boolean replace(K key, int hash, V oldValue, V newValue) {
lock();
try {
int c = count;
HashEntry[] tab = table;
int index = hash & (tab.length - 1);
HashEntry<K, V> first = (HashEntry<K, V>) tab[index];
HashEntry<K, V> e = first;
for (; ; ) {
if (e == null) return false;
if (e.hash == hash && key.equals(e.key)) break;
e = e.next;
}
V v = e.value;
if (v == null || !oldValue.equals(v)) return false;
e.value = newValue;
count = c; // write-volatile
return true;
} finally {
unlock();
}
}
public int hashCode() {
return ((key == null) ? 0 : key.hashCode()) ^ ((value == null) ? 0 : value.hashCode());
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry)) return false;
Map.Entry<K, V> e = (Map.Entry<K, V>) o;
V v = ConcurrentHashMap.this.get(e.getKey());
return v != null && v.equals(e.getValue());
}