Question

I have a Hashmap and i am struggling on how to print a single key and value. i am able to print all of them but would like to know how to just print one of them thanks

import java.util.HashMap;


public class Coordinate {

static 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 String toString()
    {
        return x + ";" + y;
    }


}

public static void main(String args[]) {

    HashMap<Coords, String> map = new HashMap<Coords, String>();

    map.put(new Coords(65, 72), "Dan");


    map.put(new Coords(68, 78), "Amn");
    map.put(new Coords(675, 89), "Ann");

    System.out.println(map.size());
    System.out.println(map.toString());

}
}

At the moment it shows

3
{65;72=Dan, 68;78=Amn, 675;89=Ann}

but would like it to just show

65;72=Dan

thanks for looking

Answer 1

The Map.get(K) method allows you to retrieve the value of a desired key. So you can do this:

Coords c = new Coords(65,72);
System.out.println(c + " -> " + map.get(c));

This works for any sort of Map, including HashMap and TreeMap. You can also obtain a set of all keys in the map using Map.keySet().