java - How to calculate difference between String times -

i have string of: "9am-5pm" subtract these 2 numbers , find difference in hours.

int intervalhours(string input) {     string[] ts = input.split("-");         // {"9am", "5pm"}     return tohours(ts[1]) - tohours(ts[0]);  }  int tohours(string t) {     int h = integer.parseint(t.substring(0, t.length() - 2));     if (t.endswith("pm"))         return h == 12 ? 12 : (h + 12);     else          return h == 12 ? 0 : h; }  // ...  system.out.println(intervalhours("9am-5pm"));