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：
% H$ n& z) y3 f) }
/ ~' X0 n( h( t! |  E  P public Object buildActions () {
9 j4 h7 [) |' q6 m# I  x, z7 i    super.buildActions();
) V! J! \8 j+ F. B/ ]: v3 v   
    // Create the list of simulation actions. We put these in
1 H" L2 v0 ]' d5 |" x* C    // 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
    // called <foo>". You can send a message To a particular
( V" D+ @4 w' [    // object, or ForEach object in a collection.
* u. W6 `1 S2 B% [5 j4 d        
    // Note we update the heatspace in two phases: first run
5 i6 U  V2 H# N4 H0 `3 F    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
% B4 Y/ R+ x1 K0 N        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
6 b  h" \7 C$ X' T- h8 H; H    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
8 I4 T. [. y  p, `/ N9 M    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
, q+ o" f3 e+ b& t. S5 l3 }$ l' h    // identical (assuming the list order is not changed
$ b% _: Y# q) [- i) P4 r/ p" z    // indirectly by some other process).
   
" a& o3 E, [3 D; W3 v    modelActions = new ActionGroupImpl (getZone ());
7 C6 }8 {& Q  |7 Z, E8 P$ o5 u
    try {
      modelActions.createActionTo$message
/ B# `7 B: z+ u) e        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
- |: u9 a$ @0 M2 W' c      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

0 L7 I3 a0 _' m: Y9 ~    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
2 ?5 C7 d# G, Q3 T1 J- j* V0 o( M1 a      Selector sel =
+ ]5 H" S) H/ G3 `2 M4 k        new Selector (proto.getClass (), "heatbugStep", false);
' a+ u3 X5 m9 Z& i$ \      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
0 A7 `5 H. M6 ^9 P- F                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
3 k# o9 C4 n0 B8 A  f; O    syncUpdateOrder ();

    try {
* c8 \6 ?( S3 J# W      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
! f4 I* e. @8 ]- }( y6 h9 b2 J! d    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
# T# R% u8 S1 F- y! A0 y5 c+ Y9 T    }
        
% g$ z2 |5 J5 W# T, }; I    // Then we create a schedule that executes the
+ b2 T9 N8 B0 F8 ^, L    // modelActions. modelActions is an ActionGroup, by itself it
! h* H3 c" h  w5 |9 S    // has no notion of time. In order to have it executed in
; P" x9 j# d0 f3 J    // time, we create a Schedule that says to use the
; y$ o% v2 z; q. g# ^) Y6 q4 G7 {/ y    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
) ^: z) Z9 \8 y& C1 ?/ z    // time step.  The action is executed at time 0 relative to
* I6 o; p$ H% ]4 B0 A+ c9 e    // the beginning of the loop.

( P' d$ x" _& p9 z1 H8 X0 J    // This is a simple schedule, with only one action that is
9 T" V! X( Q0 w+ T    // just repeated every time. See jmousetrap for more
    // complicated schedules.
5 Z+ ~( h4 I$ R% V. ^9 Z$ [  
    modelSchedule = new ScheduleImpl (getZone (), 1);
2 U! K& F+ d% v8 x5 _    modelSchedule.at$createAction (0, modelActions);
! k7 d) j- @! r( H        
& d$ j* }  ^5 y1 v7 _    return this;
! l* n$ s( f8 a' x. J$ Y  Z  }