public class UpdateFiles {
public static void main(String[] args) throws IOException{
String fileName = "c:\\works\\Java\\baseFile.txt";
File file = new File(fileName);
String tmpFileName = file.getAbsolutePath() + Long.toString(System.currentTimeMillis());
File tmpFile = new File(tmpFileName);
file.renameTo(tmpFile);
file.createNewFile();
BufferedReader br = new BufferedReader(new FileReader(tmpFile));
FileWriter out = new FileWriter(file);
String line;
Pattern p = Pattern.compile("pattern");
Matcher m ;
while((line = br.readLine()) != null ){
m = p.matcher(line);
line = m.replaceAll("replace");
out.write(line + "\r\n");
}
br.close();
tmpFile.delete();
out.close();
}
}