Does Java String.getBytes(“UTF-8”) preserve lexicograhpical order?

Question

如果我有一个字典排序的Java字符串[s1,s2,s3,s4, ...., sn] ，然后使用UTF-8编码将每个字符串转换为字节数组bx = sx.getBytes("UTF-8") ，是字节数组的列表[b1,b2,b3,...bn]也是字典排序的？

Answer 1

Yes. According to RFC 3239 :

The byte-value lexicographic sorting order of UTF-8 strings is the same as if ordered by character numbers. Of course this is of limited interest since a sort order based on character numbers is almost never culturally valid.

As Ian Roberts pointed out, this applies for " true UTF-8 (such as String.getBytes will give you)", but beware of DataInputStream 's fake UTF-8 , which will sort [U+000000] after [U+000001] and [U+00F000] after [U+10FFFF].

Answer 2

You get a list/array of objects X, in a given orden.

You create a new list/array Y of such objects, applying a method.

Y will have the ordering that you created it with (normally you will have just kept X order). No reordering happens.

Also, lexycographical ordering for a byte[] is meaningless.