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：
# g; ]4 b! I, d8 D1 D+ `, G. r, x
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
2 v3 f+ j3 r! {9 T) e4 }    // executed in a specific order, but these steps should
+ j* |( k% K) ]    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
4 C- E4 k6 c' d' [- ]2 b    // object, or ForEach object in a collection.
        
: A' M: X( \! W; R1 E3 [. n* ?    // Note we update the heatspace in two phases: first run
( z3 w  y: _, }8 }! W9 a, s8 o    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
        
. }5 b; Z, T! F& s; L& f! T    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
0 g; ?' ?/ ?% ]    // randomize the order in which the bugs actually run
4 Z$ m) |$ T* E, o2 d    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
) S4 o, C) A7 K4 A8 H    // list from timestep to timestep
. o; t7 N3 W, a5 b. c. A9 M        
# ~" O, s$ W8 \6 |% y! ?# I8 [    // By default, all `createActionForEach' modelActions have
/ Z% W9 O5 Z( b& ^7 N    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
: L& p) Y( p4 X: t3 Z% P2 ?    // identical (assuming the list order is not changed
8 {1 R. B, w8 b5 W8 F% U! N! Z    // indirectly by some other process).
, l5 h' D: O5 z. }   
1 B$ x4 N7 ]3 ~4 b$ m7 n: J4 R* z$ s3 ~    modelActions = new ActionGroupImpl (getZone ());

    try {
' ?8 G0 ]% G; u" \2 N      modelActions.createActionTo$message
3 A0 V" T; z! d, d  u6 ]# |        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
  E0 k4 L- x2 h
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
$ R$ M, O" Z! h3 n3 G6 T( L. [/ ]        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
5 u0 h8 f2 z: }         new FCallImpl (this, proto, sel,
! t+ V  E* y/ B! }' y! b0 z2 E                        new FArgumentsImpl (this, sel)));
0 @$ _# Y% t  |2 j    } catch (Exception e) {
      e.printStackTrace (System.err);
8 }6 C( p. z& V# n& U    }
   
9 M# @! A  |+ e& c+ s    syncUpdateOrder ();
' f: O* w* w2 C9 j- r1 b1 V( J
    try {
      modelActions.createActionTo$message
( p3 I% C! b1 s& T        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
3 |, R) B; v  G' {& T. e      System.err.println("Exception updateLattice: " + e.getMessage ());
" E$ L: }" Q$ M- x1 f4 t    }
        
  E- s: f1 U. G9 c    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
$ |8 [9 j( T1 R, d    // 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
    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
! z5 ]- t1 Y/ O7 M3 ?1 I
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
3 ~: }2 o  P0 d% K: S  
. ?; g0 O/ D% F' ~( v0 Z    modelSchedule = new ScheduleImpl (getZone (), 1);
% l0 C' n2 R2 t! t    modelSchedule.at$createAction (0, modelActions);
- K  L- T& M) a  x- r3 Z# d        
    return this;
  }