkedList instance (for Java 6 and earlier).
|
static <E> LinkedList |
newLinkedList(Iterable
Creates a
mutable
LinkedList instance containing the given elements; a very thin shortcut for creating an empty list then calling
Iterables .
|
static <T> List |
partition(List
Returns consecutive
sublists of a list, each of the same size (the final list may be smaller).
|
static <T> List |
reverse(List
Returns a reversed view of the specified list.
|
static <F |
transform(List
Returns a list that applies
function to each element of
fromList .
|
@GwtCompatible(serializable=true) public static <E> ArrayList<E> newArrayList()
ArrayList
instance (for Java 6 and earlier).
Note: if mutability is not required, use ImmutableList
instead.
Note for Java 7 and later: this method is now unnecessary and should be treated as deprecated. Instead, use the ArrayList
constructor directly, taking advantage of the new "diamond" syntax.
@GwtCompatible(serializable=true) public static <E> ArrayList<E> newArrayList(E... elements)
ArrayList
instance containing the given elements.
Note: essentially the only reason to use this method is when you will need to add or remove elements later. Otherwise, for non-null elements use ImmutableList
(for varargs) or ImmutableList
(for an array) instead. If any elements might be null, or you need support for List
, use Arrays
.
Note that even when you do need the ability to add or remove, this method provides only a tiny bit of syntactic sugar for newArrayList(
asList
(...))
, or for creating an empty list then calling Collections
. This method is not actually very useful and will likely be deprecated in the future.
@GwtCompatible(serializable=true) public static <E> ArrayList<E> newArrayList(Iterable <? extends E> elements)
ArrayList
instance containing the given elements; a very thin shortcut for creating an empty list then calling
Iterables.addAll(java.util.Collection<T>, java.lang.Iterable<? extends T>)
.
Note: if mutability is not required and the elements are non-null, use ImmutableList
instead. (Or, change elements
to be a FluentIterable
and call elements.toList()
.)
Note for Java 7 and later: if elements
is a Collection
, you don't need this method. Use the ArrayList
constructor directly, taking advantage of the new "diamond" syntax.
@GwtCompatible(serializable=true) public static <E> ArrayList<E> newArrayList(Iterator <? extends E> elements)
ArrayList
instance containing the given elements; a very thin shortcut for creating an empty list and then calling
Iterators.addAll(java.util.Collection<T>, java.util.Iterator<? extends T>)
.
Note: if mutability is not required and the elements are non-null, use ImmutableList
instead.
@GwtCompatible(serializable=true) public static <E> ArrayList<E> newArrayListWithCapacity(int initialArraySize)
ArrayList
instance backed by an array with the specified initial size; simply delegates to
ArrayList.ArrayList(int)
.
Note for Java 7 and later: this method is now unnecessary and should be treated as deprecated. Instead, use new
ArrayList
<>(int)
directly, taking advantage of the new "diamond" syntax. (Unlike here, there is no risk of overload ambiguity, since the ArrayList
constructors very wisely did not accept varargs.)
initialArraySize
- the exact size of the initial backing array for the returned array list (
ArrayList
documentation calls this value the "capacity")
ArrayList
which is guaranteed not to resize itself unless its size reaches
initialArraySize + 1
IllegalArgumentException
- if
initialArraySize
is negative
@GwtCompatible(serializable=true) public static <E> ArrayList<E> newArrayListWithExpectedSize(int estimatedSize)
ArrayList
instance to hold
estimatedSize
elements,
plus an unspecified amount of padding; you almost certainly mean to call
newArrayListWithCapacity(int)
(see that method for further advice on usage).
Note: This method will soon be deprecated. Even in the rare case that you do want some amount of padding, it's best if you choose your desired amount explicitly.
estimatedSize
- an estimate of the eventual
List.size()
of the new list
ArrayList
, sized appropriately to hold the estimated number of elements
IllegalArgumentException
- if
estimatedSize
is negative
@GwtCompatible(serializable=true) public static <E> LinkedList<E> newLinkedList()
LinkedList
instance (for Java 6 and earlier).
Note: if you won't be adding any elements to the list, use ImmutableList
instead.
Performance note: ArrayList
and ArrayDeque
consistently outperform LinkedList
except in certain rare and specific situations. Unless you have spent a lot of time benchmarking your specific needs, use one of those instead.
Note for Java 7 and later: this method is now unnecessary and should be treated as deprecated. Instead, use the LinkedList
constructor directly, taking advantage of the new "diamond" syntax.
@GwtCompatible(serializable=true) public static <E> LinkedList<E> newLinkedList(Iterable <? extends E> elements)
LinkedList
instance containing the given elements; a very thin shortcut for creating an empty list then calling
Iterables.addAll(java.util.Collection<T>, java.lang.Iterable<? extends T>)
.
Note: if mutability is not required and the elements are non-null, use ImmutableList
instead. (Or, change elements
to be a FluentIterable
and call elements.toList()
.)
Performance note: ArrayList
and ArrayDeque
consistently outperform LinkedList
except in certain rare and specific situations. Unless you have spent a lot of time benchmarking your specific needs, use one of those instead.
Note for Java 7 and later: if elements
is a Collection
, you don't need this method. Use the LinkedList
constructor directly, taking advantage of the new "diamond" syntax.
@GwtIncompatible(value="CopyOnWriteArrayList") public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList()
CopyOnWriteArrayList
instance.
Note: if you need an immutable empty List
, use Collections
instead.
CopyOnWriteArrayList
@GwtIncompatible(value="CopyOnWriteArrayList") public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(Iterable <? extends E> elements)
CopyOnWriteArrayList
instance containing the given elements.
elements
- the elements that the list should contain, in order
CopyOnWriteArrayList
containing those elements
public static <E> List<E> asList(E first, E[] rest)
rest
array will be reflected in the returned list. Unlike
Arrays.asList(T...)
, the returned list is unmodifiable.
This is useful when a varargs method needs to use a signature such as (Foo firstFoo, Foo... moreFoos)
, in order to avoid overload ambiguity or to enforce a minimum argument count.
The returned list is serializable and implements RandomAccess
.
first
- the first element
rest
- an array of additional elements, possibly empty
public static <E> List<E> asList(E first, E second, E[] rest)
rest
array will be reflected in the returned list. Unlike
Arrays.asList(T...)
, the returned list is unmodifiable.
This is useful when a varargs method needs to use a signature such as (Foo firstFoo, Foo secondFoo, Foo... moreFoos)
, in order to avoid overload ambiguity or to enforce a minimum argument count.
The returned list is serializable and implements RandomAccess
.
first
- the first element
second
- the second element
rest
- an array of additional elements, possibly empty
public static <B> List<List <B>> cartesianProduct(List <? extends List <? extends B>> lists)
Lists.cartesianProduct(ImmutableList.of( ImmutableList.of(1, 2), ImmutableList.of("A", "B", "C")))
returns a list containing six lists in the following order:
ImmutableList.of(1, "A")
ImmutableList.of(1, "B")
ImmutableList.of(1, "C")
ImmutableList.of(2, "A")
ImmutableList.of(2, "B")
ImmutableList.of(2, "C")
The result is guaranteed to be in the "traditional", lexicographical order for Cartesian products that you would get from nesting for loops:
for (B b0 : lists.get(0)) { for (B b1 : lists.get(1)) { ... ImmutableList<B> tuple = ImmutableList.of(b0, b1, ...); // operate on tuple } }
Note that if any input list is empty, the Cartesian product will also be empty. If no lists at all are provided (an empty list), the resulting Cartesian product has one element, an empty list (counter-intuitive, but mathematically consistent).
Performance notes: while the cartesian product of lists of size m, n, p
is a list of size m x n x p
, its actual memory consumption is much smaller. When the cartesian product is constructed, the input lists are merely copied. Only as the resulting list is iterated are the individual lists created, and these are not retained after iteration.
B
- any common base class shared by all axes (often just
Object
)
lists
- the lists to choose elements from, in the order that the elements chosen from those lists should appear in the resulting lists
IllegalArgumentException
- if the size of the cartesian product would be greater than
Integer.MAX_VALUE
NullPointerException
- if
lists
, any one of the
lists
, or any element of a provided list is null
public static <B> List<List <B>> cartesianProduct(List <? extends B>... lists)
Lists.cartesianProduct(ImmutableList.of( ImmutableList.of(1, 2), ImmutableList.of("A", "B", "C")))
returns a list containing six lists in the following order:
ImmutableList.of(1, "A")
ImmutableList.of(1, "B")
ImmutableList.of(1, "C")
ImmutableList.of(2, "A")
ImmutableList.of(2, "B")
ImmutableList.of(2, "C")
The result is guaranteed to be in the "traditional", lexicographical order for Cartesian products that you would get from nesting for loops:
for (B b0 : lists.get(0)) { for (B b1 : lists.get(1)) { ... ImmutableList<B> tuple = ImmutableList.of(b0, b1, ...); // operate on tuple } }
Note that if any input list is empty, the Cartesian product will also be empty. If no lists at all are provided (an empty list), the resulting Cartesian product has one element, an empty list (counter-intuitive, but mathematically consistent).
Performance notes: while the cartesian product of lists of size m, n, p
is a list of size m x n x p
, its actual memory consumption is much smaller. When the cartesian product is constructed, the input lists are merely copied. Only as the resulting list is iterated are the individual lists created, and these are not retained after iteration.
B
- any common base class shared by all axes (often just
Object
)
lists
- the lists to choose elements from, in the order that the elements chosen from those lists should appear in the resulting lists
IllegalArgumentException
- if the size of the cartesian product would be greater than
Integer.MAX_VALUE
NullPointerException
- if
lists
, any one of the
lists
, or any element of a provided list is null
public static <F,T> List <T> transform(List <F> fromList, Function <? super F ,? extends T> function)
function
to each element of
fromList
. The returned list is a transformed view of
fromList
; changes to
fromList
will be reflected in the returned list and vice versa.
Since functions are not reversible, the transform is one-way and new items cannot be stored in the returned list. The add
, addAll
and set
methods are unsupported in the returned list.
The function is applied lazily, invoked when needed. This is necessary for the returned list to be a view, but it means that the function will be applied many times for bulk operations like List
and List
. For this to perform well, function
should be fast. To avoid lazy evaluation when the returned list doesn't need to be a view, copy the returned list into a new list of your choosing.
If fromList
implements RandomAccess
, so will the returned list. The returned list is threadsafe if the supplied list and function are.
If only a Collection
or Iterable
input is available, use Collections2
or Iterables
.
Note: serializing the returned list is implemented by serializing fromList
, its contents, and function
-- not by serializing the transformed values. This can lead to surprising behavior, so serializing the returned list is not recommended. Instead, copy the list using ImmutableList
(for example), then serialize the copy. Other methods similar to this do not implement serialization at all for this reason.
public static <T> List<List <T>> partition(List <T> list, int size)
[a, b, c, d, e]
with a partition size of 3 yields
[[a, b, c], [d, e]]
-- an outer list containing two inner lists of three and two elements, all in the original order.
The outer list is unmodifiable, but reflects the latest state of the source list. The inner lists are sublist views of the original list, produced on demand using List
, and are subject to all the usual caveats about modification as explained in that API.
list
- the list to return consecutive sublists of
size
- the desired size of each sublist (the last may be smaller)
IllegalArgumentException
- if
partitionSize
is nonpositive
@Beta public static ImmutableList<Character > charactersOf(String string)
Character
values.
@Beta public static List<Character > charactersOf(CharSequence sequence)
CharSequence
as a
List<Character>
, viewing
sequence
as a sequence of Unicode code units. The view does not support any modification operations, but reflects any changes to the underlying character sequence.
sequence
- the character sequence to view as a
List
of characters
List<Character>
view of the character sequence
public static <T> List<T> reverse(List <T> list)
Lists.reverse(Arrays.asList(1, 2, 3))
returns a list containing
3, 2, 1
. The returned list is backed by this list, so changes in the returned list are reflected in this list, and vice-versa. The returned list supports all of the optional list operations supported by this list.
The returned list is random-access if the specified list is random access.