/* Given a string, return a string where for every char in the original, * there are two chars. */ public String doubleChar(String str) { char[] arr = new char[2 * str.length()]; int count = 0; for(int i = 0; i < str.length(); i++) { arr[count] = str.charAt(i); count++; arr[count] = str.charAt(i); count++; } return new String(arr); }