Leetcode OJ 205 Isomorphic Strings

Given strings s andt, determine if they are isomorphic.

The strings is isomorphic if the characters in s can is replaced to get t.

All occurrences of a character must is replaced with another character while preserving the order of characters. No, characters may map to the same character and a character may map to itself.

For example,
Given "egg" , "add" return True.

Given "foo" , "bar" return FALSE.

Given "paper" , "title" return True.

Note:
Assume both s and T have the same length.

Test instructions: Determine two strings of the same string, that is, the characters in s are replaced with the corresponding characters in T, can guarantee that the different characters in s to replace the different characters in T, can be imagined as an encryption process, using some kind of mapping, the s to encrypt t

public class Solution {public    Boolean isisomorphic (string s, String t) {        //use map to save the mapping relationship        Map<character, character> map = new hashmap<character,character> ();        for (int i = 0; i < s.length (); i + +) {            char key = S.charat (i);            Char value = T.charat (i);            if (Map.containskey (key)) {                if (value! = Map.get (key)) {//exists a key->x mapping and x! = value                    return false;                }            } else if (Map.containsvalue (value)) {                return false;//already has a x->value mapping, but x! = key            }else{//does not exist key-> x mapping and mapping of X->value                map.put (key,value);            }        }        return true;    }}

Search, feel other people's algorithm is similar to mine, did not find a very efficient algorithm, why my running time so slow

Leetcode OJ 205 Isomorphic Strings