Java list index out of range
In java, what is the best way to switch characters in a string while keeping the rest of the characters in their original spot. My real concern is if there's a way to deal with this index out of range error other than the following:
Let's say you want to switch the letter r with the capital E in "stringExample".
you can chunk this into "st" + "r" + "ing" + "E" + "xample"
---------------------------->(0,i)--(i,i+1)--(i+1,k)--(k,k+1)---(k+1)
then to switch "r" & "E": "st" + "E" + "ing" + "r" + "xample"
----------------------------->(0,i)--(k,k+1)--(i+1,k)--(i,i+1)---(k+1)
The only problem is if k is the last index then you need to write an if statement to catch this exception. Other than doing what I suggested before, is there a better way of switching these letters?
If you're looking to just replace characters in a string, you're probably best off rebuilding your string entirely using String.substring. For your example, you'd simply need to use temporary variables to hold the letters you want to swap. For example:
String swapLetters(String str, int firstIndex, int secondIndex) {
if (firstIndex < 0 || firstIndex >= str.length()) {
throw new IndexOutOfBoundsException("firstIndex '" + firstIndex + "' is out of bounds.");
} else if (secondIndex < 0 || secondIndex >= str.length()) {
throw new IndexOutOfBoundsException("secondIndex '" + secondIndex + "' is out of bounds.");
} else if (firstIndex >= secondIndex) {
throw new IndexOutOfBoundsException("firstIndex isn't before secondIndex");
}
StringBuilder newString = new StringBuilder(str.substring(0, firstIndex));
newString.append(str.charAt(secondIndex)).append(str.substring(firstIndex + 1, secondIndex))
.append(str.charAt(firstIndex)).append(str.substring(secondIndex + 1));
return newString.toString();
}
Here, even if it's the last letter the substring will just return an empty string and it'll be fine.
System.out.println("stringExample becomes " + swapLetters("stringExample", 2, 12)); //--> stringExample becomes steingExamplr
System.out.println("stringExample becomes " + swapLetters("stringExample", 2, 6)); //--> stringExample becomes stEingrxample
If you want to just replace the first instance of each letter given letters, you'd use indexOf('r') instead of charAt(2), for example.