问jheatbugs-2001-03-28中某些代码

sybbk

HeatbugModelSwarm中buildActions部分，3个try分别是做什么？查了下refbook-java-2.2，解释太简略，还是不懂，高手指点，谢谢！代码如下：

public Object buildActions () {
2 k( f5 G9 N& z# o7 b" t    super.buildActions();
3 q/ g3 P% Q2 M+ c   
9 ?2 w/ b$ p: T9 r+ R    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
0 \- B4 r+ t7 b    // executed in a specific order, but these steps should
, I. V- z# |) T  w8 G$ t* ]    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
( g  L) h2 \2 L% {; [/ D- K        
. }7 M) K, Y. h+ [    // Note we update the heatspace in two phases: first run
8 D7 w  L# n+ L; S    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
4 w! z- R% H: k9 i( T4 z        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
8 p, r0 S5 u! \/ W    // list from timestep to timestep
# |0 N  M% @9 G# ]# V        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
- G2 G( a3 p9 h$ E3 M    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
% P- z; r, Z( Z- x7 @) ~+ |
1 f- T$ X# a4 n* Q$ D4 d    try {
      modelActions.createActionTo$message
, {% }6 ^" @# J1 `        (heat, new Selector (heat.getClass (), "stepRule", false));
' B3 d9 o; M( V0 e& P    } catch (Exception e) {
/ e  l0 `  h5 w& |+ z      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
! V0 n; q$ H( z) K, y        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
3 P1 D8 y# K( v- q        modelActions.createFActionForEachHomogeneous$call
* u1 ?! c! u8 N4 v5 N7 c        (heatbugList,
         new FCallImpl (this, proto, sel,
2 M: a( {* L- V3 n* T. A                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
# z! K4 f; R4 ]2 v  b* u( ?    }
   
6 h" A& \! J0 k    syncUpdateOrder ();

    try {
* ]$ G: [  l( M" I- _2 n' c      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
( B1 I" n3 H* D9 F3 Y! G; s4 {4 D- m    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
( Q/ E/ j( A( C2 i    }
6 V% u+ J2 o1 S! M/ w        
. }0 b# D6 J+ a. P- [! f: W    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
0 P/ R3 v) p' r- W, S4 X* W    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
; n! u: @, t" |! d
    // This is a simple schedule, with only one action that is
) O/ {4 i9 T$ q; ?% V    // just repeated every time. See jmousetrap for more
0 N( U$ z9 k7 F% x    // complicated schedules.
' t' y, d4 t7 h0 g8 M: o7 L7 ]  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
* m& s9 ~0 a# v8 D" ]        
# \9 o+ P% W# @  Z2 Q/ `1 B; K# c    return this;
  }