将值从一个 hashmap 复制到另一个

Question

I have two hashmaps

Map<String, Employee> employees
Map<String, Address> address

and Employee and Address classes look as follows:

class Employee {
 String name,
 String city
}

class Address {
 String city
}

How can I copy city value from "address" hashmap to a city in Employee object of 'employees' hashmap if keys between these two hashmaps (employees and address) matches?

I want to copy with functional java 8 declaratively without for loop.

Answer 1

You are actually trying to manipulate employees map and if you just want to use lambdas for it, it can be done something like this assuming that the keys in both employees and address match:

address.entrySet().forEach(entry -> employees.get(entry.getKey()).setCity(entry.getValue().getCity()));

This can also be rewritten as

address.forEach((key, val) -> employees.get(key).setCity(val.getCity()));

without making use of entrySet()