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：

public Object buildActions () {
! F$ D- L. G$ [( x    super.buildActions();
% m% y7 n- n8 A" K+ F3 o  F) l7 R   
    // Create the list of simulation actions. We put these in
- a7 t2 o9 t6 ~$ @8 G    // an action group, because we want these actions to be
3 I) c5 C! G9 k9 [6 o    // 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.
8 {' r9 s: y( j: c        
    // 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!
        
* A9 c: S0 ?$ {& s    // Note also, that with the additional
  u4 R$ C% w( ^+ b8 G  c    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
" C( {" u' q" Z3 X4 R; O    // systematic bias in the iteration throught the heatbug
) x! A: @, H% d: ^- W: _/ O    // list from timestep to timestep
2 E0 S/ b. e6 M$ s& m# ^2 \        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
6 I+ T' K4 _9 Z( _8 b; |# X. J    // order of iteration through the `heatbugList' will be
5 h  J0 I8 q% W    // identical (assuming the list order is not changed
    // indirectly by some other process).
& f% Y' d5 Q- P   
    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
) N' @' @; ]+ I8 G: @8 K; j        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
6 x* v. g4 r4 w2 H4 `7 f    }
. K0 S% o0 N# l) j- @/ E
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
& S+ }; F! R. A& H* o! B% R        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
2 k; d% X8 A7 y* _- m7 P         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
7 [  ^/ N; ?# V) X4 T   
3 l, F0 T; u! r2 y4 f) ^    syncUpdateOrder ();

; i+ u. o6 C9 i/ s    try {
: e7 u. {( o2 z2 ~* h      modelActions.createActionTo$message
6 I7 j$ a% v) L6 P' l  k        (heat, new Selector (heat.getClass (), "updateLattice", false));
4 T- P& k" }) P- u    } catch (Exception e) {
3 s& i7 P3 o5 h+ B; x$ q7 {7 \3 \! A      System.err.println("Exception updateLattice: " + e.getMessage ());
" b$ D6 x* S' i; b& b0 p& v. ^    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
7 H* p* O8 }" Z% y    // 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
    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
+ v7 {. Z3 u+ W3 ?  p7 {/ J' z
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
/ c& l& T' J% F8 v0 j6 j  
0 E( G; O+ S8 r9 I    modelSchedule = new ScheduleImpl (getZone (), 1);
0 _/ f1 X: Y' B0 B4 }    modelSchedule.at$createAction (0, modelActions);
7 M8 t# y3 ]# s* W- A        
2 S( o, k4 q  `1 E( |    return this;
. \& i. N9 {3 B  }