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：

public Object buildActions () {
+ X# @% @8 T: M: G1 t  _    super.buildActions();
   
" e9 b9 K) [2 q; ~" F5 f    // 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
, T& d" o; u# m% E6 S* @    // called <foo>". You can send a message To a particular
& M: M3 u$ E7 v7 \. ~+ }8 w    // object, or ForEach object in a collection.
4 B" f3 i6 ]; u        
; R3 H1 u' \7 o5 o4 I    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
        
5 N" N9 I; \8 L8 _) N, @. K; T    // Note also, that with the additional
, `0 J  w4 g9 C- t) X0 j    // `randomizeHeatbugUpdateOrder' Boolean flag we can
. y! L& {, S8 d# G. n    // 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
; o- G" l4 A2 v+ F/ a    // list from timestep to timestep
" }! a" G' L$ v        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
  g8 B0 g$ Q$ W5 u1 [" U' ]. Y3 F    // indirectly by some other process).
8 P; n4 c- ^1 l. r8 ~! _$ _* F   
' n+ l3 f& N7 C    modelActions = new ActionGroupImpl (getZone ());
3 `7 s; i5 E0 |) s
    try {
" _4 B7 @) {2 i2 @& T      modelActions.createActionTo$message
. S, C; S/ S/ V; H: o        (heat, new Selector (heat.getClass (), "stepRule", false));
  m) c! H: C& F. x5 U3 x    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
/ i( q+ {6 X; @/ o( O+ }% k    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
, e. R# h9 @; b5 w: ]        modelActions.createFActionForEachHomogeneous$call
( a' Q) I$ C: K0 H; n# ?- F5 p        (heatbugList,
" \2 p$ _1 x7 g4 c- v* X/ c         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
) K: R: D! z# y) Z, {6 O    } catch (Exception e) {
      e.printStackTrace (System.err);
. g; S8 E  h$ u0 n+ h    }
   
9 v9 E4 M: m) l, U/ s6 S; U  q) W    syncUpdateOrder ();
# O4 c8 }) {, f$ F2 _. m% G; {
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
- k% e0 n8 a! V- {7 f5 ?    }
        
    // 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
1 X/ c, B/ Z/ r* U! e    // 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
5 @8 I' i) W+ L) g    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
- c7 ~* Z. W$ O
* S) o- W: s( L# R    // This is a simple schedule, with only one action that is
5 E0 T5 D8 u1 p- Z1 R* _0 N    // just repeated every time. See jmousetrap for more
    // complicated schedules.
" i: S2 t- X: s) S$ n  W# u% }  
    modelSchedule = new ScheduleImpl (getZone (), 1);
6 P, l  M$ c( N+ e0 h+ `5 i  f  m    modelSchedule.at$createAction (0, modelActions);
        
& P9 W5 S3 ?6 i( Q) c+ Q    return this;
  }