Aside from the typo on your code, it works for me.
import java.util.Comparator;
import java.util.PriorityQueue;
public class StackOverflow
{
public static void main(String[] args)
{
FuelPriority strategy = new FuelPriority();
PriorityQueue<Vehicle> incoming = new PriorityQueue<Vehicle>(4, strategy);
incoming.add(new Vehicle("car1", 10));
incoming.add(new Vehicle("car2", 20));
incoming.add(new Vehicle("car3", 15));
incoming.add(new Vehicle("car4", 1));
// to retrieve the elements in order
while (!incoming.isEmpty()) {
System.out.println(incoming.poll());
}
}
}
class FuelPriority
implements Comparator<Object>
{
public int compare(Object o1, Object o2)
{
Vehicle a1 = (Vehicle)o1;
Vehicle a2 = (Vehicle)o2;
return Integer.compare(a1.getFuelLevel(), a2.getFuelLevel());
}
}
class Vehicle
{
private String name;
private int fuelLevel;
public Vehicle(String name, int fuelLevel)
{
this.name = name;
this.fuelLevel = fuelLevel;
}
public int getFuelLevel()
{
return fuelLevel;
}
@Override
public String toString()
{
return name + "=" + fuelLevel;
}
}