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RandomAccess
interface RandomAccess
Known Direct Subclasses
ArrayList |
Resizable-array implementation of the List interface.
|
CopyOnWriteArrayList |
A thread-safe variant of java.util.ArrayList in which all mutative operations (add , set , and so on) are implemented by making a fresh copy of the underlying array.
|
Vector |
The Vector class implements a growable array of objects.
|
|
Known Indirect Subclasses
Stack |
The Stack class represents a last-in-first-out (LIFO) stack of objects.
|
|
Marker interface used by List
implementations to indicate that they support fast (generally constant time) random access. The primary purpose of this interface is to allow generic algorithms to alter their behavior to provide good performance when applied to either random or sequential access lists.
The best algorithms for manipulating random access lists (such as ArrayList
) can produce quadratic behavior when applied to sequential access lists (such as LinkedList
). Generic list algorithms are encouraged to check whether the given list is an instanceof
this interface before applying an algorithm that would provide poor performance if it were applied to a sequential access list, and to alter their behavior if necessary to guarantee acceptable performance.
It is recognized that the distinction between random and sequential access is often fuzzy. For example, some List
implementations provide asymptotically linear access times if they get huge, but constant access times in practice. Such a List
implementation should generally implement this interface. As a rule of thumb, a List
implementation should implement this interface if, for typical instances of the class, this loop:
for (int i=0, n=list.size(); i < n; i++)
list.get(i);
runs faster than this loop:
for (Iterator i=list.iterator(); i.hasNext(); )
i.next();
This interface is a member of the Java Collections Framework.
Summary
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2025-02-10 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-02-10 UTC."],[],[],null,["# RandomAccess\n\nAdded in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)\n\nRandomAccess\n============\n\n```\ninterface RandomAccess\n```\n\n|-----------------------------|\n| [java.util.RandomAccess](#) |\n\n|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| Known Direct Subclasses [ArrayList](/reference/kotlin/java/util/ArrayList), [CopyOnWriteArrayList](/reference/kotlin/java/util/concurrent/CopyOnWriteArrayList), [Vector](/reference/kotlin/java/util/Vector) |-------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [ArrayList](/reference/kotlin/java/util/ArrayList) | Resizable-array implementation of the `List` interface. | | [CopyOnWriteArrayList](/reference/kotlin/java/util/concurrent/CopyOnWriteArrayList) | A thread-safe variant of [java.util.ArrayList](/reference/kotlin/java/util/ArrayList) in which all mutative operations (`add`, `set`, and so on) are implemented by making a fresh copy of the underlying array. | | [Vector](/reference/kotlin/java/util/Vector) | The `Vector` class implements a growable array of objects. | |\n\n|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| Known Indirect Subclasses [Stack](/reference/kotlin/java/util/Stack) |--------------------------------------------|---------------------------------------------------------------------------| | [Stack](/reference/kotlin/java/util/Stack) | The `Stack` class represents a last-in-first-out (LIFO) stack of objects. | |\n\nMarker interface used by `List` implementations to indicate that they support fast (generally constant time) random access. The primary purpose of this interface is to allow generic algorithms to alter their behavior to provide good performance when applied to either random or sequential access lists.\n\nThe best algorithms for manipulating random access lists (such as `ArrayList`) can produce quadratic behavior when applied to sequential access lists (such as `LinkedList`). Generic list algorithms are encouraged to check whether the given list is an `instanceof` this interface before applying an algorithm that would provide poor performance if it were applied to a sequential access list, and to alter their behavior if necessary to guarantee acceptable performance.\n\nIt is recognized that the distinction between random and sequential access is often fuzzy. For example, some `List` implementations provide asymptotically linear access times if they get huge, but constant access times in practice. Such a `List` implementation should generally implement this interface. As a rule of thumb, a `List` implementation should implement this interface if, for typical instances of the class, this loop: \n\n```kotlin\nfor (int i=0, n=list.size(); i \u003c n; i++)\n list.get(i);\n \n```\nruns faster than this loop: \n\n```kotlin\nfor (Iterator i=list.iterator(); i.hasNext(); )\n i.next();\n \n```\n\nThis interface is a member of the [Java Collections Framework](https://developer.android.com//reference/java/util/package-summary.html#CollectionsFramework).\n\nSummary\n-------"]]