leetcode | Isomorphic Strings

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to get t.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.

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

Given "foo", "bar", return false.

Given "paper", "title", return true.

public class Solution {
    public boolean isIsomorphic(String s, String t) {
        Map<Character,Character> map = new HashMap<Character,Character>();
            for(int i=0;i<s.length();i++)
            {
                if(!map.containsKey(s.charAt(i)))
                {
                    if(map.containsValue(t.charAt(i)))
                        return false;
                    map.put(s.charAt(i),t.charAt(i));
                }
                else
                {
                    if(!map.get(s.charAt(i)).equals(t.charAt(i)))
                        return false;
                }
            }
            return true;
    }
}