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：
& }. ?: m8 a6 w6 }
% h- I9 X4 p2 W3 A8 Y9 ^3 r public Object buildActions () {
7 K7 ~! v* f3 j2 h3 ~+ [2 a    super.buildActions();
6 r3 [% q% W; H; H3 ]   
    // 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
2 Q  V( t+ Z( ^8 S    // 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.
        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
; R3 \' e& M, g, c( z    // changes the heatbugs have made. The ordering here is
/ p& ?6 L; X. a    // significant!
        
    // 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
9 Q  I6 C, \9 i! w    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
: m6 o- L' ]" a; Z) V0 R# x    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
, x5 Z- u: f' }    // indirectly by some other process).
% l# j: j$ w; w; v   
    modelActions = new ActionGroupImpl (getZone ());
9 B: a9 K' r  q! B3 R
4 h2 A4 k6 v) u2 W3 ^! A    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
$ h5 m8 U7 W* h+ S5 \4 o, A    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
9 i; }+ x& ~) l! X, M      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
- d4 t7 c+ T6 L        modelActions.createFActionForEachHomogeneous$call
) m& v( s" l* T        (heatbugList,
% h1 i+ c3 d$ g  s8 }6 J, g         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
8 o- Q$ U' L7 L    } catch (Exception e) {
      e.printStackTrace (System.err);
) E& k* c+ b8 d+ o& e! a" ]3 L    }
   
    syncUpdateOrder ();

* k7 K7 t" Z; y$ R    try {
5 e3 K1 b0 N+ `6 k8 y      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
) I" i$ t3 H  D, Q( Z! M    // has no notion of time. In order to have it executed in
- I) D7 H5 ~* I% }' c: T    // time, we create a Schedule that says to use the
1 B7 X& a( D% D8 x; P    // modelActions ActionGroup at particular times.  This
0 [) X3 _% B" d( }    // 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.
. |8 |9 T; ^- F: r6 J
    // This is a simple schedule, with only one action that is
; h8 q1 x& A3 V3 j% U    // just repeated every time. See jmousetrap for more
9 y6 c% K4 Q& q) C% o    // complicated schedules.
  
& [+ P7 ~- y# P& n. Z2 I# p    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
# u2 i. n# A4 d8 Z        
+ X+ e/ p( [5 H' b3 ?    return this;
/ h2 B' O/ U) |) M; T9 C  j  }