Simple gg encoder fixed length character

    private static String simpleEncoder(String message){
        StringBuilder keySet=new StringBuilder();
        StringBuilder key=new StringBuilder();
        StringBuilder encodedMessage=new StringBuilder();

        for(int i=0, n=message.length();i<n;i++){
            char c=message.charAt(i);

            if(c>='A'&&c<='Z'||c>='a'&&c<='z'){
                StringBuilder gg=new StringBuilder(Integer.toBinaryString(c-65));
                while(gg.length()<6){
                    gg.insert(0,'g');
                }
                for(int j=0, m=gg.length();j<m;j++){
                    char d=gg.charAt(j);
                    if(d=='0'){
                        gg.setCharAt(j,'g');
                    }
                    if(d=='1'){
                        gg.setCharAt(j,'G');
                    }
                }
                if(keySet.indexOf(new Character(c).toString())<0){
                    keySet.append(c);
                    key.append(c).append('\u0020').append(gg).append('\u0020');
                }
                encodedMessage.append(gg);
            }
            else{
                encodedMessage.append(c);
            }
        }
        return key.append("\n").append(encodedMessage).toString();
    }