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：

! C' B8 z" z2 {1 `& ]" R; w public Object buildActions () {
    super.buildActions();
9 k* G! ^7 m8 I6 y) M0 X* a' p0 {   
& |& ]0 c5 [1 W$ C) L    // Create the list of simulation actions. We put these in
3 ~% w1 `$ H4 E    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
+ I  z4 K5 t  r& F( {: D; d    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
* }! K3 y3 A, o! u# I" R- G    // Note we update the heatspace in two phases: first run
0 N1 o" R: E3 u; \- P    // diffusion, then run "updateWorld" to actually enact the
+ n" M! L- d  K2 K" J    // changes the heatbugs have made. The ordering here is
    // significant!
/ [5 ~( x5 H5 f1 [+ q; F        
5 c- I$ r3 T+ P! O    // Note also, that with the additional
' Y6 }! u- e& t, T+ F6 k    // `randomizeHeatbugUpdateOrder' Boolean flag we can
1 x, ]! ?' S# Z- m! D    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
4 y; R5 V3 N5 V. Q7 ?9 [    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
3 q0 K: m4 ~3 ~3 f    // By default, all `createActionForEach' modelActions have
' e& Q" @( ]* H1 e' J$ g9 }1 ?3 S    // 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).
  X6 y  \3 G9 y   
1 y9 O  D9 @& d1 S' j6 W    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
1 q, P$ F( X% u! I3 p        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
3 P1 T8 K8 B; I; q1 ^; L      System.err.println ("Exception stepRule: " + e.getMessage ());
& U: w6 s9 o+ b+ i, X" ?    }

    try {
& U5 I8 u6 S2 v1 G6 w9 N0 v      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
" ~3 V- a1 a7 |8 H1 ]) X) Q6 T) F        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
9 I1 s, |. p: i) t; W         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
2 v  A- B  p% @6 U6 I' |8 t' K    }
   
. w5 z8 }; |- Q2 C& D% {/ a+ U    syncUpdateOrder ();

# c4 x! m1 @& u8 w# s    try {
      modelActions.createActionTo$message
7 k; j, S# G# X2 K8 U# f1 p* U3 {        (heat, new Selector (heat.getClass (), "updateLattice", false));
" R0 n. O. r5 O( f    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
7 T9 u8 T8 Q, ]& ^' f0 ~    }
2 d( o4 b- x1 f# H6 {# W* f        
    // Then we create a schedule that executes the
. s% }" N) i* D3 ]! l  u* p    // 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
. @; k! S5 N/ i4 @* ~' p    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
" b5 O8 p! k" L( G8 @; {" j* _    // just repeated every time. See jmousetrap for more
& H: |0 d: |- ?2 Q  T. B    // complicated schedules.
  
8 J5 W  c9 \! k3 M2 C% T6 D    modelSchedule = new ScheduleImpl (getZone (), 1);
2 C$ _, D" c; A& j  c' t    modelSchedule.at$createAction (0, modelActions);
        
    return this;
) R* F. C! q! v! Q  S! j2 ]& o  }