Java中的词典顺序 [英] Lexicographic Order in Java

问题描述

如何在Java中定义字典顺序，特别是在引用特殊字符时，例如！，。等等？

How is the lexicographic order defined in Java especially in reference to special characters like !, . and so on?

可以在这里找到示例性订单

但Java如何定义它的顺序？我问，因为我在Java和Oracle上对字符串进行排序并得出不同的结果，并且找不到字典顺序的规范。

But how does Java define it's order? I ask because I'm sorting Strings on Java and on Oracle and come up with different results and can't find the specification for the lexicographic order.

推荐答案

来自 String.compareTo ：

按字典顺序比较两个字符串。比较基于字符串中每个字符的Unicode值。

Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.

和

这是词典排序的定义。如果两个字符串不同，则它们在某个索引处具有不同的字符，这些字符串是两个字符串的有效索引，或者它们的长度不同，或者两者都有。如果它们在一个或多个索引位置具有不同的字符，则令k为最小的索引;然后，通过使用<来确定位置k处的字符具有较小值的字符串。运算符，按字典顺序排在另一个字符串之前。在这种情况下，compareTo返回两个字符串中位置k处两个字符值的差异[...]

This is the definition of lexicographic ordering. If two strings are different, then either they have different characters at some index that is a valid index for both strings, or their lengths are different, or both. If they have different characters at one or more index positions, let k be the smallest such index; then the string whose character at position k has the smaller value, as determined by using the < operator, lexicographically precedes the other string. In this case, compareTo returns the difference of the two character values at position k in the two string [...]

所以基本上，它将每个字符串视为一系列16位无符号整数。没有文化意识，不了解复合角色等。如果你想要更复杂的排序，你应该看看 Collat​​or 。

So basically, it treats each string like a sequence of 16-bit unsigned integers. No cultural awareness, no understanding of composite characters etc. If you want a more complex kind of sort, you should be looking at Collator.

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