Creating a Variable Using a Loop

Question

I'm writing a program that's supposed to replace all of the instances of a single letter with another letter. I have some restrictions on the code though, I'm only allowed to use the String methods .length, .substring, .indexOf, and .equals. I can concatenate things using + instead of .concat.

My problem right now is, when I'm printing my results to the program, the answer has to be contained in a variable. I was previously using this code before I realized this:

    if (userCommand.equalsIgnoreCase("replace all")) {
        System.out.println("Enter the character to replace");
        String replace = keyboard.nextLine();
        System.out.println("Enter the new character");
        String replaceWith = keyboard.nextLine();

        int count = 0;

        System.out.print("The new string is: ");
        while (lastCharacter >= 0) {
            char nextCharacter = userString.charAt(count);
            count++;
            String nextCharacterString = nextCharacter + "";
            if (nextCharacterString.equals(replace)) {
                nextCharacterString += replaceWith;
            }
            System.out.print(nextCharacterString);

            lastCharacter--;
        }
        System.out.println("");
    }

As you can see, this prints each character to the console one by one, instead of as a variable that can be manipulated later. The code I'm using right now (it is nowhere near working) is:

    if (userCommand.equalsIgnoreCase("replace all")) {
        System.out.println("Enter the character to replace");
        String replaceString = keyboard.nextLine();
        char replace = replaceString.charAt(0);
        System.out.println("Enter the new character");
        String replaceWithString = keyboard.nextLine();
        char replaceWith = replaceWithString.charAt(0);
        String allLetters = "";
        int count = 0;
        int indexOfReplacement = 0;

        for (int i = 0; i < length; i++) {
            char nextCharacter = userString.charAt(count);
            count++;

            if (replace == nextCharacter) {
                indexOfReplacement = count;
                nextCharacter = replaceWith;
            }
        }
        String sub1 = userString.substring(0, indexOfReplacement);
        System.out.println(sub1);
    }

Any help would be very much appreciated.

So what is your problem? If you just want to save to a variable instead of printing, just replace System.out.print(...) with myVariable = myVariable + ... with myVariable being a String — SourceOverflow
– SourceOverflow, Commented Oct 5, 2017 at 21:35

Steampunkery · Accepted Answer · 2017-10-05 22:23:21Z

Here is a small snippet I wrote up. I made some assumptions about the contents of variables to make it be able to run, but it works, replacing all instances of replace with replaceWith:

String your_string = ""; // Variable to copy the new string into
String userString = "this_string"; // String to do replacement on
int lastCharacter = userString.length() - 1; // Length of inputted string
String replace = "g"; // Thing to replace
String replaceWith = "d"; // Thing to replace with
int count = 0; // Index of character in string
while(lastCharacter >= 0) {
    char nextCharacter = userString.charAt(count);
    String nextCharacterString = nextCharacter + "";
    if (nextCharacterString.equals(replace)) {
        nextCharacterString = replaceWith; // I changed += to = because we want to replace, not add
    }
    System.out.print(nextCharacterString);
    your_string = your_string + nextCharacterString; // This is where we add the correct character to the string
    lastCharacter--;
    count++;
}

MLPJ · Accepted Answer · 2017-10-05 21:44:11Z

0

you can use an arraylist

ArrayList<String> list=new ArrayList<String>();
while(lastCharacter >= 0)
              {
                  char nextCharacter = userString.charAt(count);
                  count ++;
                  String nextCharacterString = nextCharacter + "";
                  if (nextCharacterString.equals(replace))
                  {
                      nextCharacterString += replaceWith;  
                  }
                  System.out.print(nextCharacterString);
                  list.add(nextCharacterString);
                  lastCharacter --;
              }

so you can manipulate it later

answered Oct 5, 2017 at 21:44

MLPJ

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2 Comments

Steampunkery Over a year ago

Why add them to an ArrayList when we have an entire library devoted to strings?

MLPJ Over a year ago

Jake stated that he needs to manipulate the strings later. So adding them to the list would do that. There could be many solutions though

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