LruCache Class

Reference

Definition

Namespace:: Android.Util

Assembly:: Mono.Android.dll

Important

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A cache that holds strong references to a limited number of values.

[Android.Runtime.Register("android/util/LruCache", DoNotGenerateAcw=true)]
[Java.Interop.JavaTypeParameters(new System.String[] { "K", "V" })]
public class LruCache : Java.Lang.Object

[<Android.Runtime.Register("android/util/LruCache", DoNotGenerateAcw=true)>]
[<Java.Interop.JavaTypeParameters(new System.String[] { "K", "V" })>]
type LruCache = class
    inherit Object

Inheritance: Object

Object
LruCache

Attributes: RegisterAttribute JavaTypeParametersAttribute

Remarks

A cache that holds strong references to a limited number of values. Each time a value is accessed, it is moved to the head of a queue. When a value is added to a full cache, the value at the end of that queue is evicted and may become eligible for garbage collection.

If your cached values hold resources that need to be explicitly released, override #entryRemoved.

If a cache miss should be computed on demand for the corresponding keys, override #create. This simplifies the calling code, allowing it to assume a value will always be returned, even when there's a cache miss.

By default, the cache size is measured in the number of entries. Override #sizeOf to size the cache in different units. For example, this cache is limited to 4MiB of bitmaps:

{@code
              int cacheSize = 4 * 1024 * 1024; // 4MiB
              LruCache<String, Bitmap> bitmapCache = new LruCache<String, Bitmap>(cacheSize) {
                  protected int sizeOf(String key, Bitmap value) {
                      return value.getByteCount();
                  }
              }}

This class is thread-safe. Perform multiple cache operations atomically by synchronizing on the cache:

{@code
              synchronized (cache) {
                if (cache.get(key) == null) {
                    cache.put(key, value);
                }
              }}

This class does not allow null to be used as a key or value. A return value of null from #get, #put or #remove is unambiguous: the key was not in the cache.

This class appeared in Android 3.1 (Honeycomb MR1); it's available as part of Android's Support Package for earlier releases.

Java documentation for android.util.LruCache.

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.

Constructors

LruCache(Int32)
LruCache(IntPtr, JniHandleOwnership)	A constructor used when creating managed representations of JNI objects; called by the runtime.

Properties

Class	Returns the runtime class of this `Object`. (Inherited from Object)
Handle	The handle to the underlying Android instance. (Inherited from Object)
JniIdentityHashCode	(Inherited from Object)
JniPeerMembers
PeerReference	(Inherited from Object)
ThresholdClass	This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.
ThresholdType	This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.

Methods

Clone()	Creates and returns a copy of this object. (Inherited from Object)
Create(Object)	Called after a cache miss to compute a value for the corresponding key.
CreateCount()	Returns the number of times `#create(Object)` returned a value.
Dispose()	(Inherited from Object)
Dispose(Boolean)	(Inherited from Object)
EntryRemoved(Boolean, Object, Object, Object)	Called for entries that have been evicted or removed.
Equals(Object)	Indicates whether some other object is "equal to" this one. (Inherited from Object)
EvictAll()	Clear the cache, calling `#entryRemoved` on each removed entry.
EvictionCount()	Returns the number of values that have been evicted.
Get(Object)	Returns the value for `key` if it exists in the cache or can be created by `#create`.
GetHashCode()	Returns a hash code value for the object. (Inherited from Object)
HitCount()	Returns the number of times `#get` returned a value that was already present in the cache.
JavaFinalize()	Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. (Inherited from Object)
MaxSize()	For caches that do not override `#sizeOf`, this returns the maximum number of entries in the cache.
MissCount()	Returns the number of times `#get` returned null or required a new value to be created.
Notify()	Wakes up a single thread that is waiting on this object's monitor. (Inherited from Object)
NotifyAll()	Wakes up all threads that are waiting on this object's monitor. (Inherited from Object)
Put(Object, Object)	Caches `value` for `key`.
PutCount()	Returns the number of times `#put` was called.
Remove(Object)	Removes the entry for `key` if it exists.
Resize(Int32)	Sets the size of the cache.
SetHandle(IntPtr, JniHandleOwnership)	Sets the Handle property. (Inherited from Object)
Size()	For caches that do not override `#sizeOf`, this returns the number of entries in the cache.
SizeOf(Object, Object)	Returns the size of the entry for `key` and `value` in user-defined units.
Snapshot()	Returns a copy of the current contents of the cache, ordered from least recently accessed to most recently accessed.
ToArray<T>()	(Inherited from Object)
ToString()	Returns a string containing a concise, human-readable description of this object.
TrimToSize(Int32)	Remove the eldest entries until the total of remaining entries is at or below the requested size.
UnregisterFromRuntime()	(Inherited from Object)
Wait()	Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>. (Inherited from Object)
Wait(Int64)	Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object)
Wait(Int64, Int32)	Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object)

Explicit Interface Implementations

IJavaPeerable.Disposed()	(Inherited from Object)
IJavaPeerable.DisposeUnlessReferenced()	(Inherited from Object)
IJavaPeerable.Finalized()	(Inherited from Object)
IJavaPeerable.JniManagedPeerState	(Inherited from Object)
IJavaPeerable.SetJniIdentityHashCode(Int32)	(Inherited from Object)
IJavaPeerable.SetJniManagedPeerState(JniManagedPeerStates)	(Inherited from Object)
IJavaPeerable.SetPeerReference(JniObjectReference)	(Inherited from Object)

Extension Methods

JavaCast<TResult>(IJavaObject)	Performs an Android runtime-checked type conversion.
JavaCast<TResult>(IJavaObject)
GetJniTypeName(IJavaPeerable)

Applies to