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This article will explain in detail the example analysis of the group method in the regular expression Matcher class. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.

0 | 1Pattern and Matcher

Under the java.util.regex package

Pattern (pattern class): the object used to express and state the pattern to be searched for. Pattern.compile (pattern) pattern is the regular expression that you write.

Matcher (matcher class): the object that really affects the search. The above Pattern.compile (pattern) gets a Pattern object called r. R.matcher (line) line is the string you need to match. This results in an object of Matcher.

PatternSyntaxException: an exception is thrown when an illegal search pattern is encountered.

0 | 1 regular expression syntax

In some languages, one backslash\ is sufficient for escape, but two\\ backslashes are required in Java. Indicates the function of escape. The description and meaning of some characters in regular expressions. For details, please see runoob

| 0 | Code on 1 |

Now my regular expression is (/ / d +) ([amurz] +) (/ / d +)

/ / d + means to match at least one number

[amurz] + means to match at least one character

The string you need to specify is "123ra9040 123123aj234 adf12322ad 222jsk22"

The code is as follows:

Public static void main (String args []) {/ / find String line = "123ra9040 123123aj234 adf12322ad 222jsk22" in the string in the specified mode; String pattern = "(\\ d +) ([Amurz] +) (\\ d +)"; / / String pattern1 = "([\ u4E00 -\\ u9FA5] + |\\ w+)"; / / create Pattern object Pattern r = Pattern.compile (pattern) / / now create the matcher object Matcher m = r.matcher (line); int I = 0; / / whether m.find finds the qualified string while (m.find ()) {/ / gets the matching data System.out.println ("- I =" + I); System.out.println ("Found value:" + m.group (0)) System.out.println ("Found value:" + m.group (1)); System.out.println ("Found value:" + m.group (2)); System.out.println ("Found value:" + m.group (3)); System.out.println ("|"); System.out.println (");}}

Output:

-iTun0

Found value: 123ra9040

Found value: 123

Found value: ra

Found value: 9040

| |

-iTun1

Found value: 123123aj234

Found value: 123123

Found value: aj

Found value: 234

| |

-iTun2

Found value: 222jsk22

Found value: 222

Found value: jsk

Found value: 22

| |

Group (0) corresponds to ((/ / d +) ([amurz] +) (/ / d +)) 123ra9040

The output data of group (2) is the data matched in group (0), that is, ([a Mizz] +) matches to data ra.

The output data of group (3) is the data matched in group (0), that is, (/ / d +) matches to data 9040.

| 0 | 1 summary |

Group (0) in the Matcher class represents a conditional string in a regular expression.

Group (1) in the Matcher class represents the string in the first () of the qualified string in the regular expression.

Group (2) in the Matcher class represents the string in the second () of the qualified string in the regular expression.

Group (3) in the Matcher class represents the string in the third () of the qualified string in the regular expression.

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