如何在Java中按两个字段排序? [英] How to sort by two fields in Java?

问题描述

我有对象数组person (int age; String name;).

如何按名称和年龄的字母顺序对这个数组进行排序?

How can I sort this array alphabetically by name and then by age?

你会使用哪种算法?

推荐答案

您可以使用 Collections.sort 如下:

private static void order(List<Person> persons) {

    Collections.sort(persons, new Comparator() {

        public int compare(Object o1, Object o2) {

            String x1 = ((Person) o1).getName();
            String x2 = ((Person) o2).getName();
            int sComp = x1.compareTo(x2);

            if (sComp != 0) {
               return sComp;
            } 

            Integer x1 = ((Person) o1).getAge();
            Integer x2 = ((Person) o2).getAge();
            return x1.compareTo(x2);
    }});
}

List 现在按姓名排序，然后按年龄排序.

List<Persons> is now sorted by name, then by age.

String.compareTo 按字典顺序比较两个字符串" - 来自 文档.

String.compareTo "Compares two strings lexicographically" - from the docs.

Collections.sort 是原生 Collections 库中的静态方法.它进行实际的排序，您只需要提供一个 Comparator 来定义应该如何比较列表中的两个元素:这是通过提供您自己的 compare 方法实现来实现的.

Collections.sort is a static method in the native Collections library. It does the actual sorting, you just need to provide a Comparator which defines how two elements in your list should be compared: this is achieved by providing your own implementation of the compare method.

这篇关于如何在Java中按两个字段排序?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！