[英]java Regular expressions about line contains multiple characters
Iam new to java and I would like to make a question about java regular expression. 我是Java的新手,我想就Java正则表达式提出一个问题。
How can I check if a line contains only a specific string followed by any operator. 如何检查行是否仅包含特定字符串,后接任何运算符。 Also, and previous of the string does not contains "//".
另外,字符串的前一个不包含“ //”。
For example, if line is: 例如,如果line是:
//x; -> does not matches the criteria
x++; ->matches
x--; ->matches
x=1; ->matches
(x,y) ->matches
(x1,y) ->does not matches because we want only x not x1
x = 1 ; ->matches
Thanks in advance. 提前致谢。
You can use this negative lookahead based regex: 您可以使用以下基于负前瞻的正则表达式:
^(?:(?!//).)*\bx\b.*
In Java use: 在Java中使用:
boolean valid = str.matches("^(?:(?!//).)*\\bx\\b");
RegEx Breakup: 正则表达式分解:
^ # line start
(?:(?!//).)* # negative lookahead, match any char that doesn't have // at next position
\b # word boundary
x # literal x
\b # word boundary
.* # match every thing till end
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