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：

, W9 G% W. s# t. x3 J/ u public Object buildActions () {
    super.buildActions();
0 f% q; p- p2 m; g' P" z) o   
    // 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
" J2 l. y6 E1 y    // 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.
+ N. P; F( {+ a6 g" _+ m        
6 w) Q! s! |) r0 U( T    // Note we update the heatspace in two phases: first run
' a( F8 n0 [+ u3 O& f3 q    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
+ U, H/ A, c+ k0 w$ \$ Y        
1 @; l: r+ a3 F; N3 m    // 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
% v3 R9 r! g9 W0 H" R1 h    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
. H% w1 e- N' ?7 ^2 }    // 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).
) p7 _6 |6 j: y( n# K2 }   
    modelActions = new ActionGroupImpl (getZone ());
9 @# O2 ?2 i; A0 p3 c
0 ]( l" ]! K+ D    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
+ F7 y( }" J6 @      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
( l; v) p& D* o$ M4 _
  ^' k' V6 r1 [: w9 {) D    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
# ^& k! t/ z8 J- _4 [* E( p        new Selector (proto.getClass (), "heatbugStep", false);
( ]' |' h3 I7 \      actionForEach =
! z- k3 a. f& e+ _2 [7 z3 N, E. \        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
' u+ G; G# N2 A7 ~         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
! F- r# N) h) I0 j, N! v      e.printStackTrace (System.err);
' t& f) _; P5 ~; a    }
% [7 j5 e# y2 s5 D   
    syncUpdateOrder ();

    try {
; f" V1 n8 N# X+ X1 o. e% X      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
7 h$ N$ Z7 V- s. e# ]    }
2 V- Q( Y( P# C8 t        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
2 }6 ~/ J; y7 p) H  D    // has no notion of time. In order to have it executed in
5 J0 D2 d/ M, z9 K6 V; U* i/ A    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
# Y0 C+ c8 i; ]    // 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.

    // This is a simple schedule, with only one action that is
$ k8 a' _6 n  r$ ]" G: i; @1 U    // just repeated every time. See jmousetrap for more
$ X9 r9 Y: o! X( d) i# Y( `0 G    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
2 Q  N, K$ H$ z5 P; q9 _    return this;
+ `# l- i. o& C7 V" t  }