ReplaceText.java

import java.io.*;       // for file handling
import java.util.Scanner;   // for user input

public class ReplaceText {

    /**
    *   Program:    ReplaceText.java
    *   Creator:    Chris Clarke
    *   Created:    18.10.2012
    *   Purpose:    Open text file, replace <oldtext> with <newText>, save.
    */

    public static void main(String[] args) {
        String oldText, newText;
        String allText;
        String fileName, backupName;
        String backup;

        Scanner scan = new Scanner(System.in);
        System.out.print("Enter filename, including path: ");
        fileName = scan.nextLine();

        if (fileName.equals("")) {
            System.out.println("No file!");
            return;
        } // end if

        System.out.print("Enter text to be replaced: ");
        oldText = scan.nextLine();

        if (oldText.equals("")) {
            System.out.println("No text entered!");
            return;
        } // end if

        System.out.print("Enter replacement text: ");
        newText = scan.nextLine();

        System.out.println();

        allText = readFromFile(fileName);

        System.out.print("Make backup (y/n)? ");
        backup = scan.nextLine();
        if (backup.toLowerCase().startsWith("y")) {
            System.out.print("Enter backup filename, including path: ");
            backupName = scan.nextLine();
            writeToFile(backupName, allText);
        } // end if

        allText = allText.replaceAll(oldText, newText);
        writeToFile(fileName, allText);

    } // end main

    private static String readFromFile(String fileName) {
        String text = "";
        try {
            // Create the readers.
            FileReader fr = new FileReader(fileName);
            LineNumberReader lnr = new LineNumberReader(fr);

            // Read line by line
            String s = " "; // Anything but null.
            while (s != null) {
                s = lnr.readLine();
                if (s == null) break;
                System.out.println(s); // option to display text
                text += s+"\r\n"; // add line of text plus newline
            } // end while
            // Close the readers.
            lnr.close();
            fr.close();
        }
        catch (IOException x) {
            System.out.println("Trouble reading! " + x.getMessage());
        } // end try...catch

        return text;

    } // end readFromFile

    private static void writeToFile(String fileName, String text) {
        if (text.equals("")) return;
        try {
            // Create the writer.
            BufferedWriter fw = new BufferedWriter(new FileWriter(fileName));
            for (int i=0; i<text.length(); i++) {
                System.out.print(text.charAt(i)); // option to display text
                fw.write(text.charAt(i));
            } // end for
            fw.close();
            System.out.println("File saved.");
        }
        catch (IOException x) {
            System.out.println("Trouble writing! " + x.getMessage());
        } // end try...catch
    } // end writeToFile
} // end class