如何将集合转换为列表中的JAVA? [英] How convert a Collection to List in JAVA?
问题描述
我使用 Apache Collections
库中的 TreeBidiMap
。我想对 doubles
的值排序。
I am using TreeBidiMap
from the Apache Collections
library. I want to sort this on the values which are doubles
.
我的方法是检索 Collection
的值使用:
集合coll = themap.values();
$ b $
主要问题:我现在想知道如何转换/投射(不确定是否正确) coll code>转换为
列表
以便可以排序?
My method is to retrieve a Collection
of the values using:
Collection coll = themap.values();
Which naturally works fine.
Main Question: I now want to know how I can convert/cast (not sure which is correct) coll
into a List
so it can be sorted?
然后,我打算遍历排序的 List
对象,它应该按顺序,
使用
(
themap
code>其中迭代器将在 doubles
的列表上。
I then intend to iterate over the sorted List
object, which should be in order and get the appropriate keys from the TreeBidiMap
(themap
) using themap.getKey(iterator.next())
where the iterator will be over the list of doubles
.
推荐答案
List list = new ArrayList(coll);
Collections.sort(list);
正如Erel Segal Halevi所说,如果coll已经是一个列表,你可以跳过第一步。但是这将取决于TreeBidiMap的内部。
As Erel Segal Halevi says below, if coll is already a list, you can skip step one. But that would depend on the internals of TreeBidiMap.
List list;
if (coll instanceof List)
list = (List)coll;
else
list = new ArrayList(coll);
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