Помогите понять, в чем ошибка?

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String url = reader.readLine();
        //напишите тут ваш код
        url = url.substring(url.indexOf("?") + 1);
        StringBuilder x = new StringBuilder();
        int i = 0;
        String tmp = url;
        String tmp2 = url;
        double answer = 0;
        String result = null;

        String string = "";
        for(int z = 0; z < tmp2.length(); z++){

            int ind = 0;
            if(String.valueOf(tmp2.charAt(z)).equals("=")){
                string = tmp2.substring(0,z);
                tmp2 = tmp2.substring(z);

            }
            if(String.valueOf(tmp2.charAt(z)).equals("&")){
                tmp2 = tmp2.substring(z);
                break;
            }
        }
        tmp2 = tmp2.replaceAll("&"," ");
        for(int j = 0; j < tmp2.length(); j++){
            if(String.valueOf(tmp2.charAt(j)).equals("=")){
                tmp2 = tmp2.substring(0,j);
                result = string + tmp2;


            }
        }
        while (true){
            try {

                if(String.valueOf(tmp.charAt(i)).equals("=")){
                    tmp = tmp.substring(i);
                }


                if(String.valueOf(tmp.charAt(i)).equals("&")){
                    tmp = tmp.substring(1,i);

                    if(tmp.contains(".")){
                        answer = Double.parseDouble(tmp);


                    }
                    break;
                }
                i++;
            } catch (Exception exception){
                break;
            }
        }
        if(answer != 0){
            alert(result);
            alert(answer);
        } else{
            alert(result);
        }



    }

    public static void alert(double value) {
        System.out.println("double: " + value);
    }

    public static void alert(String value) {
        System.out.println("String: " + value);
    }
}