actorpool.java

一个关于J2ME的确游戏

public class ActorPool {
    private Actor firstFree;
    private Actor lastFree;
    private Actor firstUsed;
    private Actor lastUsed;
    private Actor oldUsed;



    public ActorPool(Actor[] initObjects) {
        if (initObjects == null || initObjects.length < 2) {
            return;
        }

        firstFree=initObjects[0] ;
        lastFree=initObjects[initObjects.length - 1];


        for (int i = 0; i < initObjects.length; i++) {
            if (i < initObjects.length - 1) {
                initObjects[i].setNextLink(initObjects[i + 1]);
            } else {
                initObjects[i].setNextLink(null);
            }

            if (i > 0) {
                initObjects[i].setPrevLink(initObjects[i - 1]);
            } else {
                initObjects[i].setPrevLink(null);
            }
        }
    }


    public Actor getNextFree() {

        if (firstFree != null) {

            if (firstFree.getNextLink() != null) {
                firstFree.getNextLink().setPrevLink(null);
            }

            Actor newFirstFree = firstFree.getNextLink();

            firstFree.setNextLink(null);
            if (lastUsed != null) {
                firstFree.setPrevLink(lastUsed);
                lastUsed.setNextLink(firstFree);
            }
            lastUsed = firstFree;

            if (firstUsed == null) {
                firstUsed = firstFree;

            }

            if (lastFree == firstFree) {
                lastFree = null;
            }

            Actor actorToReturn = firstFree;
            firstFree = newFirstFree;

            return actorToReturn;
        }
        if(oldUsed==null){
           oldUsed=firstUsed;
        }

        Actor actorToReturn = oldUsed;
        oldUsed = oldUsed.getNextLink();
        return actorToReturn;
    }


//   public void dump()
//   {
//      System.out.print("FREE LIST: ");
//      Actor a = firstFree;
//      while (a != null)
//      {
//         System.out.print("{" + a + "} ");
//         a = a.getNextLink();
//      }
//      System.out.println("");
//
//      System.out.print("USED LIST: ");
//      a = firstUsed;
//      while (a != null)
//      {
//         System.out.print("{" + a + "} ");
//         a = a.getNextLink();
//      }
//      System.out.println("");
//      System.out.println("LastUsed: {" + lastUsed + "} OldestUsed: {" + oldestUsed +
//                         "} firstUsed: {" + firstUsed +
//                         "} LastFree: {" + lastFree + "} firstFree: {" + firstFree + "}");
//
//   }


    public void release(Actor actorToRelease) {

            if (actorToRelease.getPrevLink() != null) {
                actorToRelease.getPrevLink().setNextLink(actorToRelease.
                        getNextLink());
            }
            if (actorToRelease.getNextLink() != null) {
                actorToRelease.getNextLink().setPrevLink(actorToRelease.
                        getPrevLink());
            }

        if (firstUsed == actorToRelease) {
            firstUsed = actorToRelease.getNextLink();

        }

            actorToRelease.setNextLink(null);
            if (lastUsed == actorToRelease) {
                lastUsed = actorToRelease.getPrevLink();

            }

            if (firstFree == null) {
                firstFree = actorToRelease;
                actorToRelease.setPrevLink(null);
            } else {
                actorToRelease.setPrevLink(lastFree);
                lastFree.setNextLink(actorToRelease);
            }

            lastFree = actorToRelease;

    }

    public Actor getFirstUsed() {

        return firstUsed;
    }

}