Java: Regex

在networking field工作約十年, 都是對開Cisco, H3C, Juniper and so on 既產品, 如果唔係SDN依樣野,我諗都唔會對programming 有番興趣, 好了, 學習既動力都是由興趣開始, 就由Java開始吧.

和Java Script相比, Java的regex比較難明白, 在不斷網上尋找不同的例子下, 終於寫下下例的code.

import java.io.*;
import java.util.regex.*;

public class regex {
	public static void main(String[] args) throws IOException {
		
		String s = "";
		String line;
		String ss;
		Pattern p = Pattern.compile("This.*y", Pattern.DOTALL);
			
		File file = new File("C:\\Users\\XXX\\workspace\\Java-Test\\src\\old.txt");
		FileReader fr = new FileReader(file);
		BufferedReader br = new BufferedReader(fr);
		while ((line = br.readLine()) != null) {
		  s += line + "\r\n";
		   }
		br.close();
		Matcher m = p.matcher(s);
		ss = m.replaceAll("Replaced");
		FileWriter wr = new FileWriter("C:\\Users\\XXX\\workspace\\Java-Test\\src\\new.txt");
		wr.write(ss);
		wr.close();
		System.out.println("Done");
		}
	}

old.txt
Java Testing
This is good day to learn
Really
End

new.txt
Java Testing
Replaced
End