如何在其末尾用cross（x）按钮创建EditText？(How to create EditText with cross(x) button at end of it?)

 这些正则表达式是等效的（为了匹配目的）： 
 
 
 
 /^(7|8|9)\d{9}$/ 
 
 
 /^[789]\d{9}$/ 
 
 
 /^[7-9]\d{9}$/ 
 
 
 说明： 
 
 
 
 (a|b|c)是正则表达式“OR”，意思是“a或b或c”，尽管OR所需的括号的存在也捕获数字。 要严格等效，您将编码(?:7|8|9)使其成为非捕获组。 
 
 
 [abc]是一个“字符类”，意思是“来自a，b或c的任何字符”（字符类可以使用范围，例如[ad] = [abcd] ） 
 
 
 这些正则表达式相似的原因是字符类是“或”（但仅适用于单个字符）的缩写。 在一个替代中，你也可以做一些像(abc|def)这样的东西，它不会转换成一个字符类。 

These regexes are equivalent (for matching purposes):
 
 
 
/^(7|8|9)\d{9}$/
 
 
/^[789]\d{9}$/
 
 
/^[7-9]\d{9}$/
 
 
The explanation:
 
 
 
(a|b|c) is a regex "OR" and means "a or b or c", although the presence of brackets, necessary for the OR, also captures the digit. To be strictly equivalent, you would code (?:7|8|9) to make it a non capturing group.
 
 
[abc] is a "character class" that means "any character from a,b or c" (a character class may use ranges, e.g. [a-d] = [abcd])
 
 
The reason these regexes are similar is that a character class is a shorthand for an "or" (but only for single characters). In an alternation, you can also do something like (abc|def) which does not translate to a character class.