使用正则表达式从字符串中提取所需的单词

Question

  if (txt.matches("Who is the(.*)")) {
        String re1=".*?";   
        String re2="(?:[a-z][a-z]+)";   
        String re3=".*?";
        String re4="(?:[a-z][a-z]+)";   
        String re5=".*?";   
        String re6="(?:[a-z][a-z]+)";   
        String re7=".*?";   
        String re8="((?:[a-z][a-z]+))"; 
        String re9=".*?";   
        String re10="(?:[a-z][a-z]+)";  
        String re11=".*?";  
        String re12="((?:[a-z][a-z]+))";

        Pattern p = Pattern.compile(re1+re2+re3+re4+re5+re6+re7+re8+re9+re10+re11+re12,Pattern.CASE_INSENSITIVE | Pattern.DOTALL);
        Matcher m = p.matcher(txt);
        if (m.find())
        {
            String word1=m.group(1);
            String word2=m.group(2);
            String z=word2.toString()+"&&"+word1.toString();
            System.out.println(z);
    }
    }

我从网上获得了这段代码，但不理解它如何从字符串中提取少数必需单词的代码 "txt"。特别是 re1 和 re2 是什么……等等。对于任何东西-"Who is the HOD of ECE"它returns ECE&&HOD。有人可以解释一下代码吗...请帮忙。

Answer 1

查看代码中的注释以解释此代码的作用。 re1 和 re2 所做的只是创建一个字符串，然后将其加入代码的 Patern.compile() 部分。当你有 2 个字符串，如 String foo = "foo" 和 String bar = "bar" 并且你执行 String foobar = foo + bar; 时，输出是 foobar。

 //If the String object "txt" matches the given regex, which in this case is "Who is the(.*)"
  if (txt.matches("Who is the(.*)")) {
        String re1=".*?";   
        String re2="(?:[a-z][a-z]+)";   
        String re3=".*?";
        String re4="(?:[a-z][a-z]+)";   
        String re5=".*?";   
        String re6="(?:[a-z][a-z]+)";   
        String re7=".*?";   
        String re8="((?:[a-z][a-z]+))"; 
        String re9=".*?";   
        String re10="(?:[a-z][a-z]+)";  
        String re11=".*?";  
        String re12="((?:[a-z][a-z]+))";


        //this creates a pattern using the above strings.
        Pattern p = Pattern.compile(re1+re2+re3+re4+re5+re6+re7+re8+re9+re10+re11+re12,Pattern.CASE_INSENSITIVE | Pattern.DOTALL);

        //creates matcher object from the String object "txt"
        Matcher m = p.matcher(txt);

        //m.find() "Attempts to find the next subsequence of the input sequence that matches the pattern.", if it does...
        if (m.find())
        {
            //m.group "Returns the input subsequence matched by the previous match."
            String word1=m.group(1);
            String word2=m.group(2);
            //creates a string
            String z=word2.toString()+"&&"+word1.toString();
            //prints out string
            System.out.println(z);
    }
    }

Source for quotes

使用正则表达式从字符串中提取所需的单词

Extraction of required words from a string using regular expression

java

regex

pattern-matching