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：
! z  K. o' E: U7 E0 O2 J' T
; A& H- N# `- m, { public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
* j8 n' q6 }3 Y6 h( v. k+ k" \    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
. U0 ]/ ~: Y2 j. ?    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
: h) ^6 v. M8 w8 I  p* h    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
# d6 C9 m: D) ^. X" x4 a    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
% n" e0 z5 g, D8 G+ d: u8 ]    // 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
+ C/ X. H9 s0 m    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
2 ?7 I" n  r- M" x1 j; d/ t
    try {
; ?$ t1 ?; E( o& ^/ n6 y# X8 n/ W      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
# S. y0 d6 s* o3 _& i- z* C6 H      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
0 Z9 W8 m5 b" r3 G& B! e$ Y      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
& v5 y! O$ M) D- u0 r6 N        new Selector (proto.getClass (), "heatbugStep", false);
9 e5 g3 N, I! W      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
( W2 E6 U6 H8 n- w: n        (heatbugList,
$ _# L( o- w' W+ j         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
8 K' M: Y+ d& J, j+ @* z$ ]    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
; a1 G1 f% S. E( K5 n1 N2 W/ K! J    syncUpdateOrder ();
3 h0 f; v2 u" t) ?6 _
  {- S5 |8 s$ Q8 \    try {
6 x7 S! x7 \! K5 ?+ r$ O3 W      modelActions.createActionTo$message
: d% M& p1 ^6 U) G6 U        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
" h: I: y! t3 J" ~) I& B6 ^    }
        
    // Then we create a schedule that executes the
0 @! m  q* Y; G    // 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
* F0 H1 H- A# @5 R! P% P    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
, ^  S) w* }$ @' Q0 `  S( R5 [# W    // the beginning of the loop.
( l) l$ I% k# Y
$ ^. E. r% k- G) n4 w" |    // This is a simple schedule, with only one action that is
3 v5 y8 q4 k  \; A3 b' z8 H    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
$ g. i) F' F+ a. `; [+ R    modelSchedule.at$createAction (0, modelActions);
* \3 |' @/ n* C2 S% a- `$ T6 ]        
! }0 U" K/ G! s1 k' Z    return this;
  }