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 () {
- ?" w- b. X5 M+ @) {6 c    super.buildActions();
. g8 m( t4 V1 O% U) Z   
    // 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
8 W* Q3 }6 x+ H6 x7 s    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
3 e( u& k' z+ X5 B2 {        
    // Note we update the heatspace in two phases: first run
4 n# L( m$ Y$ q1 y4 e    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
; R+ [. j) C; B0 I. p- g! n( \4 K    // significant!
" x1 @' E9 n( A- s        
# N& f3 N3 b( r" @# D" H/ S    // 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
5 _2 a/ q4 B- D$ r7 Q7 Q    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
3 z5 V' ^3 v1 m$ u1 `  b        
    // By default, all `createActionForEach' modelActions have
4 g% L) O* w( T# ]5 l    // 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 ());
; O  u8 B+ S2 ], W+ i9 s
    try {
/ c) E" B6 C& s' ]* Y4 `6 ^) V8 ]1 C      modelActions.createActionTo$message
1 b6 o/ z; Z. @; }2 u1 D1 ]        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
* G1 X3 B7 e$ s- D' p    }

1 {7 B" w1 I8 m" \; E    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
& x  A' s% M: Z8 Z% `      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
' A: p  v- q, v- T, \8 V$ T         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
) G* b6 X  |- u1 W      e.printStackTrace (System.err);
9 G: d) X8 H) ^; c! G    }
5 v# G: e0 u3 }2 @. g   
% Q: M8 T6 p% h/ c: t    syncUpdateOrder ();
) [4 Y; L# |  u  W* p1 E# N
6 s# a4 K9 v) \" C    try {
6 x! f( z/ ~* \+ k      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
; E% k) G* O$ C) Q* e$ [    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
$ D  X% |( d+ J" O0 D. d/ @    // 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
; R( L6 ]$ c0 K. s- T+ w. \$ \6 S    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

* o8 ^7 t* \7 i% ~    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
0 W- |8 U# i( ]    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
2 x+ ]: {7 X; B4 t( c    return this;
  }