This class consists exclusively of static methods that operate on or return collections. It contains polymorphic algorithms that operate on collections, "wrappers", which return a new collection backed by a specified collection, and a few other odds and ends.
<p>The methods of this class all throw a NullPointerException if the collections or class objects provided to them are null.
<p>The documentation for the polymorphic algorithms contained in this class generally includes a brief description of the implementation. Such descriptions should be regarded as implementation notes, rather than parts of the specification. Implementors should feel free to substitute other algorithms, so long as the specification itself is adhered to. (For example, the algorithm used by sort does not have to be a mergesort, but it does have to be stable.)
<p>The "destructive" algorithms contained in this [Class], that is, the algorithms that modify the collection on which they operate, are specified to throw UnsupportedOperationException if the collection does not support the appropriate mutation primitive(s), such as the set method. These algorithms may, but are not required to, throw this exception if an invocation would have no effect on the collection. For example, invoking the sort method on an unmodifiable list that is already sorted may or may not throw UnsupportedOperationException.
<p>This class is a member of the
Java Collections Framework.
@author Josh Bloch @author Neal Gafter
03 Members
method
binarySearch
overload 2
#
binarySearch``1(``0(), ``0)
Searches the specified list for the specified object using the binary search algorithm. The list must be sorted into ascending order according to the Comparable natural ordering of its elements (as by the #sort(List) method) prior to making this call. If it is not sorted, the results are undefined. If the list contains multiple elements equal to the specified object, there is no guarantee which one will be found.
<p>This method runs in log(n) time for a "random access" list (which provides near-constant-time positional access). If the specified list does not implement the RandomAccess interface and is large, this method will do an iterator-based binary search that performs O(n) link traversals and O(log n) element comparisons.
Type Parameters
| Name | Description |
|---|
T | the class of the objects in the list |
Parameters
| Name | Type | Description |
|---|
list | ``0() | the list to be searched. |
key | ``0 | the key to be searched for. |
Returns
the index of the search key, if it is contained in the list; otherwise, <tt>(-(<i>insertion point</i>) - 1)</tt>. The <i>insertion point</i> is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or <tt>list.size()</tt> if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
binarySearch``1(``0(), ``0, IComparer(Of ``0))
Searches the specified list for the specified object using the binary search algorithm. The list must be sorted into ascending order according to the specified comparator (as by the #sort(List, Comparator) sort(List, Comparator) method), prior to making this call. If it is not sorted, the results are undefined. If the list contains multiple elements equal to the specified object, there is no guarantee which one will be found.
<p>This method runs in log(n) time for a "random access" list (which provides near-constant-time positional access). If the specified list does not implement the RandomAccess interface and is large, this method will do an iterator-based binary search that performs O(n) link traversals and O(log n) element comparisons.
Type Parameters
| Name | Description |
|---|
T | the class of the objects in the list |
Parameters
| Name | Type | Description |
|---|
list | ``0() | the list to be searched. |
key | ``0 | the key to be searched for. |
c | IComparer(Of ``0) | the comparator by which the list is ordered. A null value indicates that the elements' Comparable natural ordering should be used. |
Returns
the index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size() if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
get``1(IEnumerator(Of ``0), Int32)
Gets the ith element from the given list by repositioning the specified list listIterator.
retainAll``1(IList(Of ``0), IEnumerable(Of ``0))
模拟 Java Collection 中的 retainAll 方法。 仅保留当前集合中包含在指定集合中的元素（即求交集）。 如果集合发生了更改，则返回 True。
Type Parameters
Parameters
| Name | Type | Description |
|---|
source | IList(Of ``0) | 原集合（会被修改） |
itemsToKeep | IEnumerable(Of ``0) | 要保留的元素集合 |
Returns
如果原集合被修改了返回 True，否则返回 False
put(IDictionary(Of K, V), K, V)
method
binarySearch
overload 2
#
binarySearch(T(), T)
binarySearch(T(), T, IComparer(Of T))
retainAll(IList(Of T), IEnumerable(Of T))
shuffle(IList(Of T), Random)
nuget