Thread: String in java

Greetings


Consider in a Document if a String " Hello" is Encoded and stored as "XYZAB"

I want to search the text on document for a word "Hello" and Replace the word with "HelloWorld"

The Program will encrypt the word "Hello" and Search the file then return the encrypted code as "XYZAB" Found

Now i have to replace the word "Hello" with "HelloWorld" in encrypted form so that the Letter "XYZABEFGHI" is replace in the place of Hello

where "World" is encoded as "EFGHI"

Now the Problem is If there is more number of occurrence of the word "Helloworld" exist in the file... How can i Replace only one particular occurrence What

can be done to select the particular occurrence.



Please Do Kindly Help me in sorting out the problem


i have attached my java program for Encryption along with this mail for your ease of use.


I Got struct here and cannot proceed further so please please kindly provide me a solution to proceed further...

OUTPUT

Enter the key :
key
PlainText : RAGU XYZ RAGU
CipherText : BEEE VID BEEE



package javaapplication7;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.util.Scanner;

/**
*
* @author Ragunath Gunasekaran
*/
public class JavaApplication7 {

/**
* @param args the command line arguments
*/
public static void main(String[] args) throws Exception

{

Scanner in = new Scanner(System.in);
Scanner file = new Scanner(new File("C:/Users/Ragunath Gunasekaran/Desktop/result.txt"));

System.out.println("Enter the key : ");


// TIMER START

long startTime = System.currentTimeMillis();

long total = 0;
for (int i = 0; i < 10000000; i++)
{
total += i;
}



String key = in.nextLine().toUpperCase();

String input="";
while(file.hasNext())
input+=file.nextLine().toUpperCase();

System.out.println("PlainText : "+input);

String cipher="";
for(int i=0;i<input.length();i++)
{
char c = input.charAt(i);
if(c>='A'&&c<='Z')
{
c=(char)(c+(key.charAt(i%key.length())-'A'));
// if(c<'A')c+=26;
if(c>'Z')c-=26;
}
cipher+=c;
}

System.out.println("CipherText : "+cipher);

FileWriter fstream1 = new FileWriter("C:/Users/Ragunath Gunasekaran/Desktop/final.txt");
BufferedWriter out = new BufferedWriter(fstream1);
// cipher = br.readLine();
out.write(cipher);
out.close();

String plaintext1 = "";
for(int i=0;i<cipher.length();i++)

{
char c = cipher.charAt(i);
if(c>='A'&&c<='Z')
{
c=(char)(c-(key.charAt(i%key.length())-'A'));
if(c<'A')c+=26;
// if(c>'Z')c-=26;
}
plaintext1 +=c;
}

// System.out.println("PlainText : "+plaintext1);

// TIMER Run time & Print
long stopTime = System.currentTimeMillis();
long elapsedTime = stopTime - startTime;
System.out.println("\n Runtime of the Ecryption Program "+elapsedTime);
//TIME FINISH -Result Finish

}


}