getting java.lang.StringIndexOutOfBoundsException error [duplicate]

Answer 1

indexOf() returns -1 if the character in question isn't found in the string. So, you need to build in some contingency for that happening. When the character isn't found in "from", what do you want the code to do?

Answer 2

This is your assignment inside your for loop: -

char c = to.charAt(from.indexOf(line.charAt(i)));

Here, in indexOf returns -1 when the char is not found in from string, and then it will throw an StringIndexOutOfBoundsException.

You can add a check before fetching the character: -

int index = from.indexOf(line.charAt(i));

if (index >= 0) {
    char c = to.charAt(index);
    outPutText += c;
}

or: -

char ch = line.charAt(i);

if (from.contains(ch)) {
    char c = to.charAt(from.indexOf(ch));
    outPutText += c;
}