Week 8 - Loop Review Example

Replace.java

/**
  * Replace: This program reads in lines of input until the user enters
  * the word 'stop.'  For each line of input, the program should print out
  * the line after substituting each occurence of the letter 'e' (lower
  * case only) with an A, then a B, then a C, then a D, etc. You can assume
  * that each input line has no more than 26 occurences of the letter 'e'.
 */

import java.io.*;
public class Replace {
    public static void main (String[] args) throws IOException {
        BufferedReader in = new BufferedReader (new
                                InputStreamReader (System.in));

        // Prompt user, and read in first line of text
        System.out.println ("Enter lines of text.  Use 'stop' to end.");
        String line = in.readLine();

        // Repeat until user enters 'stop'
        while (!line.equals("stop")) {
            String result = "";    // Stores the output line
            int capCounter = 0;    // Keeps track of how far we are away
                                  //   from capital 'A' in the ASCII table.

            // Loop to count through each character in the original line.
            for (int i=0; i<line.length(); i++) {

                // The character was an 'e', so replace it the ASCII value
                // of 'A' plus our 'capCounter' as described above.  Cast
                // the result back to character.
                if (line.charAt(i) == 'e') {
                    result += (char)('A' + capCounter);
                    capCounter++;
                } else {
                    result += line.charAt(i);
                }
            }

            // Print out the new line.
            System.out.println (result);

            // Read next line of text.
            line = in.readLine();
        }
    }
}

Sample program run (input boldfaced)

Enter lines of text.  Use 'stop' to end.
kjsweaeasefasefaesfsefawfasefawefsfase
kjswAaBasCfasDfaEsfsFfawfasGfawHfsfasI
esjaslejafslekjfalsejflaskejalskejfalskelfkasealeee
AsjaslBjafslCkjfalsDjflaskEjalskFjfalskGlfkasHalIJK
awsekarjselakfjealksjelfaeseeeeeeeeeafasefasefasefawefseefase
awsAkarjsBlakfjCalksjDlfaEsFGHIJKLMNafasOfasPfasQfawRfsSTfasU
stop