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 () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
: C) z' ?6 M0 g$ H    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
% i6 }% p- @+ }' s: @* E    // called <foo>". You can send a message To a particular
2 L4 ?1 i* E8 \% X' F0 Y9 J    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
: M& R: a8 H- Q/ H$ M/ n    // diffusion, then run "updateWorld" to actually enact the
% k- P6 ]0 ]. ?  t6 {    // changes the heatbugs have made. The ordering here is
  E" ^* @5 U: W6 u    // significant!
        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
1 }  x) K  I- n5 i    // randomize the order in which the bugs actually run
2 i: p) R) j& u# E    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
6 E- E/ Q+ v1 l% \1 A5 c) {    // list from timestep to timestep
' u' @) R4 P9 o8 c        
( a/ E7 B7 `7 }+ M: }9 |1 Y    // 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).
6 g; v1 D/ L7 r- ~8 T% x5 C   
4 U% I2 u! a+ `& [' B1 s$ G7 P    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
1 g9 J# n4 ?6 O% T& M    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
8 ]( b9 J1 I' b' f8 f      Heatbug proto = (Heatbug) heatbugList.get (0);
! O1 |9 L% X+ r      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
  H- a3 W7 z% U" ]0 M5 i% }  c      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
! u  v7 y# y% j$ j1 j$ Y      e.printStackTrace (System.err);
    }
; C& ?$ C' v6 J' Z* R   
    syncUpdateOrder ();
( a2 ~$ h- ^2 ~3 P7 ?- }, a
* x" y/ j$ U& ~, b    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
  a) X( J. l5 X1 j+ t: k) [    } catch (Exception e) {
0 O5 s5 s0 @% Z      System.err.println("Exception updateLattice: " + e.getMessage ());
* [- ^8 S* z) h" T# e. g    }
        
    // Then we create a schedule that executes the
    // 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
    // schedule has a repeat interval of 1, it will loop every
( i4 V" u: H1 R/ ]    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

) r- s; L! ]9 T% ]4 ^! g    // This is a simple schedule, with only one action that is
& [2 v6 a! m  e7 z; T    // just repeated every time. See jmousetrap for more
* C- _9 e$ n1 n. `    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
! ?" k6 O! \' c6 L6 \- Z        
9 r6 p" J  ~8 S2 |1 d7 x+ r    return this;
  }