收集器Collectors

最新推荐文章于 2025-08-23 19:36:46 发布

转载最新推荐文章于 2025-08-23 19:36:46 发布 · 92 阅读

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原文链接：http://www.cnblogs.com/i-hard-working/p/9588092.html

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#java

package com.ant.jdk8.chap06;

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class GroupingTransaction {
    public static void main(String[] args) {
        List<Transaction> transactions = Arrays.asList(
                new Transaction(Currency.EUR, 1500.0),
                new Transaction(Currency.USD, 2300.0),
                new Transaction(Currency.GBP, 9900.0),
                new Transaction(Currency.EUR, 1100.0),
                new Transaction(Currency.JPY, 7800.0),
                new Transaction(Currency.CHF, 6700.0),
                new Transaction(Currency.EUR, 5600.0),
                new Transaction(Currency.USD, 4500.0),
                new Transaction(Currency.CHF, 3400.0),
                new Transaction(Currency.GBP, 3200.0),
                new Transaction(Currency.USD, 4600.0),
                new Transaction(Currency.JPY, 5700.0),
                new Transaction(Currency.EUR, 6800.0) );
        transactions.stream()
                .collect(Collectors.groupingBy(Transaction::getCurrency))
                .forEach((c,list)-> System.out.println(c+":"+list));
    }
}