如何使用季节和年份对字符串的ArrayList进行排序？
我有一个未排序的 ArrayList 的季节和年份字符串，如下所示：
["Summer 2020", "Autumn 2018", "Spring 2019", "Autumn 2019", "Winter 2018", "Summer 2018", "Winter 2020", "Spring 2018"]
此列表的正确排序如下：
["Winter 2018", "Spring 2018", "Summer 2018", "Autumn 2018", "Spring 2019", "Autumn 2019", "Winter 2020", "Summer 2020"]
我怎样才能实现这个命令？一年中的季节顺序是 2021 年冬季、2021 年春季、2021 年夏季、2021 年秋季，并且列表中不一定存在每年的所有季节。
回答
您需要实现一个Comparator先按年份然后按季节排序的自定义。Anenum可用于轻松指定季节的顺序。
private static class SeasonComparator implements Comparator<String> {
private enum Season {
WINTER, SPRING, SUMMER, AUTUMN
}
@Override
public int compare(String s1, String s2) {
String[] arr1 = s1.split(" ");
String[] arr2 = s2.split(" ");
int year1 = Integer.parseInt(arr1[1]);
int year2 = Integer.parseInt(arr2[1]);
if (year1 != year2) {
return year1 - year2;
} else {
Season season1 = Season.valueOf(arr1[0].toUpperCase());
Season season2 = Season.valueOf(arr2[0].toUpperCase());
return season1.ordinal() - season2.ordinal();
}
}
}
public static void main(String[] args) {
List<String> seasons = new ArrayList<>(Arrays.asList("Summer 2020", "Autumn 2018",
"Spring 2019", "Autumn 2019", "Winter 2018", "Summer 2018", "Winter 2020", "Spring 2018"));
System.out.println("Unordered list:");
System.out.println(seasons);
seasons.sort(new SeasonComparator());
System.out.println("Sorted list:");
System.out.println(seasons);
}
输出
Unordered list:
[Summer 2020, Autumn 2018, Spring 2019, Autumn 2019, Winter 2018, Summer 2018, Winter 2020, Spring 2018]
Sorted list:
[Winter 2018, Spring 2018, Summer 2018, Autumn 2018, Spring 2019, Autumn 2019, Winter 2020, Summer 2020]