Simple way to sort strings in the (case sensitive) alphabetical order

问题

I need to sort list of strings in the alphabetical order:

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

A common way to do it is to use comparator:

Collections.sort(list, String.CASE_INSENSITIVE_ORDER);

The problem of the CaseInsensitiveComparator that “AA” is equals to “aa”. Strings appear in the result according to the order of adding for the same values, and it is not correct:

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

回答1:

If you don't want to add a dependency on Guava (per Michael's answer) then this comparator is equivalent:

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);

And I think it is just as easy to understand and code ...

The last 4 lines of the method can written more concisely as follows:

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

回答2:

The simple way to solve the problem is to use ComparisonChain from Guava 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);

The first comparator from the chain will sort strings according to the case insensitive order, and the second comparator will sort strings according to the case insensitive order. As excepted strings appear in the result according to the alphabetical order:

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

回答3:

I recently answered a similar question here. Applying the same approach to your problem would yield following solution:

list.sort(
  p2Ord(stringOrd, stringOrd).comap(new F<String, P2<String, String>>() {
    public P2<String, String> f(String s) {
      return p(s.toLowerCase(), s);
    }
  })
);

回答4:

Simply use

java.util.Collections.sort(list)

without String.CASE_INSENSITIVE_ORDER comparator parameter.

回答5:

import java.util.Arrays;
import java.util.Scanner;

public class Test3 {
    public static void main(String[] args) {

        String a;
        String b;
        try (Scanner scan = new Scanner(System.in)) {
            a = scan.next();
            b = scan.next();
        }
        boolean ret = isAnagram(a, b);
        System.out.println((ret) ? "Anagrams" : "Not Anagrams");

    }

    static boolean isAnagram(String a, String b) {
        int l1 = a.length();
        int l2 = b.length();
        boolean rat = false;

        if (l1 <= 50) {
            if (l1 == l2) {

                char[] chars1 = a.toLowerCase().toCharArray();
                char[] chars2 = b.toLowerCase().toCharArray();
                Arrays.sort(chars1);
                Arrays.sort(chars2);
                String Ns1 = new String(chars1);
                String Ns2 = new String(chars2);
                if (Ns1.equals(Ns2)) {
                    rat = true;
                }
            }
        }
        return rat;
    }
}

来源：https://stackoverflow.com/questions/11176227/simple-way-to-sort-strings-in-the-case-sensitive-alphabetical-order

标签

java

string

comparator

alphabetical