JavaHashMap Methods
All HashMap Methods
A list of allHashMap methods can be found in the table below.
Some methods use the type of the HashMap's entries as a parameter or return value. The type of the key will be referred to asK and the type of the value will be referred to asV in the table.
| Method | Description | Return Type |
|---|---|---|
| clear() | Remove all entries from the map. | void |
| clone() | Create a copy of the HashMap. | Object |
| compute() | Compute a value for an entry based on its key and the current value (if it has one) | V |
| computeIfAbsent() | Compute a value for an entry based on its key only if an entry using the key does not already exist | V |
| computeIfPresent() | Compute a new value for an entry based on its key and current value but only if an entry with the key already exists | V |
| containsKey() | Indicate if an entry with the specified key exists in the map | boolean |
| containsValue() | Indicate if an entry with the specified value exists in the map | boolean |
| entrySet() | Return a set of all entries in the map | Set< Map.Entry<K,V> > |
| forEach() | Perform an action on every entry in the map | void |
| get() | Return the value of the entry with a specified key | V |
| getOrDefault() | Return the value of the entry with a specified key or a default value if the entry is not found | V |
| isEmpty() | Indicate whether the map is empty | boolean |
| keySet() | Return a set of all keys in the map | Set<K> |
| merge() | Compute a value for an entry based on its key and value or write a specific value if the entry does not yet exist | V |
| put() | Write an entry into the map | V |
| putAll() | Write all of the entries from another map into this one | void |
| putIfAbsent() | Write an entry into the map but only if an entry with the same key does not already exist | V |
| remove() | Remove an entry from the map | V|boolean |
| replace() | Write to an entry in the map only if it exists | V|boolean |
| replaceAll() | Replaces the value of every entry with the result of an operation | void |
| size() | Return the number of entries in the map | int |
| values() | Return a collection containing all of the values in the map | Collection<V> |
