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：

7 T6 [  U0 F9 H8 t public Object buildActions () {
    super.buildActions();
. ?/ z/ v/ w; a. A6 r# o   
! R+ U2 a# L2 }3 {3 h: U    // Create the list of simulation actions. We put these in
  A1 u1 {7 b9 ^0 g    // 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
; h! K3 |; g# t3 U* c! @    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
$ {3 I; T: ^- O7 k% S$ \        
" s& `) n# J/ \+ }% m, k    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
7 K, G1 K6 [; |3 _7 [        
4 s4 G! l1 g, P2 G! S8 `    // Note also, that with the additional
0 T  ]- A7 |. F1 r  \0 J    // `randomizeHeatbugUpdateOrder' Boolean flag we can
6 U! s5 b# L" u. N' U7 V' W    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
6 J* F4 y4 Q# H    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
% J- @) B/ M! V8 C3 Z    // By default, all `createActionForEach' modelActions have
/ E+ O( K" C0 [. E. g( `! N    // a default order of `Sequential', which means that the
, J  |9 s) K7 y' T: {) Y* }! H& i    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
  q- i8 W: i; p/ X+ B
    try {
, B0 s- q2 E6 Q      modelActions.createActionTo$message
& U; j- \1 a) r8 }( a$ f3 ]9 ~        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
. f9 q  Z3 |# K6 _% }' \    }
) g' d: H7 h+ M. Z
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
" S6 I5 Q2 t9 k' B; c  ?        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
6 M: k; n' N6 @- r9 Z        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
6 \- P3 D; Y1 }5 z/ K
3 `7 j) h- B) J& f6 p# t    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
! ^, g4 J) ^% Y1 l& i; J1 `    } catch (Exception e) {
$ M, X$ M  e- q, T; q      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
  o- h, L0 o$ D5 V, v3 {        
, ~" E! V' A1 y' o6 D4 `    // 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
7 M$ g/ A. Q1 h/ ?, {) s  |    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
: X# F) D; b  a, s    // schedule has a repeat interval of 1, it will loop every
9 `6 s5 U: g, I# g9 `- e    // time step.  The action is executed at time 0 relative to
# ~" f5 V0 U* k* V$ @2 u; E: G% j! ]    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
1 E% L6 I# Q1 {! W6 q+ l, H) {    // just repeated every time. See jmousetrap for more
    // complicated schedules.
) p! _5 n% |' v- {4 z$ v  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
8 \( l) J1 s% y" [+ l* m0 O/ u- S        
* ?" C. T9 P# _    return this;
  }