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：

( {) D! N+ K' M* n! q3 ? public Object buildActions () {
+ L2 D5 ~1 L% i6 |+ Y    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // 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
! [- O/ K. z  N( Y    // called <foo>". You can send a message To a particular
; ?" X5 X) p" s* h* K; H2 K    // object, or ForEach object in a collection.
' y! ^7 b. e. u" R4 q) {        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
- r! @; m, H  @: v    // changes the heatbugs have made. The ordering here is
6 P* j1 P/ {; a4 B8 i" p4 q, }$ W7 }    // significant!
        
    // Note also, that with the additional
0 x2 Z; U6 q' }( W    // `randomizeHeatbugUpdateOrder' Boolean flag we can
% c" }' a0 A: g3 b" J    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
$ j8 ^4 P0 t6 o( ^# ]* Z* p    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
# t$ A  ^. ?0 t5 R3 |3 v( F        
4 Q" `0 m/ I" l    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
, j+ h+ J: Y) r4 P5 v  y; P9 ?    // identical (assuming the list order is not changed
+ i6 v6 T7 w' P: ^3 D    // indirectly by some other process).
; w* c5 \4 g/ m4 l# ^2 \   
    modelActions = new ActionGroupImpl (getZone ());
+ u8 ?2 a: u5 z/ ^
    try {
      modelActions.createActionTo$message
: ?5 t9 l6 d- \# e" O1 ]        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
) V9 k7 D3 x4 J, D    }

3 j" S" }3 t7 b6 R. {% e/ a  W4 _    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
; O# c$ ?, C6 v" [$ M* M      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
! ?4 T% P6 q4 L2 G6 U1 U      actionForEach =
; _. Z5 ]2 ]! @+ X! v# L        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
! v2 y# j2 L: a                        new FArgumentsImpl (this, sel)));
8 E, m8 l$ a& S5 w    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
$ a6 d& `- P1 e: J$ }9 \   
% {+ z. ^" U- p" I8 q2 `2 v2 D    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
. C* h* ~8 N/ ?9 v: R7 O3 n        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
9 G1 Z3 M% Q' T! w6 b2 l( y    }
        
* E; r$ ?; z2 X" Q/ F& S4 b    // 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
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
* Q  S, s. j- N; `/ N/ Y0 ^" ^, x    // schedule has a repeat interval of 1, it will loop every
0 s, v. D9 N# w1 z/ A# ?    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

' t. B6 p+ H- h: U- {    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
: V/ }: p+ o1 r1 P    // complicated schedules.
* T1 t* n7 _8 q  
' }0 O$ U% e6 ?1 T  d7 R$ T    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
5 K" `" L9 A% \2 d* N    return this;
  }