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：
6 N' X* V. K) N' b
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
  A0 D! l  }. }* a5 r    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
9 T6 S  s# i7 S+ U# t' A# o  W, _7 ?    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
$ h1 m+ ?+ N+ s; c0 ]    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
8 K0 f. U1 T. d" }' Z( N: k    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
+ e4 f6 _9 @2 r; X* F4 M) D    // their step rule.  This has the effect of removing any
6 L( s4 v2 c* x2 S% Q0 `# g6 q    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
8 c! W/ Z/ _8 Q. @# ^, [! ]    // By default, all `createActionForEach' modelActions have
+ ?8 c) I0 |7 h  [: Z4 ^    // a default order of `Sequential', which means that the
) T! J6 m! h3 [! f7 I( \) i& }    // order of iteration through the `heatbugList' will be
, Z" v2 ?( z% u4 u& ~2 d    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
4 I! }" q) N, J; l    modelActions = new ActionGroupImpl (getZone ());
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    try {
+ B. ]" B" \6 d( l" [      modelActions.createActionTo$message
; N: H  ~4 j4 U# l        (heat, new Selector (heat.getClass (), "stepRule", false));
9 `# A  G4 l0 k  [7 ^    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
, {5 ~0 v8 s" x    }

    try {
: U5 C( ^8 X' h# y7 R& @      Heatbug proto = (Heatbug) heatbugList.get (0);
8 ?+ Q) t/ b6 g% e( v0 P      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
) l9 v  v3 w/ B: N0 w  t; t        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
3 ?; R& [  @8 ]  p2 s         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();

    try {
4 ]% A+ ?, v. r9 F! e9 x      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
* W5 {2 S2 D7 a, g# O; Q+ k    } catch (Exception e) {
' g* W0 }1 n; q      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
7 u- T$ y$ _9 z, ]    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
: Y# e  E" D& e: R, h& k    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
( ?: f5 ?1 m% p4 t    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
# g* c! W8 B( s" U$ x    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

, S0 ^& y$ x& ^* H( C+ ]) }    // This is a simple schedule, with only one action that is
/ a; \# Y, L0 d" k' ~5 ], t    // just repeated every time. See jmousetrap for more
* \, e) c; a! [& {7 \& A# [    // complicated schedules.
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# O+ Y* S, \: r    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
4 w' h* H  K5 w% A4 D5 b2 A+ T! l9 e9 p        
    return this;
( L! U3 b; P$ v  }