Shift all character codes within a string to a constant value

Question

Using the Java .

This code works:

for (char c : sourceString.toCharArray()) {
    destString += (char) (c + shiftValue);
}
System.out.println(destString);

Is there a better / faster (optimized) way?

Answer 1

Well, I would avoid using re-concatenation of strings , for starters. This is a very well known performance issue.

In this case, you know the exact length with which you need to start, so you don't even need to StringBuilder- a char[]in order:

char[] result = new char[srcString.length()];
for (int i = 0; i < result.length; i++) {
    result[i] = (char) (srcString.charAt(i) + shiftValue);
}
String destString = new String(result);

( toCharArray, , , . , . , O (N), O (N ²)).

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Answer 2

. charAt(i) .

char[] result = srcString.toCharArray();
for (int i = 0; i < result.length; i++) {
    result[i] += shiftValue;
}
String destString = new String(result);

Answer 3

, :

StringBuilder destString = new StringBuilder();
for (char c : srcString.toCharArray()) {
    destString.appned((char) (c + shiftValue));
}
System.out.println(destString.toString());