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：
# T4 W& r  ~" z! l" p9 B
public Object buildActions () {
2 u/ `; P/ m3 z7 x- R    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
    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
* W3 I3 i4 f; p' y4 c4 e3 P    // 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
% S( C' L; a, X# e6 D4 ?9 z    // `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
    // list from timestep to timestep
- [' A3 \* }2 K        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
& L- T0 _" t4 P$ {8 p5 K4 }* W2 a    // order of iteration through the `heatbugList' will be
( A4 U0 \3 f! v' K! I4 w    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
) \! k6 e: u/ Q, p6 W* w
* x: a* ?8 ?# H; K1 i# C    try {
      modelActions.createActionTo$message
- H3 m  v  I2 q9 N: R; H) e& w5 d        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
* |, J) Y: N# |7 Z& k      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
* w% p& m( J& ^/ j. T3 {! S      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
- n- e0 M# i  E) P        (heatbugList,
6 _7 E% t. f. g         new FCallImpl (this, proto, sel,
: x1 J* J* R  s1 X                        new FArgumentsImpl (this, sel)));
: N3 v0 L4 D7 W; C    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
2 G6 b7 `0 K3 B" g   
    syncUpdateOrder ();

    try {
" Q/ K* m. u9 {      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
( D$ ?3 `5 K& h4 Y" s+ i" u+ w0 Y      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
* J2 k5 a1 W. k! t& _/ m        
    // Then we create a schedule that executes the
4 F/ ]. f) m3 z$ ]3 ^2 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
* Q. _3 f; k9 F3 m) t) {, ^    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
; b) A# g6 W' e( g, m" F! [3 Y2 x    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
7 P6 m+ w) L# x" B) u" W    // just repeated every time. See jmousetrap for more
    // complicated schedules.
+ O8 Z1 i( _- i  f7 x  
; J0 @! A2 D$ B/ C7 u# F5 D    modelSchedule = new ScheduleImpl (getZone (), 1);
' N$ n0 P% _0 X    modelSchedule.at$createAction (0, modelActions);
        
( I+ k7 w* P! O# W    return this;
8 \2 i  f) f, Y9 u, v6 `1 Y7 K8 H1 z1 Y  }