Java - 将 LinkedHashMap 键/值放入相应列表的简单方法？
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Java - Simple way to put LinkedHashMap keys/values into respective Lists?
提问by
I have a LinkedHashMap < String, String > map.
我有一个LinkedHashMap < String, String > map.
List < String > keyList;
List < String > valueList;
map.keySet();
map.values();
Is there an easy way to populate keyList from map.keySet() and valueList from map.values(), or do I have to iterate?
有没有一种简单的方法可以从 map.keySet() 填充 keyList 和从 map.values() 填充 valueList，或者我必须迭代？
采纳答案by Bozho
Most collections accept Collectionas a constructor argument:
大多数集合都接受Collection作为构造函数参数：
List<String> keyList = new ArrayList<String>(map.keySet());
List<String> valueList = new ArrayList<String>(map.values());
回答by Victor Parmar
For sure!
当然！
keyList.addAll(map.keySet());
Or you could pass it at the time of creation as well
或者你也可以在创建时传递它
List<String> keyList = new ArrayList<String>(map.KeySet());
http://download.oracle.com/javase/1.4.2/docs/api/java/util/ArrayList.html
http://download.oracle.com/javase/1.4.2/docs/api/java/util/ArrayList.html
回答by Razib
A different approach using java 8 -
使用 java 8 的不同方法 -
List<String> valueList = map.values().stream().collect(Collectors.toList());
List<String> keyList = map.keySet().stream().collect(Collectors.toList());
Notes:
笔记：
stream()- returns sequence ofObjectconsidering collection (here themap) as sourceCollectors- Collectors are used to combining the result of processing on the elements of a stream.
stream()- 返回Object考虑集合（这里是map）作为源的 序列Collectors- 收集器用于组合流元素的处理结果。
