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：
7 o( I9 D) ~( `- P- Y
public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
# g0 ^1 i# b6 V5 s1 u) W6 `8 i    // an action group, because we want these actions to be
2 d' A9 J; O& _8 }. w6 u! y+ l/ S    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
* C4 f* T: [$ y; s1 W    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
) p0 t- M6 b" a) P    // diffusion, then run "updateWorld" to actually enact the
; U, V& O3 j! r    // changes the heatbugs have made. The ordering here is
    // significant!
  I2 \# |2 N$ V        
    // Note also, that with the additional
4 l% S! n3 ?2 v) Y) u8 k. A" g% \    // `randomizeHeatbugUpdateOrder' Boolean flag we can
0 j% v  f2 }- @2 Y' y    // randomize the order in which the bugs actually run
& c+ |) w, e# {/ m    // their step rule.  This has the effect of removing any
) i7 T9 ~5 d0 }/ s2 P2 C; m    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
& D7 M* ~( I# b; m' @        
8 |% A% j! `2 q. ^& `$ a5 J    // By default, all `createActionForEach' modelActions have
' T: _' Q4 {' s2 u& m# Z7 e3 i2 z    // 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).
   
    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
/ C3 Q$ d, a  D$ Q2 A3 G. n6 u        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
9 M& q5 b9 b* }/ H0 u$ G6 m4 q      System.err.println ("Exception stepRule: " + e.getMessage ());
& R4 ~" b' z/ [, ?8 Y7 \/ }; f    }

    try {
4 M/ I5 ?! \1 _, H5 b- Q8 b. q: Z      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
6 R% `# R6 P- r        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
; D6 }+ i2 k+ u; D6 \        (heatbugList,
         new FCallImpl (this, proto, sel,
+ }# B9 s4 A( |  v9 Z  f                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
7 _7 ]6 E8 K0 R* |3 D, L      e.printStackTrace (System.err);
/ ~& m$ k5 ]1 b    }
   
1 F# {5 `) f1 q" Z! s' m+ f    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
- u3 i# V) l2 t% g% m- A    // Then we create a schedule that executes the
+ M8 H% J0 W7 F1 j! B; z# p    // 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
    // schedule has a repeat interval of 1, it will loop every
6 N" q# N; D& ^- ]/ U    // 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
    // just repeated every time. See jmousetrap for more
) d. Y" Y+ i0 n+ r    // complicated schedules.
4 T  g7 V, q% K. H  
    modelSchedule = new ScheduleImpl (getZone (), 1);
" L# N+ P: I6 I' s    modelSchedule.at$createAction (0, modelActions);
" g$ ^1 C$ _8 h7 w        
/ `8 o1 f' U' |    return this;
  }