排序列表<T>对象的特定规则? [英] Sort List&lt;T&gt; of objects by a particular rule?

问题描述

我有这个清单:

List<Country> countryList = new ArrayList<Country>();

我想通过使用方法 getCountry() 按国家名称对国家进行排序.怎样才能做到这一点?

And I want to sort the countries by their name, by using the method getCountry(). How can achieve this?

更新:

public class Country implements Comparable
@Override
public int compareTo(Object another) {
    // TODO Auto-generated method stub
    return 0;
}

你能说出如何比较它们以按字符串排序吗?阿根廷，奥地利，巴西等

Can you tell how to compare them to get it sorted by Strings? Argentina, Austria, Brazil, etc.

推荐答案

有两种方式:

1. 让 Country 实施 java.util.Comparable 接口，用于在 Country 对象上定义自然排序，即创建对象本身知道"他们的顺序.然后您可以使用 Collections.sort(List) 或者只是从你的 List 切换到一个 SortedSet 实现，比如 TreeSet> (如果你不需要重复，Set 会丢弃重复)

1. Have Country implement the java.util.Comparable interface to define a natural ordering on your Country objects, i.e. make the objects themselves "know" their ordering. You can then use Collections.sort(List) or just switch from your List to a SortedSet implementation like TreeSet (if you don't need duplicates, a Set drops duplicates)

编写一个java.util.Comparator 定义一个强制排序并调用Collections.sort(List, Comparator) 或 (再次丢失重复项)选择 new TreeSet(Comparator).

实现这两个中的一个就足以解决您的问题——Comparable 和 Comparator 都可以结合使用，但是:使用 Comparator将覆盖 Comparable 定义的任何自然顺序.

Implementing one of these two is enough to solve your problem -- both Comparable and Comparator can be combined, though: using a Comparator will override any natural ordering defined by Comparable.

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