Question

Hi im new to this site and need help with a program im working on. the problem im having is that i cant seem to store string and two integers (as the coordinates). i have looked at other code but dont see how the values are stored. below is the code ive been using. the code seems to be fine but when trying to stored the values i cant put multiply integers. thanks for your time

import java.util.HashMap;
public class map {

    class Coords {
        int x;
        int y;

        public boolean equals(Object o) {
            Coords c = (Coords) o;
            return c.x == x && c.y == y;
        }

        public Coords(int x, int y) {
            super();
            this.x = x;
            this.y = y;
        }

        public int hashCode() {
            return new Integer(x + "0" + y);
        }
    }

    public static void main(String args[]) {

        HashMap<Coords, Character> map = new HashMap<Coords, Character>();
        map.put(new coords(65, 72), "Dan");
    }

}

Answer 1

There seems to be several issues:

• “Dan” is a String, not a Character
• case is important in Java (new coords(65,72) should be new Coords(65,72))
• Coords needs to be static to be instantiated without a reference to an instance the enclosing map class.

This should work:

static class Coords {
    ...
}

Map<Coords, String> map = new HashMap<Coords, String>();
map.put(new Coords(65, 72), "Dan");

ps: although you are allowed to name a local variable map within a class map, it is not a good idea to have such name collision. In Java, classes generally start in upper case, so you could rename your class Map. But it happens that Map is a standard class in Java. So call your class Main or Test or whatever is relevant. 😉