1. Associate the specified value with the specified key in a HashMap.
2. Count the number of key-value (size) mappings in a map.
3. Copy all of the mappings from the specified map to another map.
4. Remove all of the mappings from a map.
5. Check whether a map contains key-value mappings (empty) or not.
6. Get a shallow copy of a HashMap instance.
7. Test if a map contains a mapping for the specified key.
8. Test if a map contains a mapping for the specified value.
9. To create a set view of the mappings contained in a map.
10. To get the value of a specified key in a map.
11. To get a set view of the keys contained in this map.
12. To get a collection view of the values contained in this map.