diff options
Diffstat (limited to 'core/java/android/util')
-rw-r--r-- | core/java/android/util/LruCache.java | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/core/java/android/util/LruCache.java b/core/java/android/util/LruCache.java index 2122050..5578e6a 100644 --- a/core/java/android/util/LruCache.java +++ b/core/java/android/util/LruCache.java @@ -51,6 +51,10 @@ import java.util.Map; * cache.put(key, value); * } * }}</pre> + * + * <p>This class does not allow null to be used as a key or value. A return + * value of null from {@link #get}, {@link #put} or {@link #remove} is + * unambiguous: the key was not in the cache. */ public class LruCache<K, V> { private final LinkedHashMap<K, V> map; @@ -86,7 +90,7 @@ public class LruCache<K, V> { */ public synchronized final V get(K key) { if (key == null) { - throw new NullPointerException(); + throw new NullPointerException("key == null"); } V result = map.get(key); @@ -118,7 +122,7 @@ public class LruCache<K, V> { */ public synchronized final V put(K key, V value) { if (key == null || value == null) { - throw new NullPointerException(); + throw new NullPointerException("key == null || value == null"); } putCount++; @@ -133,7 +137,7 @@ public class LruCache<K, V> { private void trimToSize(int maxSize) { while (size > maxSize) { - Map.Entry<K, V> toEvict = map.eldest(); + Map.Entry<K, V> toEvict = map.eldest(); // equal to map.entrySet().iterator().next(); if (toEvict == null) { break; // map is empty; if size is not 0 then throw an error below } @@ -155,6 +159,24 @@ public class LruCache<K, V> { } /** + * Removes the entry for {@code key} if it exists. + * + * @return the previous value mapped by {@code key}. Although that entry is + * no longer cached, it has not been passed to {@link #entryEvicted}. + */ + public synchronized final V remove(K key) { + if (key == null) { + throw new NullPointerException("key == null"); + } + + V previous = map.remove(key); + if (previous != null) { + size -= safeSizeOf(key, previous); + } + return previous; + } + + /** * Called for entries that have reached the tail of the least recently used * queue and are be removed. The default implementation does nothing. */ |