英文:
Remove one value in hashmap instead of all values and key
问题
我有一个哈希映射，其结构为 Map<String, Set<String>> tasks。在 tasks 中，我有一些键，而这些键又包含了一些值，不仅仅是一个值。
我想要从哈希映射中删除具有给定键的某个值，但同时保留其他值。
我的意思是像这样 release = ["fix bug 1", "fix bugs 2" , "implement feature X"]。现在 release 是一个键（String 类型），包含了值（Set<String> 类型）"fix bug 1", "fix bugs 2" , "implement feature X"。我想要修改 release 如下：
release = ["implement feature X"]
我该如何删除两个值？谢谢
英文:
I have a hashmap which is Map<String, Set<String>> tasks . Inside the tasks I have some keys and keys have some values, not just a value.
I would like remove a value from hashmap with given key but I also want to keep other values there.
I mean like this release = ["fix bug 1", "fix bugs 2" , "implement feature X"] . now release is key(in String type) and has values(in Set<String> type) "fix bug 1", "fix bugs 2" , "implement feature X" .. I would like to modified release like this :
release = ["implement feature X"]
how can I remove 2 values??? Thanks
答案1
得分: 1
利用这个键，你可以获取到想要的集合，然后移除特定的值：
map.get("key").removeIf(s -> s.equals("value"));
map.get("key").removeIf(s -> s.equals("value") || s.equals("value1"));
你可以进行更多的组合。不需要更新 HashMap，它持有集合的引用，无论对集合做了什么操作，HashMap 都会知道。
英文:
Using the key you can get the Set you want and then remove the value:
map.get("key").removeIf(s -> s.equals("value"));
map.get("key").removeIf(s -> s.equals("value") || s.equals("value1"));
You can do more combinations.
There is not need to update the HashMap. it has the reference of Set and whatever happens to Set the HashMap knows it.
答案2
得分: 0
你的地图仅包含对集合的引用，因此你可以直接修改集合，地图会反映出这些更改。
这意味着你可以这样做：
tasks.get("release").removeAll(Arrays.asList("fix bug 1", "fix bug 2"));
甚至可以这样做：
tasks.get("release").retainAll(Arrays.asList("implement feature X"));
英文:
Your Map only contains references to Sets, so you can modify the Sets directly and the changes will be seen by the Map.
Which means you can do:
tasks.get("release").removeAll(Arrays.asList("fix bug 1", "fix bug 2"));
Or even:
tasks.get("release").retainAll(Arrays.asList("implement feature X"));
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