package com.programcreek.java8.stream; import java.io.IOException; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.ArrayList; import java.util.List; import java.util.stream.Stream; public class Java8FlatMap { public static void main(String[] args) { ArrayList orders = new ArrayList(); Stream itemStream = orders.stream().flatMap(order -> order.getItems().stream()); } public static Stream convertToCharStream(String s){ ArrayList list = new ArrayList(); for(char c: s.toCharArray()){ list.add(c); } return list.stream(); } public static void test() throws IOException{ Path path = Paths.get(null); Stream lines = Files.lines(path, StandardCharsets.UTF_8); Stream words = lines.flatMap(line -> Stream.of(line.split(" +"))); } } class Order{ String orderId; ArrayList items = new ArrayList(); public Order(String orderId, ArrayList orderItems) { super(); this.orderId = orderId; this.items = orderItems; } public String getOrderId() { return orderId; } public void setOrderId(String orderId) { this.orderId = orderId; } public ArrayList getItems() { return items; } public void setItems(ArrayList orderItems) { this.items = orderItems; } } class Item{ String itemId; String itemName; public Item(String itemId, String itemName) { super(); this.itemId = itemId; this.itemName = itemName; } public String getItemId() { return itemId; } public void setItemId(String itemId) { this.itemId = itemId; } public String getItemName() { return itemName; } public void setItemName(String itemName) { this.itemName = itemName; } }