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：
! k3 t, q2 i4 I1 m4 a9 e8 C* Z
3 W7 L9 ]" Z# O. L5 r public Object buildActions () {
    super.buildActions();
   
# A: j% O0 S3 W; k" ~    // Create the list of simulation actions. We put these in
; u! p! ]& y9 I5 u; N    // 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
8 h) i; \3 B4 z    // object, or ForEach object in a collection.
$ W0 S  P$ q) t7 C        
  {5 w' K0 N$ F    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
6 i3 W1 B& [! d" X* v% Y    // changes the heatbugs have made. The ordering here is
    // significant!
0 {- q, f6 `+ ~4 c        
! I$ J2 c7 N, q3 \! F    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
3 j! ^% y9 n! @( w7 {    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
* Z$ u4 C9 h2 }; C5 ~    // list from timestep to timestep
& G# r0 s2 A% |8 t9 a4 ?. {        
    // By default, all `createActionForEach' modelActions have
" \2 [$ @+ w5 V/ z    // a default order of `Sequential', which means that the
' @" R6 t. G7 [3 [4 ?6 ^3 B- ]9 }    // order of iteration through the `heatbugList' will be
& j' W& J8 |& |- G. R0 ]$ D$ j    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
* M# N% O! H4 o1 Y
    try {
" F: h& r# Q6 ^5 L* h      modelActions.createActionTo$message
  k4 Z! H' {6 R: p        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
# D( F; `; P9 g      System.err.println ("Exception stepRule: " + e.getMessage ());
$ p/ Z1 T4 }8 y. @0 u% W/ I0 K    }
$ P" Q9 i9 w7 R7 O% c4 b" d: Z5 E
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
5 }0 L- V$ F" K) r( t: w  Z      Selector sel =
; H+ i; d+ A( L. C7 H  i        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
! g5 c2 N; y! N         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
/ P" s7 e6 d0 ?: t! p9 e( }0 \* s   
6 \- W# v9 |% t4 P" A3 M. ]; d    syncUpdateOrder ();

    try {
6 t$ r2 h( H& ~$ N! y2 D      modelActions.createActionTo$message
2 q3 E- t1 R# ]; n6 D! u) B        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
% l2 J# u2 \) e3 E# ?% q/ C2 v. i) a5 c& O      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
! c1 [# L+ n! e$ l/ B- c  m+ _. S' h    // 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
    // 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.
; T8 p1 M5 T- T% s% }; P0 }# ~! @
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
5 a9 [; _& K2 v( T' Q/ m    modelSchedule = new ScheduleImpl (getZone (), 1);
  X8 N, x! H, A* V    modelSchedule.at$createAction (0, modelActions);
        
3 S- y6 X5 ?. G2 e    return this;
: ^2 [9 w& Z6 W  }