A Map (also known as an associative array, dictionary, table, and
hash) is an unordered collection of object references. The elements in a
Map collection are accessed by a key value. The keys used in a Map can
be of any class. When we insert into a Map collection, two values are
required: the key and the value.
Following are some examples of maps −
Following are some examples of maps −
- [‘TopicName’ : ‘Lists’, ‘TopicName’ : ‘Maps’] – Collections of key value pairs which has TopicName as the key and their respective values.
- [ : ] – An Empty map.
| S.No. | Methods & Description |
|---|---|
| 1 | containsKey() Does this Map contain this key? |
| 2 | get() Look up the key in this Map and return the corresponding value. If there is no entry in this Map for the key, then return null. |
| 3 | keySet() Obtain a Set of the keys in this Map. |
| 4 | put() Associates the specified value with the specified key in this Map. If this Map previously contained a mapping for this key, the old value is replaced by the specified value. |
| 5 | size() Returns the number of key-value mappings in this Map. |
| 6 | values() Returns a collection view of the values contained in this Map. |
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