List

类型参数:

E - the type of elements in this list

所有超级接口:

Collection<E>, Iterable<E>

所有已知实现类:

AbstractList, AbstractSequentialList, ArrayList, CopyOnWriteArrayList, LinkedList, Stack, Vector
```
public interface List<E>
extends Collection<E>
```
An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list.
Unlike sets, lists typically allow duplicate elements. More formally, lists typically allow pairs of elements e1 and e2 such that e1.equals(e2), and they typically allow multiple null elements if they allow null elements at all. It is not inconceivable that someone might wish to implement a list that prohibits duplicates, by throwing runtime exceptions when the user attempts to insert them, but we expect this usage to be rare.
The List interface places additional stipulations, beyond those specified in the Collection interface, on the contracts of the iterator, add, remove, equals, and hashCode methods. Declarations for other inherited methods are also included here for convenience.
The List interface provides four methods for positional (indexed) access to list elements. Lists (like Java arrays) are zero based. Note that these operations may execute in time proportional to the index value for some implementations (the LinkedList class, for example). Thus, iterating over the elements in a list is typically preferable to indexing through it if the caller does not know the implementation.
The List interface provides a special iterator, called a ListIterator, that allows element insertion and replacement, and bidirectional access in addition to the normal operations that the Iterator interface provides. A method is provided to obtain a list iterator that starts at a specified position in the list.
The List interface provides two methods to search for a specified object. From a performance standpoint, these methods should be used with caution. In many implementations they will perform costly linear searches.
The List interface provides two methods to efficiently insert and remove multiple elements at an arbitrary point in the list.
Note: While it is permissible for lists to contain themselves as elements, extreme caution is advised: the equals and hashCode methods are no longer well defined on such a list.
Some list implementations have restrictions on the elements that they may contain. For example, some implementations prohibit null elements, and some have restrictions on the types of their elements. Attempting to add an ineligible element throws an unchecked exception, typically NullPointerException or ClassCastException. Attempting to query the presence of an ineligible element may throw an exception, or it may simply return false; some implementations will exhibit the former behavior and some will exhibit the latter. More generally, attempting an operation on an ineligible element whose completion would not result in the insertion of an ineligible element into the list may throw an exception or it may succeed, at the option of the implementation. Such exceptions are marked as "optional" in the specification for this interface.
This interface is a member of the Java Collections Framework.

从以下版本开始:

1.2

另请参阅:

Collection, Set, ArrayList, LinkedList, Vector, Arrays.asList(Object[]), Collections.nCopies(int, Object), Collections.EMPTY_LIST, AbstractList, AbstractSequentialList

方法概要

所有方法实例方法抽象方法默认方法
限定符和类型	方法	说明
`void`	`add(int index, E element)`	Inserts the specified element at the specified position in this list (optional operation).
`boolean`	`add(E e)`	Appends the specified element to the end of this list (optional operation).
`boolean`	`addAll(int index, Collection<? extends E> c)`	Inserts all of the elements in the specified collection into this list at the specified position (optional operation).
`boolean`	`addAll(Collection<? extends E> c)`	Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's iterator (optional operation).
`void`	`clear()`	Removes all of the elements from this list (optional operation).
`boolean`	`contains(Object o)`	Returns `true` if this list contains the specified element.
`boolean`	`containsAll(Collection<?> c)`	Returns `true` if this list contains all of the elements of the specified collection.
`boolean`	`equals(Object o)`	Compares the specified object with this list for equality.
`E`	`get(int index)`	Returns the element at the specified position in this list.
`int`	`hashCode()`	Returns the hash code value for this list.
`int`	`indexOf(Object o)`	Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
`boolean`	`isEmpty()`	Returns `true` if this list contains no elements.
`Iterator<E>`	`iterator()`	Returns an iterator over the elements in this list in proper sequence.
`int`	`lastIndexOf(Object o)`	Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
`ListIterator<E>`	`listIterator()`	Returns a list iterator over the elements in this list (in proper sequence).
`ListIterator<E>`	`listIterator(int index)`	Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.
`E`	`remove(int index)`	Removes the element at the specified position in this list (optional operation).
`boolean`	`remove(Object o)`	Removes the first occurrence of the specified element from this list, if it is present (optional operation).
`boolean`	`removeAll(Collection<?> c)`	Removes from this list all of its elements that are contained in the specified collection (optional operation).
`default void`	`replaceAll(UnaryOperator<E> operator)`	Replaces each element of this list with the result of applying the operator to that element.
`boolean`	`retainAll(Collection<?> c)`	Retains only the elements in this list that are contained in the specified collection (optional operation).
`E`	`set(int index, E element)`	Replaces the element at the specified position in this list with the specified element (optional operation).
`int`	`size()`	Returns the number of elements in this list.
`default void`	`sort(Comparator<? super E> c)`	Sorts this list according to the order induced by the specified `Comparator`.
`default Spliterator<E>`	`spliterator()`	Creates a `Spliterator` over the elements in this list.
`List<E>`	`subList(int fromIndex, int toIndex)`	Returns a view of the portion of this list between the specified `fromIndex`, inclusive, and `toIndex`, exclusive.
`Object[]`	`toArray()`	Returns an array containing all of the elements in this list in proper sequence (from first to last element).
`<T> T[]`	`toArray(T[] a)`	Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.

从接口继承的方法 java.util.Collection
parallelStream, removeIf, stream

从接口继承的方法 java.lang.Iterable
forEach

- 方法详细资料
  - size
```
int size()
```
    Returns the number of elements in this list. If this list contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
    
    指定者:
    
    size 在接口中 Collection<E>
    
    返回:
    
    the number of elements in this list
  - isEmpty
```
boolean isEmpty()
```
    Returns true if this list contains no elements.
    
    指定者:
    
    isEmpty 在接口中 Collection<E>
    
    返回:
    
    true if this list contains no elements
  - contains
```
boolean contains(Object o)
```
    Returns true if this list contains the specified element. More formally, returns true if and only if this list contains at least one element e such that (o==null ? e==null : o.equals(e)).
    
    指定者:
    
    contains 在接口中 Collection<E>
    
    参数:
    
    o - element whose presence in this list is to be tested
    
    返回:
    
    true if this list contains the specified element
    
    抛出:
    
    ClassCastException - if the type of the specified element is incompatible with this list (optional)
    
    NullPointerException - if the specified element is null and this list does not permit null elements (optional)
  - iterator
```
Iterator<E> iterator()
```
    Returns an iterator over the elements in this list in proper sequence.
    
    指定者:
    
    iterator 在接口中 Collection<E>
    
    指定者:
    
    iterator 在接口中 Iterable<E>
    
    返回:
    
    an iterator over the elements in this list in proper sequence
  - toArray
```
Object[] toArray()
```
    Returns an array containing all of the elements in this list in proper sequence (from first to last element).
    The returned array will be "safe" in that no references to it are maintained by this list. (In other words, this method must allocate a new array even if this list is backed by an array). The caller is thus free to modify the returned array.
    This method acts as bridge between array-based and collection-based APIs.
    
    指定者:
    
    toArray 在接口中 Collection<E>
    
    返回:
    
    an array containing all of the elements in this list in proper sequence
    
    另请参阅:
    
    Arrays.asList(Object[])
  - toArray
```
<T> T[] toArray(T[] a)
```
    Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.
    If the list fits in the specified array with room to spare (i.e., the array has more elements than the list), the element in the array immediately following the end of the list is set to null. (This is useful in determining the length of the list only if the caller knows that the list does not contain any null elements.)
    Like the toArray() method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.
    Suppose x is a list known to contain only strings. The following code can be used to dump the list into a newly allocated array of String:
```
     String[] y = x.toArray(new String[0]);
 
```
    Note that toArray(new Object[0]) is identical in function to toArray().
    指定者:
    
    toArray 在接口中 Collection<E>
    
    类型参数:
    
    T - the runtime type of the array to contain the collection
    
    参数:
    
    a - the array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
    
    返回:
    
    an array containing the elements of this list
    
    抛出:
    
    ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this list
    
    NullPointerException - if the specified array is null
  - add
```
boolean add(E e)
```
    Appends the specified element to the end of this list (optional operation).
    Lists that support this operation may place limitations on what elements may be added to this list. In particular, some lists will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. List classes should clearly specify in their documentation any restrictions on what elements may be added.
    
    指定者:
    
    add 在接口中 Collection<E>
    
    参数:
    
    e - element to be appended to this list
    
    返回:
    
    true (as specified by Collection#add)
    
    抛出:
    
    UnsupportedOperationException - if the add operation is not supported by this list
    
    ClassCastException - if the class of the specified element prevents it from being added to this list
    
    NullPointerException - if the specified element is null and this list does not permit null elements
    
    IllegalArgumentException - if some property of this element prevents it from being added to this list
  - remove
```
boolean remove(Object o)
```
    Removes the first occurrence of the specified element from this list, if it is present (optional operation). If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))) (if such an element exists). Returns true if this list contained the specified element (or equivalently, if this list changed as a result of the call).
    
    指定者:
    
    remove 在接口中 Collection<E>
    
    参数:
    
    o - element to be removed from this list, if present
    
    返回:
    
    true if this list contained the specified element
    
    抛出:
    
    ClassCastException - if the type of the specified element is incompatible with this list (optional)
    
    NullPointerException - if the specified element is null and this list does not permit null elements (optional)
    
    UnsupportedOperationException - if the remove operation is not supported by this list
  - containsAll
```
boolean containsAll(Collection<?> c)
```
    Returns true if this list contains all of the elements of the specified collection.
    
    指定者:
    
    containsAll 在接口中 Collection<E>
    
    参数:
    
    c - collection to be checked for containment in this list
    
    返回:
    
    true if this list contains all of the elements of the specified collection
    
    抛出:
    
    ClassCastException - if the types of one or more elements in the specified collection are incompatible with this list (optional)
    
    NullPointerException - if the specified collection contains one or more null elements and this list does not permit null elements (optional), or if the specified collection is null
    
    另请参阅:
    
    contains(Object)
  - addAll
```
boolean addAll(Collection<? extends E> c)
```
    Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's iterator (optional operation). The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)
    
    指定者:
    
    addAll 在接口中 Collection<E>
    
    参数:
    
    c - collection containing elements to be added to this list
    
    返回:
    
    true if this list changed as a result of the call
    
    抛出:
    
    UnsupportedOperationException - if the addAll operation is not supported by this list
    
    ClassCastException - if the class of an element of the specified collection prevents it from being added to this list
    
    NullPointerException - if the specified collection contains one or more null elements and this list does not permit null elements, or if the specified collection is null
    
    IllegalArgumentException - if some property of an element of the specified collection prevents it from being added to this list
    
    另请参阅:
    
    add(Object)
  - addAll
```
boolean addAll(int index,
               Collection<? extends E> c)
```
    Inserts all of the elements in the specified collection into this list at the specified position (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in this list in the order that they are returned by the specified collection's iterator. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)
    
    参数:
    
    index - index at which to insert the first element from the specified collection
    
    c - collection containing elements to be added to this list
    
    返回:
    
    true if this list changed as a result of the call
    
    抛出:
    
    UnsupportedOperationException - if the addAll operation is not supported by this list
    
    ClassCastException - if the class of an element of the specified collection prevents it from being added to this list
    
    NullPointerException - if the specified collection contains one or more null elements and this list does not permit null elements, or if the specified collection is null
    
    IllegalArgumentException - if some property of an element of the specified collection prevents it from being added to this list
    
    IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())
  - removeAll
```
boolean removeAll(Collection<?> c)
```
    Removes from this list all of its elements that are contained in the specified collection (optional operation).
    
    指定者:
    
    removeAll 在接口中 Collection<E>
    
    参数:
    
    c - collection containing elements to be removed from this list
    
    返回:
    
    true if this list changed as a result of the call
    
    抛出:
    
    UnsupportedOperationException - if the removeAll operation is not supported by this list
    
    ClassCastException - if the class of an element of this list is incompatible with the specified collection (optional)
    
    NullPointerException - if this list contains a null element and the specified collection does not permit null elements (optional), or if the specified collection is null
    
    另请参阅:
    
    remove(Object), contains(Object)
  - retainAll
```
boolean retainAll(Collection<?> c)
```
    Retains only the elements in this list that are contained in the specified collection (optional operation). In other words, removes from this list all of its elements that are not contained in the specified collection.
    
    指定者:
    
    retainAll 在接口中 Collection<E>
    
    参数:
    
    c - collection containing elements to be retained in this list
    
    返回:
    
    true if this list changed as a result of the call
    
    抛出:
    
    UnsupportedOperationException - if the retainAll operation is not supported by this list
    
    ClassCastException - if the class of an element of this list is incompatible with the specified collection (optional)
    
    NullPointerException - if this list contains a null element and the specified collection does not permit null elements (optional), or if the specified collection is null
    
    另请参阅:
    
    remove(Object), contains(Object)
  - replaceAll
```
default void replaceAll(UnaryOperator<E> operator)
```
    Replaces each element of this list with the result of applying the operator to that element. Errors or runtime exceptions thrown by the operator are relayed to the caller.
    
    参数:
    
    operator - the operator to apply to each element
    
    抛出:
    
    UnsupportedOperationException - if this list is unmodifiable. Implementations may throw this exception if an element cannot be replaced or if, in general, modification is not supported
    
    NullPointerException - if the specified operator is null or if the operator result is a null value and this list does not permit null elements (optional)
    
    从以下版本开始:
    
    1.8
  - sort
```
default void sort(Comparator<? super E> c)
```
    Sorts this list according to the order induced by the specified Comparator.
    All elements in this list must be mutually comparable using the specified comparator (that is, c.compare(e1, e2) must not throw a ClassCastException for any elements e1 and e2 in the list).
    If the specified comparator is null then all elements in this list must implement the Comparable interface and the elements' Comparable should be used.
    This list must be modifiable, but need not be resizable.
    
    参数:
    
    c - the Comparator used to compare list elements. A null value indicates that the elements' Comparable should be used
    
    抛出:
    
    ClassCastException - if the list contains elements that are not mutually comparable using the specified comparator
    
    UnsupportedOperationException - if the list's list-iterator does not support the set operation
    
    IllegalArgumentException - (optional) if the comparator is found to violate the Comparator contract
    
    从以下版本开始:
    
    1.8
  - clear
```
void clear()
```
    Removes all of the elements from this list (optional operation). The list will be empty after this call returns.
    
    指定者:
    
    clear 在接口中 Collection<E>
    
    抛出:
    
    UnsupportedOperationException - if the clear operation is not supported by this list
  - equals
```
boolean equals(Object o)
```
    Compares the specified object with this list for equality. Returns true if and only if the specified object is also a list, both lists have the same size, and all corresponding pairs of elements in the two lists are equal. (Two elements e1 and e2 are equal if (e1==null ? e2==null : e1.equals(e2)).) In other words, two lists are defined to be equal if they contain the same elements in the same order. This definition ensures that the equals method works properly across different implementations of the List interface.
    
    指定者:
    
    equals 在接口中 Collection<E>
    
    覆盖:
    
    equals 在类中 Object
    
    参数:
    
    o - the object to be compared for equality with this list
    
    返回:
    
    true if the specified object is equal to this list
    
    另请参阅:
    
    Object.hashCode(), HashMap
  - hashCode
```
int hashCode()
```
    Returns the hash code value for this list. The hash code of a list is defined to be the result of the following calculation:
```
     int hashCode = 1;
     for (E e : list)
         hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
 
```
    This ensures that list1.equals(list2) implies that list1.hashCode()==list2.hashCode() for any two lists, list1 and list2, as required by the general contract of Object#hashCode.
    指定者:
    
    hashCode 在接口中 Collection<E>
    
    覆盖:
    
    hashCode 在类中 Object
    
    返回:
    
    the hash code value for this list
    
    另请参阅:
    
    Object.equals(Object), equals(Object)
  - get
```
E get(int index)
```
    Returns the element at the specified position in this list.
    
    参数:
    
    index - index of the element to return
    
    返回:
    
    the element at the specified position in this list
    
    抛出:
    
    IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())
  - set
```
E set(int index,
      E element)
```
    Replaces the element at the specified position in this list with the specified element (optional operation).
    
    参数:
    
    index - index of the element to replace
    
    element - element to be stored at the specified position
    
    返回:
    
    the element previously at the specified position
    
    抛出:
    
    UnsupportedOperationException - if the set operation is not supported by this list
    
    ClassCastException - if the class of the specified element prevents it from being added to this list
    
    NullPointerException - if the specified element is null and this list does not permit null elements
    
    IllegalArgumentException - if some property of the specified element prevents it from being added to this list
    
    IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())
  - add
```
void add(int index,
         E element)
```
    Inserts the specified element at the specified position in this list (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).
    
    参数:
    
    index - index at which the specified element is to be inserted
    
    element - element to be inserted
    
    抛出:
    
    UnsupportedOperationException - if the add operation is not supported by this list
    
    ClassCastException - if the class of the specified element prevents it from being added to this list
    
    NullPointerException - if the specified element is null and this list does not permit null elements
    
    IllegalArgumentException - if some property of the specified element prevents it from being added to this list
    
    IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())
  - remove
```
E remove(int index)
```
    Removes the element at the specified position in this list (optional operation). Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.
    
    参数:
    
    index - the index of the element to be removed
    
    返回:
    
    the element previously at the specified position
    
    抛出:
    
    UnsupportedOperationException - if the remove operation is not supported by this list
    
    IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())
  - indexOf
```
int indexOf(Object o)
```
    Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
    
    参数:
    
    o - element to search for
    
    返回:
    
    the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element
    
    抛出:
    
    ClassCastException - if the type of the specified element is incompatible with this list (optional)
    
    NullPointerException - if the specified element is null and this list does not permit null elements (optional)
  - lastIndexOf
```
int lastIndexOf(Object o)
```
    Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the highest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
    
    参数:
    
    o - element to search for
    
    返回:
    
    the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element
    
    抛出:
    
    ClassCastException - if the type of the specified element is incompatible with this list (optional)
    
    NullPointerException - if the specified element is null and this list does not permit null elements (optional)
  - listIterator
```
ListIterator<E> listIterator()
```
    Returns a list iterator over the elements in this list (in proper sequence).
    
    返回:
    
    a list iterator over the elements in this list (in proper sequence)
  - listIterator
```
ListIterator<E> listIterator(int index)
```
    Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. The specified index indicates the first element that would be returned by an initial call to ListIterator#next. An initial call to ListIterator#previous would return the element with the specified index minus one.
    
    参数:
    
    index - index of the first element to be returned from the list iterator (by a call to ListIterator#next)
    
    返回:
    
    a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list
    
    抛出:
    
    IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())
  - subList
```
List<E> subList(int fromIndex,
                int toIndex)
```
    Returns a view of the portion of this list between the specified fromIndex, inclusive, and toIndex, exclusive. (If fromIndex and toIndex are equal, the returned list is empty.) The returned list is backed by this list, so non-structural 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.
    This method eliminates the need for explicit range operations (of the sort that commonly exist for arrays). Any operation that expects a list can be used as a range operation by passing a subList view instead of a whole list. For example, the following idiom removes a range of elements from a list:
```
      list.subList(from, to).clear();
 
```
    Similar idioms may be constructed for indexOf and lastIndexOf, and all of the algorithms in the Collections class can be applied to a subList.
    The semantics of the list returned by this method become undefined if the backing list (i.e., this list) is structurally modified in any way other than via the returned list. (Structural modifications are those that change the size of this list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.)
    参数:
    
    fromIndex - low endpoint (inclusive) of the subList
    
    toIndex - high endpoint (exclusive) of the subList
    
    返回:
    
    a view of the specified range within this list
    
    抛出:
    
    IndexOutOfBoundsException - for an illegal endpoint index value (fromIndex < 0 || toIndex > size || fromIndex > toIndex)
  - spliterator
```
default Spliterator<E> spliterator()
```
    Creates a Spliterator over the elements in this list.
    The Spliterator reports Spliterator#SIZED and Spliterator#ORDERED. Implementations should document the reporting of additional characteristic values.
    
    指定者:
    
    spliterator 在接口中 Collection<E>
    
    指定者:
    
    spliterator 在接口中 Iterable<E>
    
    返回:
    
    a Spliterator over the elements in this list
    
    从以下版本开始:
    
    1.8

接口 List<E>

方法概要

从接口继承的方法 java.util.Collection

从接口继承的方法 java.lang.Iterable

方法详细资料

size

isEmpty

contains

iterator

toArray

toArray

add

remove

containsAll

addAll

addAll

removeAll

retainAll

replaceAll

sort

clear

equals

hashCode

get

set

add

remove

indexOf

lastIndexOf

listIterator

listIterator

subList

spliterator