替换字符串中的char值（Java）

Question

In my assignment I need to get this output:

Enter a word: house
What letter do you want to replace?: e
With what letter do you wish to replace it? w
The new word is housw.

_____________________________________________.

I got the program to work with this code, but now I need to set while loops. Here is my current code.

String word = ""; Scanner keyboard = new Scanner(System.in);

    System.out.print("Enter a word: " + word);
    word = keyboard.nextLine();

    String readChar = null;
    System.out.print("What letter do you want to replace?: ");
    readChar = keyboard.next();

    String changeChar;
    System.out.print("With what letter do you wish to replace it? ");
    changeChar = keyboard.next();

    keyboard.close();
    System.out.println(word.replaceAll(readChar, changeChar));

    System.out.println();

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I need to now make my program output this:

Enter a word: house
What letter do you want to replace?: a
There is no a in house.
What letter do you want to replace?: b
There is no a in house.
What letter do you want to replace?: e
With what letter do you wish to replace it? w
The new word is housw.

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How would my while loop look to portray this output?

Answer 1

After you read the word and the character you want to replace (plus the character you want to replace it with) you can use replace method from the String class.

Here is an example usage (adapt the variable names to your code)

word = word.replace(letterToReplace, replacementLetter);

So for example

String word = "aba";
word = word.replace('a', 'c');
System.out.println(word); // Prints out 'cbc'

Also here is an obligatory link to the JavaDoc for the replace method:

http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#replace%28char,%20char%29

Answer 2

I hope you don't mind hard interpretation,Below is the example you can follow the same.

 String a = "HelloBrother How are you!";
 String r = a.replace("HelloBrother","Brother");

 print.i(r);

Answer 3

If you want to replace all of the letters, you can do it like this (working code):

public static void main(String[] args) {

    String word = "";
    Scanner keyboard = new Scanner(System.in);

    System.out.print("Enter a word: " + word);
    word = keyboard.nextLine();

    String readChar = null;
    System.out.print("What letter do you want to replace?: ");
    readChar = keyboard.next();

    String changeChar;
    System.out.print("With what letter do you wish to replace it? ");
    changeChar = keyboard.next();

    keyboard.close();
    System.out.println(word.replace(readChar, changeChar));
}

Answer 4

Okay this is one possible way to implement the edited second part of the question:

public static void main(String[] args) {

    String word = "";
    Scanner keyboard = new Scanner(System.in);

    System.out.print("Enter a word: " + word);
    word = keyboard.nextLine();

    boolean done = false;
    do{
        String readChar = null;
        System.out.print("What letter do you want to replace?: ");
        readChar = keyboard.next();

        if(word.contains(readChar)){

            String changeChar;
            System.out.print("With what letter do you wish to replace it? ");
            changeChar = keyboard.next();

            done = true;
            keyboard.close();
            System.out.println(word.replace(readChar, changeChar));
        }
    }
    while(!done);
}

Answer 5

This illustrates what you need to do.

import java.util.Scanner;
public class WordScrambler{

    public static void main(String[] args) {

    Scanner keyboard = new Scanner(System.in);

    System.out.print("Enter a word: ");
    String word = keyboard.nextLine();

    System.out.print("What letter do you want to replace?: ");
    char letter = keyboard.next().charAt(0);

    StringBuffer out = new StringBuffer(word);
    System.out.print("With what letter do you wish to replace it? ");
    char changeChar = keyboard.next().charAt(0);

    for (int i=0; i<word.length(); ++i) 
        if(word.charAt(i) == changeChar)
            out.setCharAt(i, changeChar);

    System.out.println("The new word is "+out);
    }
}