What is the easiest way to generate a String of n repeated characters?

Question

Given a character c and a number n, how can I create a String that consists of n repetitions of c? Doing it manually is too cumbersome:

StringBuilder sb = ne         


        

Answer 1

Here is an O(logN) method, based on the standard binary powering algorithm:

public static String repChar(char c, int reps) {
    String adder = Character.toString(c);
    String result = "";
    while (reps > 0) {
        if (reps % 2 == 1) {
            result += adder;
        }
        adder += adder;
        reps /= 2;
    }        
    return result;
}

Negative values for reps return the empty string.