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：

6 g$ D  F# Z  ~/ r) f public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
4 h2 i4 U* c1 U    // an action group, because we want these actions to be
6 D% T+ Z- }+ `  q0 C6 q7 k" h$ ]    // executed in a specific order, but these steps should
% M1 D0 U. G& n  i; M    // take no (simulated) time. The M(foo) means "The message
+ X, f" C5 L) E: L" j7 z    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
" v8 A0 a* b5 |* A    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
9 d0 E9 l! O- t    // changes the heatbugs have made. The ordering here is
3 i4 |2 q9 q6 H. r) \2 [    // significant!
        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
! Q1 Y; Q8 v+ N1 P5 r$ `    // randomize the order in which the bugs actually run
  q0 u* ]7 y! F; E    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
1 u$ X  b2 c0 V    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
+ n/ ?4 l: N/ n; V. O" ~9 l    // 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
    // indirectly by some other process).
. f2 }+ Y2 h$ N   
    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
" R, `- p8 @9 L  h. Z    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
) b4 o6 {. m  i. R- t/ L
    try {
; C* Z8 l2 S& l$ C5 y' T6 K      Heatbug proto = (Heatbug) heatbugList.get (0);
5 z) i( B! A( G4 `( H1 J7 S6 M      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
: j7 e  e* O2 A, |! y/ A1 f" v      actionForEach =
; D' q- h) a5 ~. ~/ ?& _5 J: @7 P9 z        modelActions.createFActionForEachHomogeneous$call
7 {( R" l* C+ k: f1 I" t        (heatbugList,
% M* ^1 Z* V" g1 t- X3 `  J         new FCallImpl (this, proto, sel,
- ~  f+ z4 `& x% ?                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
! J9 U$ A# _4 I" z      e.printStackTrace (System.err);
/ x; w2 I( O, {; p" Z    }
) [1 r/ {  g; r: @   
    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
+ ^! j  |, ~& Y$ y5 R. w        (heat, new Selector (heat.getClass (), "updateLattice", false));
2 A) j& {/ y: {+ e5 Y# Y6 i    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
* j: m6 r6 Y0 t    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
4 Q. v) B1 Z( P. ?    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
: n1 E+ v$ J5 f: l    // time step.  The action is executed at time 0 relative to
1 F0 q3 l! ~2 |) t    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
6 A5 m6 G) t+ |* D, a5 ~% f    // complicated schedules.
  
' V$ G; g5 F! {  n! s: G  g    modelSchedule = new ScheduleImpl (getZone (), 1);
$ t) R3 z6 K4 ]2 o7 U5 R8 A    modelSchedule.at$createAction (0, modelActions);
        
3 o1 I& p4 x! N' }6 c    return this;
  }