以(区分大小写)字母顺序对字符串进行排序的简单方法

Question

我需要按字母顺序对字符串列表进行排序:

List<String> list = new ArrayList();
list.add("development");
list.add("Development");
list.add("aa");
list.add("AA");
list.add("Aa");

一种常见的方法是使用比较器:

Collections.sort(list, String.CASE_INSENSITIVE_ORDER);

CaseInsensitiveComparator的问题是"AA"等于"aa".字符串根据相同值的添加顺序出现在结果中,并且不正确:

"aa","AA","Aa","development","Development"

Answer 1

如果您不想添加对Guava的依赖(根据Michael的回答),那么这个比较器是等价的:

private static Comparator<String> ALPHABETICAL_ORDER = new Comparator<String>() {
    public int compare(String str1, String str2) {
        int res = String.CASE_INSENSITIVE_ORDER.compare(str1, str2);
        if (res == 0) {
            res = str1.compareTo(str2);
        }
        return res;
    }
};

Collections.sort(list, ALPHABETICAL_ORDER);

我认为这很容易理解和编码......

该方法的最后4行可以更简洁地写成如下:

        return (res != 0) ? res : str1.compareTo(str2);

Answer 2

解决问题的简单方法是使用Guava中的ComparisonChain http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/collect/ComparisonChain.html

private static Comparator<String> stringAlphabeticalComparator = new Comparator<String>() {
        public int compare(String str1, String str2) {
            return ComparisonChain.start().
                                compare(str1,str2, String.CASE_INSENSITIVE_ORDER).
                                compare(str1,str2).
                                result();
         }
 };
Collections.sort(list, stringAlphabeticalComparator);

链中的第一个比较器将根据不区分大小写的顺序对字符串进行排序,第二个比较器将根据不区分大小写的顺序对字符串进行排序.由于例外字符串根据字母顺序出现在结果中:

"AA","Aa","aa","Development","development"