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：
# A# I) R% j& r4 {. o
public Object buildActions () {
) |9 U! p4 E% R  s& q    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
7 z0 D5 m' M$ D2 R) d0 Q    // object, or ForEach object in a collection.
  q1 z$ }# v& d: H2 k  H        
    // Note we update the heatspace in two phases: first run
) v$ r' ^' N& n+ F$ J4 \2 }    // diffusion, then run "updateWorld" to actually enact the
. \% z7 B3 F7 H) W% ?    // changes the heatbugs have made. The ordering here is
& a. ]$ W& @+ T    // significant!
        
# }( A; N, Z/ n+ z) H6 x' H    // 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
6 Y. D6 j% p# [. m    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
- f4 Z& r. R. M6 @8 G3 I    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
8 d# m  Y- W0 D$ k$ i    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
* _0 c( O8 R) L6 [! E7 ]
6 h: s& G( y  ~2 |- Z    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
2 p9 Y2 k  }. z8 }, u    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

0 z: l6 T" i9 |1 _" M    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
6 u! F$ }" l% i' Z      Selector sel =
, W" t+ f- T2 G& b        new Selector (proto.getClass (), "heatbugStep", false);
5 _; S5 K; ^, l      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
% k  \7 J  @* H9 J! P1 I        (heatbugList,
. _7 p' ]4 Q/ P7 h7 h         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
8 {- k# E. V- T' ^& L    } catch (Exception e) {
+ M9 a8 k5 E  {) s! G      e.printStackTrace (System.err);
    }
   
$ j% y" U: |# S6 m4 ^0 z- G    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
) }) m" E/ _; g& f    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
5 A7 I) D3 l# @5 Q6 L" A8 N" Y3 X    }
! d9 |3 `: b# V3 L; O) A3 l        
    // Then we create a schedule that executes the
6 e9 X4 f& w) j5 ~$ B& o    // modelActions. modelActions is an ActionGroup, by itself it
0 t+ v8 N) L% t  A+ o/ Q: L    // has no notion of time. In order to have it executed in
: g5 m2 ~0 u) \: x2 q" Y4 U* ?3 k    // time, we create a Schedule that says to use the
: \& I! U- m, p# D- P( l4 u; Z4 S4 s    // modelActions ActionGroup at particular times.  This
( O/ ^$ I( l, Z, K    // schedule has a repeat interval of 1, it will loop every
, T1 c2 n( f8 C8 t+ U    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
" X+ h. |7 v9 b
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
' F, E" w- N% M    // complicated schedules.
  
+ V6 u( J7 \$ y. n! [    modelSchedule = new ScheduleImpl (getZone (), 1);
0 u- U# ^) a5 a/ X+ {( k. y    modelSchedule.at$createAction (0, modelActions);
+ u& I) m# b" ?. u9 n; X$ z        
    return this;
  }