Java-用word.charAt（i + 1）替换word.charAt（i）并使word.charAt（i + 1）='A'

Question

I need to look at each word in an array, so I made a for loop with array[i] equaling String word , then I made another for loop that has an if statement that is changing word.charAt(i) with word.charAt(i+1) and changing word.charAt(i+1) = 'A' .

The objective is to 'encrypt' the word by checking if i is equal to 'A', and if it is then switching positions with i+1 .

Here is my code:

for(int i = 0; i < unchangedFileInput.length; i++) {
    String word = unchangedFileInput[i];
    for(int v = 0; v < word.length();v++) {
        if (word.charAt(v) == 'A'
                && word.charAt(v+1) != 'A' 
                && word.length() > 1) {
            char[] mywordChars = word.toCharArray();
            temp = mywordChars[v+1];
            mywordChars[v] = mywordChars[v+1];
            mywordChars[v+1] = 'A';
            word = String.valueOf(mywordChars);
        } else {
            System.out.println(word);
        }
    }
    System.out.println(word);
}

unchangedFileInput is an array that has the values of:

AVACADO
CHICKEN 
BACON 
AARDVARK

This is what the final result should look like:

AVACADO = VACADAO 
CHICKEN = UNCHANGED 
BACON = BCAON 
AARDVARK = ARADVRAK 
NAAN = NANA

Answer 1

You need to check that you don't go past the array limit first. I created a test framework,

public static void main(String[] args) {
    String[] unchangedFileInput = { "AVACADO", "CHICKEN", "BACON",
            "AARDVARK", "NAAN" };
    String[] changedFileInput = new String[unchangedFileInput.length];
    for (int i = 0; i < unchangedFileInput.length; i++) {
        changedFileInput[i] = transformName(unchangedFileInput[i]);
        System.out.printf("%s = %s%n", unchangedFileInput[i],
                changedFileInput[i]);
    }
}

And then wrapped your code in a method (and just created a new String with a StringBuilder removing the array conversions),

private static String transformName(String in) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0, len = in.length(); i < len; i++) {
        char ch = in.charAt(i);
        if (ch == 'A') {
            if (i + 1 < in.length() && in.charAt(i + 1) != 'A') {
                sb.append(in.charAt(i + 1));
                i++;
            }
        }
        sb.append(ch);
    }
    return sb.toString();
}

And I get your requested output,

AVACADO = VACADAO
CHICKEN = CHICKEN
BACON = BCAON
AARDVARK = ARADVRAK
NAAN = NANA

Answer 2

In order to achieve what you want you need to start the iteration from the end of the word to the beginning, otherwise, when you swap 'A' with the following character, you will have the 'A' again at the next iteration. If you start from the end, you will hit each 'A' only once.

Answer 3

Using this code

for(int v = 0; v < word.length();v++) {
                if (word.charAt(v) == 'A' && word.charAt(v+1)

You will get an IndexOutOfBoundsException at the end of the String.

And if you are talking about the IndexOutOfBoundsException error!!

I suggested, v < word.length() - 1;