static List<String[]>  list=new ArrayList<String[]>();
    static {
        list.add(new String[]{"1","0","A"});
        list.add(new String[]{"2","1","B"});
        list.add(new String[]{"3","1","C"});
        list.add(new String[]{"4","2","D"});
        list.add(new String[]{"5","3","E"});
        list.add(new String[]{"6","5","F"});
        list.add(new String[]{"7","0","G"});
        list.add(new String[]{"8","7","H"});
        list.add(new String[]{"9","3","I"});
    }
    public static void test(String n,int lvl){
        String p="";
        for(int i=1;i<lvl;i++){
            p+="---";
        }
        for(String[] d:list){
            if(d[1].equals(n)){
                System.out.println(p+d[0]+"--"+d[2]);
                test(d[0],(lvl+1));
            }
        }
    }
    public static void main(String[] args) {
        test("0",1);
    }