java - How to decrypt this String -

given following string:

string s = "qba'g sbetrg gb qevax lbhe binygvar"; 

my desired output is:

don't forget drink ovaltine

my code:

public static string decrpyt(string s){      string ans = "";      (int = 0; i<s.length(); i++) {         int x = s.charat(i);          if (x <= 105) {             char c = ((char) (x + 13));              ans += c;         } else {              char c = ((char) (x - 13));              ans += c;         }     }     return ans;   } 

it returns:

don4t-forget-to-drink-_our-ovaltine

what need desired output?

you changing characters, not letters, has been mentioned in comment. consider range of characters letters need modify. declare x char don't have consider actual numeric ranges.

a-m => n-z   action: += 13 a-m => n-z   action: += 13 n-z => a-m   action: -= 13 n-z => a-m   action: -= 13 (all others) action: no change 

this can expressed in 3 cases:

if ((x >= 'a' && x <= 'm') || (x >= 'a' && x <= 'm')) {     // add 13 } else if ((x >= 'n' && x <= 'z') || (x >= 'n' && x <= 'z')){     // subtract 13 } else {     // use }