while(line.contains("^")) loop not breaking

Question

this is my class:

import java.io.*;

public class Test
{
  public static void main(String[] args) throws FileNotFoundException, IOException
  {
    BufferedReader br = new BufferedReader(new FileReader("file2.txt"));
    BufferedWriter bw = new BufferedWriter(new FileWriter("file.txt"));

    int i = 0;
    String line;

    while ((line = br.readLine()) != null) {
      while(line.contains("^")) {
        i ++;
        line = line.replaceFirst("^", Integer.toString(i));
      }
      bw.write(line + "\n");
    }
    br.close();
    bw.close();
  }
}

the file2.txt and file.txt are exactly the same and I want to make the lines that look like

<wpt lat="26.381418638" lon="-80.101236298"><ele>0</ele><time> </time><name>Waypoint #^</name><desc> </desc></wpt>

to look like

<wpt lat="26.381418638" lon="-80.101236298"><ele>0</ele><time> </time><name>Waypoint #5</name><desc> </desc></wpt>

When I run it though, it goes on an infinite loop. Any advice will help. Thanks!

Answer 1

line = line.replaceFirst("^", Integer.toString(i));

replaceFirst's first argument is a regular expression, and "^" as a regular expression means "the start of the string". So this command just keeps prepending values to the start of the string, and never removes any circumflexes. Instead, you should write:

line = line.replaceFirst("\\^", Integer.toString(i));