import java.util.*;

/**
   Every Thing must implement this interface.  
   @author Ben Dugan, Hal Perkins
   CSE 142 Summer 2001, Homework 6
*/
public interface Thing {

  /** A Thing will receive this message once per simulation cycle,
      during the movement phase of the simulation. The thing should
      change its position, if it wishes to do so.
  */
  public void move();

  /** A Thing will receive this message once per simulation cycle,
      during the spawning phase of the simulation. The Thing may add
      any "children" to the given ArrayList.
  */
  public void spawn(ArrayList c);

  /** A Thing will receive this message once per simulation cycle,
      during the graphics window update phase.  The Thing should display
      itself. */
  public void display(GWindow g);
  
  /** A Thing must answer with its X coordinate in the world. */
  public int getX();

  /** A Thing must answer with its Y coordinate in the world. */
  public int getY();

  /** A Thing must answer with a string which describes what kind of
      thing it is, for example "Algae". */
  public String kindOfThing();

  /** A Thing must answer whether or not it consumes the given kind
      of thing.  For instance, an OilBlob would answer true if presented
      "Algae" or "Fish". */
  public boolean consumes(String kindOfThing);

  /** This method will be called when a Thing consumes the given kind
      of thing. */
  public void consume(String kindOfThing);
}