基于key对树图进行排序，其中key是可变的 [英] sorting treemap based on key, where key is variable

问题描述

我想基于key是变量的键对树映射进行排序，因此排序应该基于变量值，我们如何实现这一点？我希望在构建的排序方法中使用rathar通过代码实现它，任何回复示例都有很大的帮助。

I want to sort the tree map based on the key where key is a variable,so sorting should be based on variable value, How can we achieve this? I want use in built sort method rathar implementing it through code, any reply with example is of great help.

推荐答案

TreeMap （实现 SortedMap ）以正确的顺序自动存储密钥：

TreeMap (which implements SortedMap) stores automatically the keys in the correct order:

Map<Integer, String> map = new TreeMap<Integer, String>();
map.put(1, "one");
map.put(3, "three");
map.put(2, "two"); 
// prints one two three   
for(Integer key : map.keySet()) {
    System.out.println(map.get(key));
}

作为键类型（在这种情况下整数）你可以使用任何实现 可比较 （或者您可以提供 TreeMap 时，util / Comparator.htmlrel =noreferrer> Comparator

As Key-Type (in that case Integer) you can use any class which implements Comparable (or you can provide a Comparator when creating the TreeMap)

编辑：好的，这是一个如何重新映射地图的建议。

Okay, here is a suggestion how to re-map your map.

Map<Integer, String> oldMap; // get oldMap from somewhere
// Prepare remapping
Map<Integer, String> newMap = new TreeMap<Integer, String>();
Map<Integer, Integer> keyMap = new HashMap<Integer, Integer>();
// Store a new key for each old key
keyMap.put(oldKey, newKey);
// fill the newMap
for(Integer oldKey : keyMap.keySet()) {
    newMap.put(keyMap.get(oldKey), oldMap.get(oldKey));
}
oldMap = newMap; // if needed

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