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();
) u1 u; D: Y# k   
) C+ Y/ ~, I+ }0 e: M. S6 |2 ]. \    // 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
3 F  s4 Y8 |& g5 k- l- }    // called <foo>". You can send a message To a particular
" z/ |% ^* ^6 e; w% B* S. J6 D    // object, or ForEach object in a collection.
        
2 i6 c& R. l( I! X    // Note we update the heatspace in two phases: first run
" r, P# q' B4 B& I    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
# X  T3 C9 ~( ~$ T6 D) r; W6 l+ J        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
- @; x; w0 e7 w. [1 m: Q& o    // 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
' g) z" y7 @. ^* Y    // list from timestep to timestep
6 y; D2 Y. x, Z2 D  N1 J2 f        
/ Y. T! T0 t% k3 x! `    // By default, all `createActionForEach' modelActions have
/ Z/ O& I) p7 B. h3 k! f& e: d    // 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).
   
9 L$ m( l5 Q* \    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
; }2 b. g6 B% H; u: q        (heat, new Selector (heat.getClass (), "stepRule", false));
# E. z. `# i) Y, ]& r2 I    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
- A( T% P  g# X0 v0 Z/ V1 |) s
! {: k) y: q& E; Y! U. O1 h; W1 a    try {
$ I( a- O2 }  k5 ?/ G! p4 b      Heatbug proto = (Heatbug) heatbugList.get (0);
  ~$ x+ z/ E2 h5 m      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
6 k0 [8 e# Y  X0 R. N: l         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
4 n; d0 l, A! n& p6 Z      e.printStackTrace (System.err);
$ U" ^* ^2 t& ]" ~( S    }
! s9 }, D7 j6 v, A* ?   
    syncUpdateOrder ();
' j; t$ t- _# V; Z0 r$ Q. D1 r1 z9 w
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
# n) h* z- [; ]0 C; |, K! T. C' c      System.err.println("Exception updateLattice: " + e.getMessage ());
% z3 M+ |: _; X" m8 G$ 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
& ]! @7 C1 S$ V; I( H8 Q4 t    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
9 Z9 S7 D, Z# Q0 w2 P    // the beginning of the loop.
# z) S7 I( \) Z% P
    // This is a simple schedule, with only one action that is
; ]* s0 Z$ R% ~+ G    // just repeated every time. See jmousetrap for more
& u# v0 n5 e# q7 G9 l    // complicated schedules.
6 R: r* A4 ?4 h  
3 f3 [9 Y: k: {& O4 x; p* _) L    modelSchedule = new ScheduleImpl (getZone (), 1);
) h7 t; l  G- ]9 ~# g. |    modelSchedule.at$createAction (0, modelActions);
        
4 x  k: @" @. D    return this;
  }