如何排序字母数字字符串 [英] How to sort Alphanumeric String

问题描述

我在排序包含整数的字符串时遇到问题。如果我使用下面的代码，我会得到如下排序：
1some，2some，20some，21some，3some，some

I have a problem with sorting strings which include integers. If I use the below code I get sorting like: 1some, 2some, 20some, 21some, 3some, some

但是我希望它排序如下：
1some，2some，3some，20some，21some，some

However I want it sorted like: 1some, 2some, 3some, 20some, 21some, some

我该怎么做？

谢谢！

Collections.sort(selectedNodes,
    new Comparator<DefaultMutableTreeNode>() {
    @Override
    public int compare(DefaultMutableTreeNode o1,
        DefaultMutableTreeNode o2) {
        return o1.getUserObject().toString()
            .compareTo(o2.getUserObject().toString());
    }
    });

推荐答案

这是一个关于如何做的自包含示例这个（没有特别优化）：

Here is a self-contained example on how to do this (not particularly optimized):

final Pattern p = Pattern.compile("^\\d+");
String[] examples = { 
   "1some", "2some", "20some", "21some", "3some", "some", "1abc", "abc"
};
Comparator<String> c = new Comparator<String>() {
    @Override
    public int compare(String object1, String object2) {
        Matcher m = p.matcher(object1);
        Integer number1 = null;
        if (!m.find()) {
            return object1.compareTo(object2);
        }
        else {
            Integer number2 = null;
            number1 = Integer.parseInt(m.group());
            m = p.matcher(object2);
            if (!m.find()) {
                return object1.compareTo(object2);
            }
            else {
                number2 = Integer.parseInt(m.group());
                int comparison = number1.compareTo(number2);
                if (comparison != 0) {
                    return comparison;
                }
                else {
                    return object1.compareTo(object2);
                }
            }
        }
    }
};
List<String> examplesList = new ArrayList<String>(Arrays.asList(examples));
Collections.sort(examplesList, c);
System.out.println(examplesList);

输出

[1abc, 1some, 2some, 3some, 20some, 21some, abc, some]

解释

• 该示例使用常量模式推断一个数字是否在 String 的起始位置。


• 如果第一个不存在 String ，它将其与第二个进行比较。


• 如果确实存在于第一个中，它会检查第二个。


• 如果第二个不存在，则按原样比较两个 String ，再次


• 如果在两者中，它比较 Integer 而不是整个 String s，因此导致数字比较而不是词典编纂


• 如果数字比较相同，则返回整个 String s的字典比较（谢谢 MihaiC 发现这一个）

• The example uses a constant Pattern to infer whether a number is in the String's starting position.
• If not present in the first String, it compares it as is to the second.
• If present indeed in the first, it checks the second.
• If not present in the second, it compares the two Strings as is, again
• If present in both, it compares the Integers instead of the whole Strings, hence resulting in a numerical comparison rather than a lexicographical one
• If the number compare identical, it goes back to lexicographic comparison of the whole Strings (thanks MihaiC for spotting this one)

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