ラムダ式で本領を発揮する関数型インターフェースとStream APIの基礎知識：Java 8はラムダ式でここまで変わる（3）（3/3 ページ）

int maxSalesAmount = salesDataList.parallelStream() ←streamをparallelStreamに変更
        .filter(salesData -> salesData.getLocation().equals("東京"))
        .mapToInt(salesData -> salesData.getSalesAmount())
        .max()
        .getAsInt();

public static void main(String[] args) {
    // 2014年1月末日を取得
    Calendar calendar = Calendar.getInstance();
    calendar.clear();
    calendar.set(2014, 1, 31);
    Date endDateOfJanuary = calendar.getTime();
    // テストデータの生成
    List<SalesData> salesDataList = SalesData.createSalesDateList();
    // 5回実行
    for (int i = 1; i <= 5; i++) {
        System.out.println(i + "回目 ------------------------------");
        // forループの場合
        int maxSalesAmount = -1;
        long start = System.currentTimeMillis();
        for (SalesData salesData : salesDataList) {
            if (salesData.getLocation().equals("東京")) {
                if (salesData.getDate().compareTo(endDateOfJanuary) <= 0) {
                    if (maxSalesAmount < 0) {
                        maxSalesAmount = salesData.getSalesAmount();
                    } else if (maxSalesAmount < salesData.getSalesAmount()) {
                        maxSalesAmount = salesData.getSalesAmount();
                    }
                }
            }
        }
        long end = System.currentTimeMillis();
        System.out.println("forループ： time=" + (end - start) + "ms");
        // streamメソッドの場合
        maxSalesAmount = -1;
        start = System.currentTimeMillis();
        maxSalesAmount = salesDataList.stream()
                .filter(salesData -> salesData.getLocation().equals("東京"))
                .filter(salesData -> salesData.getDate().compareTo(endDateOfJanuary) <= 0)
                .mapToInt(salesData -> salesData.getSalesAmount())
                .max()
                .getAsInt();
        end = System.currentTimeMillis();
        System.out.println("stream： time=" + (end - start) + "ms");
        // parallelStreamメソッドの場合
        maxSalesAmount = -1;
        start = System.currentTimeMillis();
        maxSalesAmount = salesDataList.parallelStream()
                .filter(salesData -> salesData.getLocation().equals("東京"))
                .filter(salesData -> salesData.getDate().compareTo(endDateOfJanuary) <= 0)
                .mapToInt(salesData -> salesData.getSalesAmount())
                .max()
                .getAsInt();
        end = System.currentTimeMillis();
        System.out.println("parallelStream： time=" + (end - start) + "ms");
    }
}

List<String> list = Arrays.asList(
        "list1", "list2", "list3", "list4", "list5"
);
list.stream().forEach(e -> System.out.println("stream: " + e));
list.parallelStream().forEach(e -> System.out.println("parallelStream: " + e));