遍历带有arraylist的hashmap?

问题描述

所以我有一个带有数组列表的基本哈希图:

So I have a basic hashmap with an arraylist:

Map<Text, ArrayList<Text>> map = new HashMap<Text, ArrayList<Text>>();

说我有一个键值对:键:Apple，值:橙色，红色，蓝色

Say I have a key value pair: Key: Apple, Value: orange, red, blue

我已经了解了如何遍历以打印密钥，其值如下所示:苹果，橙，红，蓝

I already understand how to iterate through to print the key and it’s values like so:Apple, orange, red, blue

但是有一种方法可以拆分值/通过内部ArrayList进行迭代，并分别打印键/值对3次/用每个值分别打印键，如:

but is there a way to break up the values/iterate through the inner ArrayList and print the key/value pair three separate times/print the key with each value separately like:

Apple orange
Apple red
Apple blue

推荐答案

使用简单的for循环，将是:

Using simple for loops, this would be:

for (Map.Entry<Text, ArrayList<Text>> entry : map.entrySet()) {
    for (Text text : entry.value()) {
        System.out.println(entry.key() + " " + text);
    }
}

在功能上进行相同的操作:

Doing the same in a functional way:

map.forEach((key, valueList) ->
    valueList.forEach(listItem -> System.out.println(key + " " + listItem)
));

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