Java code does not recognize ctrl-m(^M) but works fine for other ctrl-characters(^Q,^A,^T etc) Linux

Question

I have a requirement where I need to remove two specific control characters: ^@ and ^M, from the incoming data in Java on a Linux box.

Below mentioned parts work as expected:

String s;
s = s.replaceAll("\\x00","as");
s = s.replaceAll("\\000", "as");

but these don't:

s = s.replaceAll("\\015", "as"); //Octal
s = s.replaceAll("\\x0D", "as"); //Hex

I have tried all available representations(octal/hex/unicode) including \r to represent ^M in my code but it does not work. As mentioned above everything works fine for other control characters.

Please suggest if there's anything that I haven't tried or missed.

Edit: Providing the implementable code as requested.

public class sampSC {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("./samp1.txt"));

        try {
            StringBuilder sb = new StringBuilder();
            String line = br.readLine();

            while (line != null) {
                sb.append(line);
                line = br.readLine();
            }

            String s = sb.toString();
            System.out.println(s);
            s = s.replaceAll("\\00", "sb"); //works
            System.out.println(s);
            s = s.replaceAll("\\x11", "s23b"); //works
            System.out.println(s);
            s = s.replaceAll("\\r$", "aa"); //doesn't work
            System.out.println(s);
        } finally {
            br.close();
        }
    }
}

Answer 1

To summarize the comments: the file is read in line by line with BufferedReader.readLine(). The readline strips off the line break character ^M (\r) so it never makes it into the String that is later searched.