Question

I am trying to go through an array of characters and replace that character in the string with the parallel character in the other array.

private String replace(String input)
{
    char[] first = {'a','e','o','s'};
    char[] second = {'@','3','0','$'};
    String myCopy = input.toLowerCase();


    for(int y = 0; y < first.length; y++)
    {
        myCopy.replace(first[y],second[y]);
    }


    return myCopy;
}

Here’s and example of what I get:

Enter a string: as the dog runs here
Output: as the dog runs here

It always outputs the same string with no replacements.

I also tried using:

myCopy.replace('a','@');

and

myCopy.replace("a","@");

and the replaceAll method.

Any suggestions?

Answer 1

Strings are immutable in Java. replace() doesn’t change the string you call it on – it returns a new string with the changes. So you want:

myCopy = myCopy.replace(first[y], second[y]);

(The same is true for all the methods on String which “appear” to be changing it, as it’s immutable.)