TreeMap如何排序 [英] TreeMap how does it sort
本文介绍了TreeMap如何排序的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
TreeMap
如何排序?例如,您具有以下地图:
How does the TreeMap
sort? say for example you have the following map:
TreeMap<String, Integer> treemap = new TreeMap<>();
treemap.put("lol", 1);
treemap.put("Marc", 2);
treemap.put("Jesper", 3);
Iterator ittwo = treemap.entrySet().iterator();
while (ittwo.hasNext()) {
Map.Entry pairs = (Map.Entry)ittwo.next();
System.out.println(pairs.getKey() + " = " + pairs.getValue());
ittwo.remove();
}
此输出为:
Jesper = 3
Marc = 2
lol = 1
那么如果不是按字母顺序是什么呢?
So if its not alphabetically what is it then?
推荐答案
它不仅按字母顺序,而且还区分大小写.
It is not only alphabetical, but it is also upper/down case sensitive.
TreeMap<String, Integer> treemap = new TreeMap<String, Integer>();
treemap.put("Lol", 1);
treemap.put("Marc", 2);
treemap.put("Jesper", 3);
treemap.put("lol1", 1);
treemap.put("marc1", 2);
treemap.put("jesper1", 3);
输出:
Jesper = 3
Lol = 1
Marc = 2
jesper1 = 3
lol1 = 1
marc1 = 2
因此,如果不需要它,可以使用自定义比较器,并以小写形式比较字符串:
So, if you don't need it, you can use your custom comparator, and compare string in lower case:
TreeMap<String, Integer> treemap = new TreeMap<String, Integer>(new Comparator<String>() {
public int compare(String o1, String o2) {
return o1.toLowerCase().compareTo(o2.toLowerCase());
}
});
treemap.put("Lol", 1);
treemap.put("Marc", 2);
treemap.put("Jesper", 3);
treemap.put("lol1", 1);
treemap.put("marc1", 2);
treemap.put("jesper1", 3);
输出:
Jesper = 3
jesper1 = 3
Lol = 1
lol1 = 1
Marc = 2
marc1 = 2
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