I understand that StringBuilder is faster than String when it comes to operations that require some sort of mutation. However, if I only wish to access specific characters and no other operations are required, then is there any performance difference between the charAt() methods of both?
As a trivial example, if I needed to print the alternate characters of a string, starting from the first character, is there any preferred way to do it, of the two given below?
// 1
String dummyStr = "fhweyxnqwiynfgHINYUIYIOhuiw12341dfs";
for (int i = 0; i < dummyStr.length(); i += 2) {
System.out.print(dummyStr.charAt(i));
}
// 2
StringBuilder dummySb = new StringBuilder(dummyStr);
for (int i = 0; i < dummySb.length(); i += 2) {
System.out.print(dummySb.charAt(i));
}
Additionally, are there any benefits/drawbacks of doing it this way (using a char[]) instead?
// 3
char[] dummyArr = dummyStr.toCharArray();
for (int i = 0; i < dummyArr.length; i += 2) {
System.out.print(dummyArr[i]);
}
Please note:
For this question, I am only concerned with the performance in terms of time, and not bothered about additional memory used. Also, the System.out.print() is merely a placeholder operation for the purpose of this example.
Both String and StringBuilder are backed by arrays and charAt() gets the value at the specified index.
Since String is immutable, it must make a defensive copy before returning the array. So it has some additional overhead. But imo, this would only be a problem for very large strings or repeated conversion of many strings to arrays. It all depends how how you are using it.