Replace specific string in a file while reading it

Question

Hi,
I am kind of an in between learner & intermediate programmer. I am trying to replace a specific string pattern in a file by reading it using BufferedReader & BufferedWriter. I tried it for 2 days. Can anyone give me a piece of code which reads a file line by line and replaces the specific string format with other? I tried replaceAll(regex,replacement). Nothing is working.

Answer 1

Hi Torajirou,
Thanks for the code. But, looks like
. But, looks like it is giving me a static method
problem. It says a static method should beaccessed
in a static way(f1.replace in main). Here is the
code. Can you help me with this?
import java.io.*;
public class FileReadWrite1{
public static void replace(File file, Stringregex,
String replacement) throws
FileNotFoundException,IOException {
     if (file == null) {
throw new IllegalArgumentException("File should
uld not be null.");
     if (!file.exists()) {
throw new FileNotFoundException ("File does not
not exist: " + file);
     if (!file.isFile()) {
throw new IllegalArgumentException("Should not be
be a directory: " + file);
     if (!file.canWrite()) {
throw new IllegalArgumentException("File cannot be
be written: " + file);
File tempFile = File.createTempFile("temp",
mp", "temp");
BufferedReader reader = new BufferedReader(new
(new FileReader(file));
BufferedWriter writer = new BufferedWriter(new
(new FileWriter(tempFile));
try{
while (true) {
String line = reader.readLine();
if (line == null) {
break;
line = line.replaceAll(regex,replacement);
writer.write(line);
writer.newLine();
writer.close();
reader.close();
file.delete();
tempFile.renameTo(file);
}catch (Exception e) {
     System.out.println("Exception occured :"+e);
public static void main(String[] args) {
     FileReadWrite1 f1 = new FileReadWrite1();
     File file = new File("C:\\Temp\\src1.txt");
     String regex = "us.mi.state";
     String replacement = "us.tx.state";
     f1.replace(file,regex,replacement);
}when I wrote it, I was sober and bored
now I'm drunk and amused
god
did you try and remove the magic "static" keyword ?
I wrote it static because I didn't refer to any class
member when I wrote it and that's what I felt
compelled to do, though I feel nowadays writing
anyting static suggests some design mistake
somewhere
blahblahblahblahblahs/blahblahblahblahblah/blahblahblahblahblahblah
(forgot a "blah")