Is there any method or idea that can select characters from a string at indices which are multiple of given 'n' to get the result string?

Question

If I have this string

String str="characters";

the result would like following

result="caatr";

what I have done is selecting char by char from the given string until we get the result. The chars are selected at indices which are multiples of given n. Example: if n=2, the relevant indices to be selected are 0, 2, 4 ... and for n = 3, the indices are 0, 3, 6...

I have solved it in two ways and are almost the same but is there any other ways?

char[] arr = str.toCharArray();
String s="";
for(int i=0;i<str.length();i=i+n)
    s=s+arr[i]+"";

the other one is

String result = "";
for (int i=0; i<str.length(); i = i + n) 
    result = result + str.charAt(i);

Answer 1

public static void main(String args[]) {
    System.out.println(getResultOf("characters"));
}

private static String getResultOf(String input) {
    boolean skip = false;
    StringBuilder sb = new StringBuilder();
    for (char ch : input.toCharArray()) {
        if (!skip) {
            sb.append(ch);
        }
        skip = !skip;
    }
    return sb.toString();
}