Inserting text in middle using RandomAccessFile removes some text after that

Question

My Sample Code

    String line = null;
    RandomAccessFile file = new RandomAccessFile(\"D:/mahtew.txt\", \"rw\");
    System.out.println(file.getFilePointe         


        

Answer 1

Understand that when you write with a RAF, you over-write data which was previously held at the file pointer location. If you want to insert text into a file, I suggest that you not use a RAF but rather simply read the text of the file into a String or ArrayList or StringBuilder, using a File held by a FileReader wrapped in a BufferedReader or a File wrapped in a Scanner, alter the Strings or StringBuilder held in memory, and then write the altered data to the new file using a FileWriter wrapped in a PrintWriter.

e.g.,

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class AppendLine {
   private static final String FILE_PATH = "src/tetris/mahtew.txt";
   private static final String MARKER_LINE = "Text to be appended with";
   private static final String TEXT_TO_ADD = "new text has been appended";

   public static void main(String[] args) {
      List fileLines = new ArrayList();
      Scanner scanner = null;
      try {
         scanner = new Scanner(new File(FILE_PATH));
         while (scanner.hasNextLine()) {
            String line = scanner.nextLine();
            fileLines.add(line);
            if (line.trim().equalsIgnoreCase(MARKER_LINE)) {
               fileLines.add(TEXT_TO_ADD);
            }
         }

      } catch (FileNotFoundException e) {
         e.printStackTrace();
      } finally {
         if (scanner != null) {
            scanner.close();
         }
      }

      PrintWriter pw = null;
      try {
         pw = new PrintWriter(new File(FILE_PATH));
         for (String line : fileLines) {
            pw.println(line);
         }
      } catch (FileNotFoundException e) {
         e.printStackTrace();
      } finally {
         if (pw != null) {
            pw.close();
         }
      }
   }
}