Here is the answer.
The java.util.Map interface represents a mapping between a key and a value. The Map interface is not a subtype of the Collection interface. Therefore it behaves a bit different from the rest of the collection types. the interface starts of it?s own interface hierarchy, for maintaining key-value associations.
The interface describes a mapping from keys to values, without duplicate keys, by definition. The Map interface provides three collection views, which allow a map's contents to be viewed as a set of keys, collection of values, or set of key-value mappings. The order of a map is defined as the order in which the iterators on the map's collection views return their elements.
The Map interface maps unique keys to values. A key is an object that you use to retrieve a value at a later date.
Given a key and a value, you can store the value in a Map object. After the value is stored, you can retrieve it by using its key. Several methods throw a NoSuchElementException when no items exist in the invoking map. A ClassCastException is thrown when an object is incompatible with the elements in a map. A ClassCastException is thrown when an object is incompatible with the elements in a map. A NullPointerException is thrown if an attempt is made to use a null object and null is not allowed in the map. An UnsupportedOperationException is thrown when an attempt is made to change an unmodifiable map
If you are facing any programming issue, such as compilation errors or not able to find the code you are looking for.
Ask your questions, our development team will try to give answers to your questions.