How Can I replace line in text file

Question

I have a text file like following format
1
bvhhk
g1
2
bvgjvh
g1
3
mmm,mvb
g2
I want to replace 2 nd line to " prasad" and after replacing it should be following format
1
prasad
g1
2
bvgjvh
g1
3
mmm,mvb
g2
I try above change using following code segment and it is not work.
static void modifyEmployeeDetails(String file_name){
try{
     InputStreamReader reader= new InputStreamReader(System.in);
     BufferedReader buff=new BufferedReader(reader);
     FileReader read=new FileReader(file_name);
     BufferedReader buffer=new BufferedReader(read);
     FileWriter w=new FileWriter(file_name,true);
     PrintWriter write = new PrintWriter(w);
     System.out.print("Employee No : ");
     String No=buff.readLine();
boolean eof = false;
while (!eof) {
String tep=buffer.readLine();
if(tep.equals(No)){
eof = true;
System.out.print("Name : ");
temp=buff.readLine();
System.out.println("No");
write.println(temp);
System.out.print("Group No : ");
temp=buff.readLine();
write.println(temp);
}catch(Exception e){
System.out.println(e);
Please correct If it is wrong and help me as soon as possible
Thank you...............

Answer 1

hi,
I have a different approach of the solution to your problem.
suppose you have entries in your file without any extra line feed between each two entries.
the following program entirely reads your data into a bean list, changes a specific bean attribute and writes it to your data source.
(you should adapt it to your needs)
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class FileReplace {
     public List<MyBean> readFile(BufferedReader in) throws IOException{
          String line;
          List<MyBean> beanList = new ArrayList<MyBean>();
          MyBean bean = null;
          int i=0;
          while((line=in.readLine())!=null){
               if(line.trim().equals("***")){
                    beanList.add(bean);
                    i = 0;
               }else{
                    switch (i) {
                    case 0:
                         bean = new MyBean();
                         bean.setAttribute1(line);
                         i++;
                         break;
                    case 1:
                         bean.setAttribute2(line);
                         i++;
                         break;
                    case 2:
                         bean.setAttribute3(line);
                         i++;
                         break;
                    default:
                         break;
          return beanList;
     public void writeToFile(List<MyBean> beanList, String outputFilePath) throws IOException{
          FileWriter out = new FileWriter(outputFilePath);
          for (int i = 0; i < beanList.size(); i++) {
               out.write(beanList.get(i).toString());
          out.flush();
          out.close();
     public void test(){
          //BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
          String filePath = "D:/file.txt";
          try {
               BufferedReader in = new BufferedReader(new FileReader(filePath));
               //read data
               List<MyBean> beanList = readFile(in);
               // edit a bean attribute
               beanList.get(0).setAttribute2("prasad");
               //write beans back to file
               writeToFile(beanList, filePath);
          } catch (FileNotFoundException e) {
               e.printStackTrace(); //handle appropriately this exception
          } catch (IOException e) {
               e.printStackTrace();//handle appropriately this exception
          }catch (Exception e) {
               e.printStackTrace();//handle appropriately this exception
     class MyBean{
          String attribute1;
          String attribute2;
          String attribute3;
          public final static int ATTRS_NUMBER = 3;
          public String getAttribute1() {
               return attribute1;
          public void setAttribute1(String attribute1) {
               this.attribute1 = attribute1;
          public String getAttribute2() {
               return attribute2;
          public void setAttribute2(String attribute2) {
               this.attribute2 = attribute2;
          public String getAttribute3() {
               return attribute3;
          public void setAttribute3(String attribute3) {
               this.attribute3 = attribute3;
          @Override
          public String toString() {
               return attribute1+"\n"+attribute2+"\n"+attribute3+"\n***\n";
     public static void main(String[] args) {
          FileReplace instance = new FileReplace();
          instance.test();
}hope it helps