HashMap API Reference
Java HashMap — hash-table-based implementation of the Map interface.
HashMap<K,V>
Hash-table-based implementation of the Map interface. Permits null keys and values.
V put(K key, V value)Associate value with key. Returns the previous value (or null).
Returns: V
V get(Object key)Return the value to which key is mapped, or null if not present.
Returns: V
V remove(Object key)Remove the mapping for key. Returns the previous value (or null).
Returns: V
boolean containsKey(Object key)Return true if the map contains a mapping for the specified key.
Returns: boolean
boolean containsValue(Object value)Return true if the map maps one or more keys to the specified value.
Returns: boolean
Set<K> keySet()Return a Set view of the keys contained in the map.
Returns: Set<K>
Collection<V> values()Return a Collection view of the values contained in the map.
Returns: Collection<V>
Set<Map.Entry<K,V>> entrySet()Return a Set view of the mappings contained in the map.
Returns: Set<Map.Entry<K,V>>
int size()Return the number of key-value mappings in the map.
Returns: int
boolean isEmpty()Return true if the map contains no key-value mappings.
Returns: boolean