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：
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public Object buildActions () {
  i% _1 J2 H" f& I, f# u- u9 D    super.buildActions();
   
    // 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
    // called <foo>". You can send a message To a particular
6 L4 d+ B: N: d% Z    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
+ z$ ^' o2 B6 x1 z2 G    // changes the heatbugs have made. The ordering here is
* d% ^$ s# y! A8 K6 [    // significant!
- r- E' o- a4 A5 j3 O9 q        
    // Note also, that with the additional
+ R- V! K+ `1 u0 r! w4 {    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
6 e) L2 [5 `7 V" [. h0 H6 d2 c7 D    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
, p. M/ x' ]3 ?% }4 b        
1 O; I# a0 F9 J2 t  d9 e# N    // By default, all `createActionForEach' modelActions have
* V9 I$ d5 L, j& ?9 y    // 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
2 c- u  g& k' a$ f    // indirectly by some other process).
1 x% H2 J) r& W( u   
    modelActions = new ActionGroupImpl (getZone ());

    try {
2 d1 H) H7 H% J- t" \' n1 G4 |      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
+ n4 R, y7 V4 \" A! O      Heatbug proto = (Heatbug) heatbugList.get (0);
# O+ w& n) X2 G( m- |: S      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
9 F9 C1 H! ]- L7 s* X0 R6 A# {# S& m        (heatbugList,
         new FCallImpl (this, proto, sel,
2 }0 i4 {% t& O) g                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();

9 D0 N& }. o$ H) y    try {
' j* Q- R$ a. b" ?& c      modelActions.createActionTo$message
& _0 d  q8 t' v) h" k. L3 V6 I        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
: y8 K: R; W! d% @' K9 A6 j: s        
    // Then we create a schedule that executes the
% I% A: R5 T% ~* Q+ l) t    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
/ M7 j. v' d( w' B6 F    // schedule has a repeat interval of 1, it will loop every
, G- d, z0 v8 p: D8 C    // time step.  The action is executed at time 0 relative to
0 U4 e: N5 ]; s9 o6 z- y    // the beginning of the loop.
: f+ P; [! d2 w; n6 |
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
7 |9 Q. x9 i# `- ?8 K    // complicated schedules.
+ q% U* i4 i. _+ K& c3 T  
! }2 V7 ?  `- Y" F  a0 T( V; }* K    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
9 [) E/ r$ W; I+ h) r4 T/ h        
& V1 S$ {6 q$ u# P& Q- \* y" x3 d    return this;
  }