publicclassSolution {publicbooleanisPalindrome(Strings) {inti =0;intj =s.length() -1;booleanres =true;while (res) {// Iterates through string to find first char which is alphanumeric.// Done to ignore non-alphanumeric characters.// Starts from 0 to j-1.while (i <j &&isNotAlphaNumeric(s.charAt(i))) {i++;            }// Similarly from j-1 to 0.while (i <j &&isNotAlphaNumeric(s.charAt(j))) {j--;            }// Checks if i is greater than or equal to j.// The main loop only needs to loop n / 2 times hence this condition (where n is string// length).if (i >=j) {break;            }// Assigning found indices to variables.// The upperToLower function is used to convert characters, if upper case, to lower// case.// If already lower case, it'll return as it is.charleft =upperToLower(s.charAt(i));charright =upperToLower(s.charAt(j));// If both variables are not same, result becomes false, and breaks out of the loop at// next iteration.if (left !=right) {res =false;            }i++;j--;        }returnres;    }privatebooleanisNotAlphaNumeric(charc) {return (c <'a' ||c >'z') && (c <'A' ||c >'Z') && (c <'0' ||c >'9');    }privatebooleanisUpper(charc) {returnc >='A' &&c <='Z';    }privatecharupperToLower(charc) {if (isUpper(c)) {c = (char) (c +32);        }returnc;    }}