/**
 * Implement a sortable object based on numbers.
 */

public class IntegerKey implements SearchKey {
    int value;

    public IntegerKey(int a) { value = a; }

    private void verifyType(SearchKey o) {
        if (! (o instanceof IntegerKey))
            throw new RuntimeException("You cannot mix keys here.");
    }

    public int compareKey(SearchKey o) {
        verifyType(o);
        return (((IntegerKey) o).value - value);
    }

    public boolean equalKey(SearchKey o) {
        return compareKey(o) == 0;
    }
}