基于委托的车辆追踪器

/** 基于委托的车辆追踪器 */
public class DelegatingVehicleTracker {

	private final ConcurrentHashMap
 
   locations;
	
	private final Map
  
    unmodifiableMap; public DelegatingVehicleTracker(Map
   
     points) { locations = new ConcurrentHashMap
    
     (); unmodifiableMap = Collections.unmodifiableMap(locations); } public Map
     
       getLocations() { return unmodifiableMap; } public Point getLocation(String id) { return locations.get(id); } public void setLocation(String id, int x, int y) { if (locations.replace(id, new Point(x, y)) != null) System.out.println("invalid vehicle name : " + id); } }