Speed/efficiency tradeoff with String.length() and string.toCharArray().length
arrays, char, java, performance, string
Solution
Since you have both objects already, the time complexity is the same: it's O(1), because both `java.lang.String` and Java arrays store their length for direct retrieval.
However, you can improve upon the timing of your method by using `getChars` method of the string to avoid copying the characters past the end of the substring that you need:
int maxLength = 100;
int effectiveLength = Math.min(maxLength, str.length());
char[] strArray = new char[effectiveLength];
str.getChars(0, effectiveLength, strArray, 0);
If it happens that your algorithm can stop processing before reaching the end of the string, this approach would let you avoid allocating the extra memory and copying the characters into it.
Problem
I have a method that accepts a `String` parameter. I need to convert my `String` to a `char[]` for processing. However, if my String is greater than a certain length, I can stop processing my method logic. ``` public void doSomething(String str) { char[] strArray = str.toCharArray(); // do something } ``` I know that in terms of space efficiency, I should just check `str.length()` before creating my `char[]`. However, this got me thinking. In terms of time complexity, which is more efficient assuming I needed the `char[]` anyways? Assuming I already have two objects `String` and `char[]`, which is faster/more efficient? `str.length()` `strArray.length`