Chapter 30.2, Problem 30.2.4CP

Explanation of Solution

Expression of “map” type for given scenario:

map.entrySet().stream().mapToDouble(e->e.getValue()).sum()

Explanation:

The “entrySet()” was retrieved all elements in map and add all the double values using aggregate method “sum()”. It fetch the double values using the method “mapToDouble()”.

Program:

//Import necessary package

import java.util.stream.Stream;

import java.util...