*****The following JAVA code does the following: (NOT WHAT NEEDS TO BE ANSWERED)

Question

*****The following JAVA code does the following: (NOT WHAT NEEDS TO BE ANSWERED)

Create a file containing 100 randomly generated upper case characters.

Display the contents of the file in 10 rows of 10 characters.

Open the file for random access.

Prompt the user for a position to modify in the displayed characters, and the character to write to that position.

Display the modified contents.

Sample run of original program

*** What I need is for this code to be expanded to replace every occurence of a single letter, for example E. Every E will be replaced with what the user specifies. The location of every e will also be outputted. So the two things I need expanded are

1) Change every occurance of a single letter (example E)

2) output the location in a similar manner as original program asked user to specify which letter is to be changed (example E's at 2,3,4, and 5)

JAVA CODE************

Explanation / Answer

import java.io.*;
import java.util.Scanner;

class fileTest3
{
    public static void main(String[] args)throws IOException
   {
       char randChar;
      
       if(args.length != 1)
       {
           System.out.println("No path\filename entered");
           System.exit(1);
       }
       String theFile = args[0];

       try( DataOutputStream output = new DataOutputStream(new FileOutputStream(theFile));
       DataInputStream input = new DataInputStream(new FileInputStream(theFile)); )
       {

       //begin try with resources // write 100 random upper case characters to file           
           for(int i = 0; i < 100; i++)
           {
               randChar = (char)('A' + Math.random() * ('Z' - 'A' + 1));               
               output.writeChar(randChar);
           } // display file contents
           for(int j = 0; j < 10; j++)
           {
               for(int i = 0; i < 10; i++)
               {
                   System.out.print(input.readChar() + " ");
               }
               System.out.println();
           }
       }//end try with resources
      
       //Random access -----------------------------------                   
      
       Scanner input = new Scanner(System.in);

       RandomAccessFile raf = new RandomAccessFile(theFile, "rw");                   
       System.out.println("Current length of the file is: " +raf.length());           
       System.out.print("Replace character number: ");
       while(!raf.EOF)
       {
       int position = input.nextInt();
       System.out.print("with the character: ");
       String theChar = input.next();
       raf.seek((position-1)*2);
       raf.writeChars(theChar);
       }
       raf.close();

       try( DataInputStream input2 = new DataInputStream(new FileInputStream(theFile));
       )
       {
       //begin try with resources
       // display file contents
       for(int j = 0; j < 10; j++)
       {
           for(int i = 0; i < 10; i++)
           {
               System.out.print(input2.readChar() + " ");
           }
           System.out.println();
       }
   }
   //end try with resources
   }
// end main
}//end class

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