Java Map List To Map

The map has two values (a key and value), while a list only has one value (an element). * the list and add the elements to the hashmap */ //map object map<integer, employee> mapemployees = new hashmap<integer, employee>(); Then further i have added few entries into the list.

Hashmap and linkedhashmap allow null keys and values, but treemap doesn't allow any. Using lambda expression, we can convert list to map in a single line. Beginning from the main class, i have declared a list of object js.

Then we will use the reduce function to get the current map and the map that has been constructed till now, or the accumulator map.

For the first case, it will just be the first and the second map in the list. Maps can be used typically when we need to modify a collection based on a key value. The hierarchy of java map is given below: For example, let's say we want to map a list of user entities to a userdto list.