LruCache

Kotlin |Java

open class LruCache<K : Any!, V : Any!>

kotlin.Any
↳	android.util.LruCache

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&lt;String, Bitmap&gt; bitmapCache = new LruCache&lt;String, Bitmap&gt;(cacheSize) {
        protected int sizeOf(String key, Bitmap value) {
            return value.getByteCount();
        }
    }</code>

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);
      }
    }</code>

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.

Summary

Public constructors
`LruCache(maxSize: Int)`

Public methods
Int	`createCount()` Returns the number of times `create(java.lang.Object)` returned a value.
Unit	`evictAll()` Clear the cache, calling `entryRemoved` on each removed entry.
Int	`evictionCount()` Returns the number of values that have been evicted.
V	`get(key: K)` Returns the value for `key` if it exists in the cache or can be created by `create`.
Int	`hitCount()` Returns the number of times `get` returned a value that was already present in the cache.
Int	`maxSize()` For caches that do not override `sizeOf`, this returns the maximum number of entries in the cache.
Int	`missCount()` Returns the number of times `get` returned null or required a new value to be created.
V	`put(key: K, value: V)` Caches `value` for `key`.
Int	`putCount()` Returns the number of times `put` was called.
V	`remove(key: K)` Removes the entry for `key` if it exists.
open Unit	`resize(maxSize: Int)` Sets the size of the cache.
Int	`size()` For caches that do not override `sizeOf`, this returns the number of entries in the cache.
MutableMap<K, V>!	`snapshot()` Returns a copy of the current contents of the cache, ordered from least recently accessed to most recently accessed.
String	`toString()`
open Unit	`trimToSize(maxSize: Int)` Remove the eldest entries until the total of remaining entries is at or below the requested size.

Protected methods
open V	`create(key: K)` Called after a cache miss to compute a value for the corresponding key.
open Unit	`entryRemoved(evicted: Boolean, key: K, oldValue: V, newValue: V)` Called for entries that have been evicted or removed.
open Int	`sizeOf(key: K, value: V)` Returns the size of the entry for `key` and `value` in user-defined units.

Parameters
`evicted`	Boolean: true if the entry is being removed to make space, false if the removal was caused by a `put` or `remove`.
`newValue`	V: the new value for `key`, if it exists. If non-null, this removal was caused by a `put` or a `get`. Otherwise it was caused by an eviction or a `remove`.

LruCache

Summary

Public constructors

LruCache

Public methods

createCount

evictAll

evictionCount

get

hitCount

maxSize

missCount

put

putCount

remove

resize

size

snapshot

toString

trimToSize

Protected methods

create

entryRemoved

sizeOf