Character can be obtained at one particular index, within a string, by charAt() accessor methodís invoking. First character index is 0 however last character index is length()-1. This given example shows the code which obtains the character, at index 9 present in string.
String anotherPalindrome = "Niagara. O roar again!";
char aChar = anotherPalindrome.charAt(9);
Indices start with 0 therefore the characters which are present at the index 9 are 'O'.