2 replies to this topic

[vachovsky]

So...

Task:

I have some phrase. the phrase contains 2 words. Phrase is devided into two words with next symbols:

[\s]*

How can i find the phrase using regular expression?

This code doesn't work on a file:

// file: Main.java

class 





Main {

}

      Pattern pattern = Pattern.compile("class[\\s]+Main");


      BufferedReader input = new BufferedReader ( new FileReader( "Main.java" ) );


      int id = 0;


      for ( String line = input.readLine(); line != null; line = input.readLine() )

      {

         ++id;


         Matcher matcher = pattern.matcher( line );



         if ( matcher.find() )

         {

            System.out.println("number = " + id );


            System.out.println("start = " + matcher.start() );

            System.out.println("end   = " + matcher.end() );

            System.out.println( );

         }

      }


      input.close();

  

[discomonk]

The reason your code didn't work is because you are trying to match a multi-line pattern against each line separately. To fix it, you would have to buffer all of the input lines using StringBuilder and then match against them together, like the modified version of your code:

public class Regexp {


	public static void main(String[] args) throws IOException {

		Pattern pattern = Pattern.compile("class[\\s]+Main");


		BufferedReader input = new BufferedReader ( new FileReader( "Main.java" ) );


		StringBuilder bldr = new StringBuilder(1024);

		for ( String line = input.readLine(); line != null; line = input.readLine() )

		{

			bldr.append(line);

		}

		

		Matcher matcher = pattern.matcher( bldr.toString() );



		if ( matcher.find() )

		{

			

			System.out.println("start = " + matcher.start() );

			System.out.println("end   = " + matcher.end() );

			System.out.println( );

		}



		input.close();


	}

}

[vachovsky]

[english]
Yes, this solution is obvious. But, the file is too big, >= 400 mb ....

I think, that i will read file using something like

char c = scanner.nextChar()

and

 if ( c == "class".charAt(0) ) { ... } 

[russian]
Да, это решение очевидно. Но файл слишком большой, чтоб всё его содержимое ложить в строчку. Минимальный размер файла в 400 mb...