Isomorphic Strings

import java.util.HashMap;
import java.util.HashSet;

//****Leet code 205
public class Solution {
	public static void main (String args[]){
		Solution s1 = new Solution();
		String s = "egg";
		String t = "add";
		System.out.println(s1.isIsomorphic(s , t));
		
	}
    public boolean isIsomorphic(String s, String t) {
    	if(s.length()!= t.length()){
    		return false;
    	}
        char[] arr1 = new char[256];
        char[] arr2 = new char[256];
        for(int  i = 0; i < s.length() ; i++){
        	char ch1 = s.charAt(i);
        	char ch2 = t.charAt(i);
        	if(arr1[(int)ch1] == '\u0000' && arr2[(int)ch2] == '\u0000') {
        	arr1[(int)ch1] = t.charAt(i);
        	arr2[(int)ch2] = s.charAt(i);
        	//return true;
        	}
        	else{
        		if(arr1[(int)ch1] == t.charAt(i) && arr2[(int)ch2] == s.charAt(i)){
        		}
        	    else{
        			return false;
        		}
        	}
        }
        
        	return true;
        	}
    
    
    public boolean isIsomorphic(String s, String t){
    	HashMap<Character,Character> hm = new HashMap<Character,Character>();
    	
    	for(int i = 0; i < s.length(); i++){
    		char a = s.charAt(i);
    		char b = t.charAt(i);
    		HashSet<Character> hs = new HashSet<Character>();
    		if(hm.containsKey(a)){
    		        if(hm.get(a).equals(b)){
    		        	continue;
    		        }
    		        else{
    		        	return false;
    		        }
    		}
    		        else{
    		        	if(!hm.containsValue(b)){
    		        		hm.put(a, b);
    		        	}
    		        	else{
    		        		return false;
    		        	}
    		        }
    		
    		
    		
    		 
    		
    	
    	
    	}
    	 
		return true;
    	
    }
        	
        
       
        
    
   }