( Replace text ) Listing 12.16, ReplaceText.java, gives a program that replaces

Question

(Replace text) Listing 12.16, ReplaceText.java, gives a program that replaces text in a source file and saves the change into a new file. Revise the program to save the change into the original file. For example, invoking

My file looks like this

~~~~~~

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;

public class WriteRandomNumbers{
   public static void main(String[] args) {
       try {

          
           File file = new File("Exercise12.15.txt");

           // if file does'nt exists, then create it
           if (!file.exists()) {
               file.createNewFile();
           }

           FileWriter fw = new FileWriter(file.getAbsoluteFile());
           BufferedWriter bw = new BufferedWriter(fw);
          
           Random rand = new Random();
           int max=100;
           int min=1;
          
           System.out.println("Generating Random numbers");
           for(int i=1;i<=100;i++) {
              
               int randomNum = rand.nextInt((max - min) + 1) + min;
               bw.write(randomNum+" ");
                  
           }
           System.out.println("Writing Random numbers to Exercise12.15.txt is completed");
          
           bw.close();
          
          
           //Read data back from file
           System.out.println("Reading data back from file:");
           String sCurrentLine;
             
           BufferedReader br = new BufferedReader(new FileReader("Exercise12.15.txt"));
          
           int data[] = new int[100];
           int j=0;
           while ((sCurrentLine = br.readLine()) != null) {
               String lineData[] = sCurrentLine.split(" ");
               for(int i=0;i<lineData.length;i++) {
                   data[j] = Integer.parseInt(lineData[i]);
                   j++;
               }
                  
           }
           br.close();
          
           //Sort data in increasing order using bubble sort
           for(int i=0;i<j-1;i++) {
               for(int k=i+1;k<j;k++) {
                   if(data[i]>data[k]) {
                       int temp = data[i];
                       data[i] = data[k];
                       data[k] = temp;
                   }
               }
           }
          
           //Finally print data
           System.out.println("File data in increasing order");
           for(int i=0;i<j;i++) {
              
               System.out.print(data[i]+" ");
               if((i+1)%5==0) {
                   System.out.print(" ");
               }
           }
       } catch (IOException e) {
           e.printStackTrace();
       }
   }
}

Explanation / Answer

import java.io.*;

import java.util.*;

//import java.util.regex;

public class Replacement {

    List<String> lines = new ArrayList<String>();

    public void replace(){

    try {

        FileReader fr = new FileReader("C:\Users\kajal\Desktop\all text files\profile.txt");

        BufferedReader br = new BufferedReader(fr);

        FileWriter fw = new FileWriter("C:\Users\kajal\Desktop\all text files\profile.txt");

        BufferedWriter bw = new BufferedWriter(fw);

        String line = null;

        while((line=br.readLine()) != null) {

        line.replaceAll("javascript", "perl script"); //I also tried , line=line.replaceAll("javascript", "perl script");

        bw.write(line);

            }

        }

    catch(IOException ioe){}

    }

        public static void main(String [] args) {

        Replacement r = new Replacement();

        r.replace();

    }

}

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