Remove your Comparable
interface, and use the Comparable
interface from the Java api.
And also, maybe you can change
public int compareTo(Object o) {
Item i = (Item) o;
if (this.getNumber() < i.getNumber())
return -1;
if (this.getNumber() < i.getNumber())
return 1;
return 0;
}
into :
public int compareTo(Object o) {
Item i = (Item) o;
if (this.getNumber() < i.getNumber())
return -1;
if (this.getNumber() > i.getNumber())
return 1;
return 0;
}