向正则表达式添加注释

//来 自 时代Java公众号 - N o w J a  v a . c o m


import java.io.File;

import java.io.FileReader;

import java.io.IOException;

import java.util.regex.Matcher;

import java.util.regex.Pattern;


public class Main {

  void m() throws Exception {

    CharSequence inputStr = "a b";

    String patternStr = "a b";


    // Compile without comments

    Pattern pattern = Pattern.compile(patternStr);

    Matcher matcher = pattern.matcher(inputStr);

    boolean matchFound = matcher.matches(); 

    System.out.println(matchFound);

    /*
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    */

    // Compile with comments

    pattern = Pattern.compile(patternStr, Pattern.COMMENTS);

    matcher = pattern.matcher(inputStr);

    matchFound = matcher.matches(); // false

    System.out.println(matchFound);


    // Use COMMENTS but include a character class with a space

    patternStr = "a  [\\ ]  b";

    pattern = Pattern.compile(patternStr, Pattern.COMMENTS);

    matcher = pattern.matcher(inputStr);

    matchFound = matcher.matches(); // true

    System.out.println(matchFound);

    

    // Use an inline modifier

    matchFound = pattern.matches("a b", inputStr); // true

    System.out.println(matchFound);

    matchFound = pattern.matches("(?x)a b", inputStr); // false

    System.out.println(matchFound);

    matchFound = pattern.matches("(?x)a [\\ ] b", inputStr); // true

    System.out.println(matchFound);

    matchFound = pattern.matches("(?x)a \\s b", inputStr); // true

    System.out.println(matchFound);

    matchFound = pattern.matches("a (?x:  b   )", inputStr); // true

    System.out.println(matchFound);


    // Tabs and newlines in the pattern are ignored as well

    matchFound = pattern.matches("(?x)a \t\n \\s b", inputStr); // true

    System.out.println(matchFound);

    // Read pattern from file

    try {

      File f = new File(