package com.javatechie;
import java.util.List;
import java.util.stream.Collectors;
public class MapVsFlatMap {
public static void main(String[] args) {
List customers = EkartDataBase.getAll();
//List convert List -> Data Transformation
//mapping : customer -> customer.getEmail()
//customer -> customer.getEmail() one to one mapping
List emails = customers.stream()
.map(customer -> customer.getEmail())
.collect(Collectors.toList());
System.out.println(emails);
//customer -> customer.getPhoneNumbers() ->> one to many mapping
//customer -> customer.getPhoneNumbers() ->> one to many mapping
List> phoneNumbers = customers.
stream().map(customer -> customer.getPhoneNumbers())
.collect(Collectors.toList());
System.out.println(phoneNumbers);
//List convert List -> Data Transformation
//mapping : customer -> phone Numbers
//customer -> customer.getPhoneNumbers() ->> one to many mapping
List phones = customers.stream()
.flatMap(customer -> customer.getPhoneNumbers().stream())
.collect(Collectors.toList());
System.out.println(phones);
}
}