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：

" b3 P9 U) {7 I public Object buildActions () {
    super.buildActions();
) i/ M8 ~7 P+ [: X1 m   
" f" n- W3 \! c4 Z: |  x    // 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
" y2 \' c7 n2 m" H8 h! A- M: Z    // called <foo>". You can send a message To a particular
+ g- D/ k/ C5 w' ~    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
% P3 V0 w0 r2 r+ s1 i, Z  D    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
5 F4 I, U6 G9 c+ p        
) I9 V/ }) v) @4 l0 Y    // 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
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
* w3 w& Y4 V5 l8 `: ^; @    // a default order of `Sequential', which means that the
- T+ x# \1 Q* T8 `7 X$ B% e    // order of iteration through the `heatbugList' will be
  A" X% P( V1 |# B4 L- P8 K: w' t    // identical (assuming the list order is not changed
5 T+ L4 H" c' n: f' k7 p* X3 d    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
" B3 `/ r1 y1 e# ?$ y3 x7 j: n; Y& ?
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
* `# S/ _9 \6 `) E( |    } catch (Exception e) {
  \+ Q. [6 k* ^% p, ?2 u      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
6 d1 _' N% Z4 u
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
1 Y; s  `* i& T7 r# j6 W        (heatbugList,
         new FCallImpl (this, proto, sel,
, q4 `. h3 ]! _3 B: g  R                        new FArgumentsImpl (this, sel)));
. Q5 h9 e' C: A5 ?* G    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();

5 _  Q& ?; |2 v% N0 u, T    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
. a% u/ o8 _# ^$ K( V      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
) T+ `. m1 Z2 L' \, |/ w4 z/ Q    // has no notion of time. In order to have it executed in
; }  ?- X, F1 L' N* f2 b    // time, we create a Schedule that says to use the
1 u6 J( r9 q5 \  s    // modelActions ActionGroup at particular times.  This
  i2 n, b5 s& R8 M: _9 X' C    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
" v+ p" h) |% a# F) Z    // the beginning of the loop.
, f5 l8 `1 M* x. C$ q
/ t/ e/ t! ]+ }( i  |/ x    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
/ q5 M- L- g5 ~( E+ W' o  ?' [8 m. G0 n" S) I    // complicated schedules.
/ y+ _% }* E! H  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
! C4 G: Z# T% T) l2 ]( m) ~/ \        
    return this;
  }