Untitled

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class App {

    public static String readHTML() {
        StringBuilder contentBuilder = new StringBuilder();
        try {
            //take input
            BufferedReader in = new BufferedReader(new FileReader("./src/den.html"));
            String str;
            while ((str = in.readLine()) != null) {
                //append to the string builder
                contentBuilder.append(str);
            }
            in.close();

            String content = contentBuilder.toString();
            content = content.toUpperCase();

            //find the body
            Pattern pattern = Pattern.compile("<BODY.*?>(.*?)</BODY>");
            Matcher matcher = pattern.matcher(content);
            if (matcher.find()) {
                String body = matcher.group(1);
            return body;
            }

            return null;
        } 
        catch (IOException e) {
            System.out.println(e);
            return null;
        }
        
    }
    public static void main(String[] args) throws Exception {
        String input = readHTML();

        // find the run time of the program
        // long start = System.currentTimeMillis();
        // long end = System.currentTimeMillis();
        // System.out.println("Time: " + (end - start) + "ms");
    }
}