Self Referential Puzzle check

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

public class Scratch {
    public static void main(String[] args) throws Exception {
        List<String> valid = new ArrayList<String>();

        for(String s : getStrings("")) {
            if(checkString(s)) {
                valid.add(s);
            }
        }
        if(valid.isEmpty()) {
            System.out.println("No valid");
        }
        for(String s : valid) {
            System.out.println(s);
        }
    }

    public static List<String> getStrings(String s) {
        List<String> r = new ArrayList<String>();
        if(s.length() == 10) {
            r.add(s);
            return r;
        }

        for(char c = 'A'; c <= 'E'; c++) {
            r.addAll(getStrings(s + c));
        }
        return r;
    }
    public static boolean checkString(String s) throws Exception {
        for(int i = 0; i < 10; i++) {
            char letter = s.charAt(i);
            Method m = Scratch.class.getMethod("Q" + i + letter, String.class);
            boolean b = (boolean)m.invoke(null, s);
            if(!b) {
                return false;
            }
        }
        return true;
    }

    public static int substringCount(String s, String sub) {
        int index = s.indexOf(sub);
        int count = 0;

        while (index != -1) {
            count++;
            s = s.substring(index + 1);
            index = s.indexOf(sub);
        }

        return count;
    }

    public static boolean Q0A(String s) {
        return s.indexOf("D") == 7;
    }

    public static boolean Q0B(String s) {
        return s.indexOf("D") == 6;
    }

    public static boolean Q0C(String s) {
        return s.indexOf("D") == 5;
    }

    public static boolean Q0D(String s) {
        return s.indexOf("D") == 4;
    }

    public static boolean Q0E(String s) {
        return s.indexOf("D") == 3;
    }

    public static boolean Q1A(String s) {
        return s.charAt(2) == s.charAt(3);
    }

    public static boolean Q1B(String s) {
        return s.charAt(3) == s.charAt(4);
    }

    public static boolean Q1C(String s) {
        return s.charAt(4) == s.charAt(5);
    }

    public static boolean Q1D(String s) {
        return s.charAt(5) == s.charAt(6);
    }

    public static boolean Q1E(String s) {
        return s.charAt(6) == s.charAt(7);
    }

    public static boolean Q2A(String s) {
        return substringCount(s, "E") == 1;
    }

    public static boolean Q2B(String s) {
        return substringCount(s, "E") == 2;
    }

    public static boolean Q2C(String s) {
        return substringCount(s, "E") == 3;
    }

    public static boolean Q2D(String s) {
        return substringCount(s, "E") == 4;
    }

    public static boolean Q2E(String s) {
        return substringCount(s, "E") == 5;
    }

    public static boolean Q3A(String s) {
        return substringCount(s, "A") == 1;
    }

    public static boolean Q3B(String s) {
        return substringCount(s, "A") == 2;
    }

    public static boolean Q3C(String s) {
        return substringCount(s, "A") == 3;
    }

    public static boolean Q3D(String s) {
        return substringCount(s, "A") == 4;
    }

    public static boolean Q3E(String s) {
        return substringCount(s, "A") == 5;
    }

    public static boolean Q4A(String s) {
        return true;
    }

    public static boolean Q4B(String s) {
        return substringCount(s, "A") == substringCount(s, "B");
    }

    public static boolean Q4C(String s) {
        return substringCount(s, "A") == substringCount(s, "C");
    }

    public static boolean Q4D(String s) {
        return substringCount(s, "A") == substringCount(s, "D");
    }

    public static boolean Q4E(String s) {
        return false;
    }

    public static boolean Q5A(String s) {
        return s.lastIndexOf("B") == 4;
    }

    public static boolean Q5B(String s) {
        return s.lastIndexOf("B") == 5;
    }

    public static boolean Q5C(String s) {
        return s.lastIndexOf("B") == 6;
    }

    public static boolean Q5D(String s) {
        return s.lastIndexOf("B") == 7;
    }

    public static boolean Q5E(String s) {
        return s.lastIndexOf("B") == 8;
    }

    public static boolean Q6A(String s) {
        return Math.abs((int)s.charAt(6) - (int)s.charAt(7)) == 4;
    }

    public static boolean Q6B(String s) {
        return Math.abs((int)s.charAt(6) - (int)s.charAt(7)) == 3;
    }

    public static boolean Q6C(String s) {
        return Math.abs((int)s.charAt(6) - (int)s.charAt(7)) == 2;
    }

    public static boolean Q6D(String s) {
        return Math.abs((int)s.charAt(6) - (int)s.charAt(7)) == 1;
    }

    public static boolean Q6E(String s) {
        return s.charAt(6) == s.charAt(7);
    }

    public static boolean Q7A(String s) {
        return s.charAt(7) == s.charAt(0);
    }

    public static boolean Q7B(String s) {
        return s.charAt(7) == s.charAt(1);
    }

    public static boolean Q7C(String s) {
        return s.charAt(7) == s.charAt(2);
    }

    public static boolean Q7D(String s) {
        return s.charAt(7) == s.charAt(3);
    }

    public static boolean Q7E(String s) {
        return s.charAt(7) == s.charAt(4);
    }

    public static boolean Q8A(String s) {
        return (substringCount(s, "B") + substringCount(s, "C") + substringCount(s, "D")) == 3;
    }

    public static boolean Q8B(String s) {
        return (substringCount(s, "B") + substringCount(s, "C") + substringCount(s, "D")) == 4;
    }

    public static boolean Q8C(String s) {
        return (substringCount(s, "B") + substringCount(s, "C") + substringCount(s, "D")) == 5;
    }

    public static boolean Q8D(String s) {
        return (substringCount(s, "B") + substringCount(s, "C") + substringCount(s, "D")) == 6;
    }

    public static boolean Q8E(String s) {
        return (substringCount(s, "B") + substringCount(s, "C") + substringCount(s, "D")) == 7;
    }

    public static boolean Q9A(String s) {
        return true;
    }

    public static boolean Q9B(String s) {
        return true;
    }

    public static boolean Q9C(String s) {
        return true;
    }

    public static boolean Q9D(String s) {
        return true;
    }

    public static boolean Q9E(String s) {
        return true;
    }
}