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：
# _+ @4 o6 f9 |; K, @' G
1 l! o2 y( ~1 p: H# @ public Object buildActions () {
    super.buildActions();
$ ?1 L6 a$ A7 z/ j: G3 s6 e. o   
$ V( f0 j4 j& A4 o& Y    // Create the list of simulation actions. We put these in
1 Z8 R% }4 ]. v8 R- k# F+ D$ p    // an action group, because we want these actions to be
5 J' }; ?+ }" t% P5 b" w* J    // 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.
- j) x% V) `; P1 I, C3 K6 k7 F% ~: s        
    // Note we update the heatspace in two phases: first run
0 p: L; U% r8 s' |; q2 h8 {    // diffusion, then run "updateWorld" to actually enact the
0 s# V  J& c4 I    // changes the heatbugs have made. The ordering here is
- f% R+ Z* X- o" g7 n$ Q    // significant!
        
    // Note also, that with the additional
7 j- B4 y$ A+ q+ P- T& Y; W    // `randomizeHeatbugUpdateOrder' Boolean flag we can
. U' q$ {  ?/ q6 `2 a    // 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
) S; V6 s5 ]- `& h) z! H    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
    // 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$message
: L- X6 a* ]3 \' n        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
# a" O4 u9 c/ u& r9 [8 v    }
' O. C0 H' x3 v$ h& [
" \& K$ C( i" y. Y0 N6 j    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
8 c, K- W: N# V, e7 A  h$ T        new Selector (proto.getClass (), "heatbugStep", false);
/ Z$ D, T& Q7 U3 ?      actionForEach =
9 m' a6 O' i/ U! h0 G) v6 N        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
, E: _. z& @" q         new FCallImpl (this, proto, sel,
5 Z) h# t9 `* s* C2 @2 b/ f# ~                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
" T  e) Q; U$ U2 @; g      e.printStackTrace (System.err);
    }
   
1 B6 h* Z8 P8 ^6 \    syncUpdateOrder ();
. P  L! ~  ?" ^$ v
) }: M1 I& X0 ~- S) P1 ]. X    try {
% V6 ~5 k8 @- M1 t1 }. j- B      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
: z) N: n, A0 C* q2 ^) y      System.err.println("Exception updateLattice: " + e.getMessage ());
6 p& q, }$ t3 v    }
/ l1 M" {& x6 Z) a, }        
. B: `, \: v2 n5 j    // Then we create a schedule that executes the
2 S1 N4 l' z' b3 v7 r# x& {: k    // 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
% l- s6 v4 C$ U! |0 w1 I    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

9 b' _' P3 ~+ L' D- X    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
# z8 E7 x6 k+ ?2 S) e    // complicated schedules.
  
7 p" E1 M# S# q# p% j" w' Z/ A! d    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
- {- K( f2 Y% i    return this;
  }