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：
' R3 @" W% y- j# _
; k/ h& J! M% ~4 N* Q public Object buildActions () {
    super.buildActions();
( a$ O$ O) P0 N. p   
    // Create the list of simulation actions. We put these in
$ c; t* K, n- L    // an action group, because we want these actions to be
! u, D- {1 e% j( j# V5 ?    // 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
. h/ F- I  h8 u9 O. Q3 Z    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
* t; {4 |. ~( n+ I& l- J    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
# x$ r. F4 e6 d8 r- L3 t2 Z    // significant!
& ?8 l0 |, l* z        
) ?' d: p/ f8 j+ \2 t! _    // Note also, that with the additional
0 t9 \3 C8 v+ u! s: R    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
8 U  G: K& O$ p) Q9 i  w2 Y) g. Q/ Q    // systematic bias in the iteration throught the heatbug
- d3 L# J; A6 ^* c) c- Z1 m; I    // list from timestep to timestep
        
0 G3 Y; ^3 q9 x: f& k    // 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 ());
) D) W/ W$ k# b
# m+ e% Y# q- a9 S    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
, ^$ O: N3 h' P* C    } catch (Exception e) {
  p3 T7 G6 Z6 ]      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
2 P1 F7 X! X7 w) i. G. c# Y
    try {
' D# s9 ^+ y( L- ]' |$ `' L      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
) b! V( K- q6 a- R' p8 k        new Selector (proto.getClass (), "heatbugStep", false);
: ?. Z! N3 e& L9 Q4 f; ~2 ^* s      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
1 ?! m1 P1 V2 s: E        (heatbugList,
! y5 r  r" y. j9 M         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
" Q& F: v5 R# W+ `3 Y8 Y4 I" x    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();

; z5 F5 h. j9 \/ `. i' P# k    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
5 F( a2 ~: M% q    } catch (Exception e) {
) U4 D, e7 N3 s4 W( }      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
5 R# N2 @( ^; g        
    // Then we create a schedule that executes the
* l' Z) n9 ?5 t6 E) M    // modelActions. modelActions is an ActionGroup, by itself it
' W8 ?2 \0 N, y; g2 e    // 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
$ ~: d1 J2 g$ o+ y# |9 f/ j    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
! {2 D2 J- I% ^; K+ C
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
# d2 _. l5 ]5 u# a4 o9 k4 G    // complicated schedules.
$ G; f' n' \. ]: w. I$ n' X$ G  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
' U3 |2 R: N1 @' m2 C5 H1 O. W    return this;
' ~2 @* X% a8 H- {8 X  }