Cache the entry set, key set, and values collection for unmodifiable maps to reduce object creation on repeated calls.
Patch by: amitmanjhi
Review by: me
git-svn-id: https://google-web-toolkit.googlecode.com/svn/releases/1.6@3916 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/super/com/google/gwt/emul/java/util/Collections.java b/user/super/com/google/gwt/emul/java/util/Collections.java
index 50963d9..b4fd16b 100644
--- a/user/super/com/google/gwt/emul/java/util/Collections.java
+++ b/user/super/com/google/gwt/emul/java/util/Collections.java
@@ -227,7 +227,10 @@
}
}
+ private transient UnmodifiableSet<Map.Entry<K, V>> entrySet;
+ private transient UnmodifiableSet<K> keySet;
private final Map<? extends K, ? extends V> map;
+ private transient UnmodifiableCollection<V> values;
public UnmodifiableMap(Map<? extends K, ? extends V> map) {
this.map = map;
@@ -246,7 +249,10 @@
}
public Set<Map.Entry<K, V>> entrySet() {
- return new UnmodifiableEntrySet<K, V>(map.entrySet());
+ if (entrySet == null) {
+ entrySet = new UnmodifiableEntrySet<K, V>(map.entrySet());
+ }
+ return entrySet;
}
public boolean equals(Object o) {
@@ -266,7 +272,10 @@
}
public Set<K> keySet() {
- return unmodifiableSet(map.keySet());
+ if (keySet == null) {
+ keySet = new UnmodifiableSet<K>(map.keySet());
+ }
+ return keySet;
}
public V put(K key, V value) {
@@ -290,7 +299,10 @@
}
public Collection<V> values() {
- return unmodifiableCollection(map.values());
+ if (values == null) {
+ values = new UnmodifiableCollection<V>(map.values());
+ }
+ return values;
}
}
