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();
2 ~/ G$ i, }& x" i$ q0 v- L   
    // Create the list of simulation actions. We put these in
6 b' ~* a- m+ U) \& t% B( `8 C    // an action group, because we want these actions to be
3 h, M( [, Q) k& A- ~    // executed in a specific order, but these steps should
0 T: b" ]+ c1 i: ^: J4 w) W# ?    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
8 v4 x9 I9 u# t% P7 C9 V+ z. L    // object, or ForEach object in a collection.
        
& u. ~4 l+ f% u5 Z% I    // Note we update the heatspace in two phases: first run
: j4 X2 _$ h2 \    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
  Z* o4 s7 \- T/ S. O7 o  l8 D$ _    // significant!
- h+ P( |' h/ Q$ A        
& |) \- D7 P0 Y6 I; f9 }. t    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
6 h( n: _) o9 O1 p0 `# ?! o    // their step rule.  This has the effect of removing any
! y1 T; k  K! s! @3 |5 [    // systematic bias in the iteration throught the heatbug
' _8 N8 q+ W6 E2 i" b    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
2 r7 A* }0 n$ ^: _( v- |    // a default order of `Sequential', which means that the
: p# Y) Z8 ?1 S2 @5 z4 a* d' l    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
0 d$ b  N$ @3 f. N9 i   
    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
4 A" G4 I3 k. ]( C& J6 T    }
6 C. D* _- X" Z0 G) h& T
# ]0 j2 {; }( M) ?% Y; q( R9 K    try {
5 r* y4 U  m4 h' P5 [4 O      Heatbug proto = (Heatbug) heatbugList.get (0);
) y; W* g7 y' }      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
0 a8 w. W0 ~; Q( J/ O        modelActions.createFActionForEachHomogeneous$call
/ b) Z4 m4 E$ ^- R0 D2 q        (heatbugList,
         new FCallImpl (this, proto, sel,
+ O. U2 q, C4 m) }6 L                        new FArgumentsImpl (this, sel)));
% l3 X/ s' S! d2 Z( k) |    } catch (Exception e) {
      e.printStackTrace (System.err);
3 c' p6 N2 g+ S( t6 x8 x    }
7 b5 q/ h/ N; {+ y% d$ e8 E$ {   
: }9 X# m6 Z7 T    syncUpdateOrder ();
; F7 M9 U" m/ \5 W7 X
0 h& S5 F; q( e; h! ?1 J: L/ b    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
+ M0 }6 ?+ V' X+ b: y0 p: A    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
/ P" e3 [" @8 J. K        
    // Then we create a schedule that executes the
1 o  ^3 g9 J" C1 n    // modelActions. modelActions is an ActionGroup, by itself it
& |# r2 w& Q, }- a$ {: Z    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
# X. i5 x3 o' A    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
* X$ a- p+ F0 q4 p/ \    // time step.  The action is executed at time 0 relative to
- W' o/ F- J/ U' _    // the beginning of the loop.
+ X8 f; }+ K- V" v0 M' `0 E4 \0 S
    // This is a simple schedule, with only one action that is
. l" Y# o5 e5 Y0 \# B7 V    // just repeated every time. See jmousetrap for more
& X: g; V8 b4 D: z3 P    // complicated schedules.
  
3 I5 Y; m" S2 ^! r; I4 @    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
0 p/ O! Y0 ]9 U% w7 Y/ @    return this;
! {9 q8 D* M- n+ M' A, }  }