iframe-proxy | Sunbelt Computer Software

34 lines (28 loc) · 1.35 KB

package com.javatechie;

import java.util.List;

import java.util.stream.Collectors;

public class MapVsFlatMap {

public static void main(String[] args) {

List<Customer> customers = EkartDataBase.getAll();

//List<Customer> convert List<String> -> Data Transformation

//mapping : customer -> customer.getEmail()

//customer -> customer.getEmail() one to one mapping

List<String> emails = customers.stream()

.map(customer -> customer.getEmail())

.collect(Collectors.toList());

System.out.println(emails);

//customer -> customer.getPhoneNumbers() ->> one to many mapping

List<List<String>> phoneNumbers = customers.

stream().map(customer -> customer.getPhoneNumbers())

.collect(Collectors.toList());

System.out.println(phoneNumbers);

//List<Customer> convert List<String> -> Data Transformation

//mapping : customer -> phone Numbers

//customer -> customer.getPhoneNumbers() ->> one to many mapping

List<String> phones = customers.stream()

.flatMap(customer -> customer.getPhoneNumbers().stream())

.collect(Collectors.toList());

System.out.println(phones);

}

Sunbelt Computer Software