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：
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public Object buildActions () {
    super.buildActions();
# g% D5 P' q# [* y- ^6 ^   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
. E( \$ ]0 I2 L% Z) a+ h    // 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
    // object, or ForEach object in a collection.
+ ~" n; x* f, v& m6 j9 A! o        
    // Note we update the heatspace in two phases: first run
# B1 y7 f9 m! B0 e+ F- k+ r2 k! W    // diffusion, then run "updateWorld" to actually enact the
3 b- a7 Z) ^' a% _    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
* P2 S; I+ i2 l& p/ P    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
# K6 @/ U9 l- ?4 c. J# S1 F    // their step rule.  This has the effect of removing any
9 Y* d  m3 S3 b+ w2 w8 X    // systematic bias in the iteration throught the heatbug
- H8 ?6 @! v  B) i) Z% t) b/ C- \1 T    // list from timestep to timestep
        
5 A7 A# m7 ]+ T    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
4 F/ Q. m  X7 z8 a% W1 @7 C    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
: V2 X. R9 J8 o8 q$ [1 t. V0 F    // indirectly by some other process).
   
  `& I, p" i3 ^    modelActions = new ActionGroupImpl (getZone ());
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    try {
) H, L: ]1 ~; w2 p      modelActions.createActionTo$message
: y1 f7 N" I9 F$ D        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
- s8 p& s5 q  T1 P: a( h      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

0 H, |! Y0 v) G- u- R    try {
9 ~9 d1 @4 w/ B6 r, v8 S      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
$ o2 j/ D: `# r) H        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
  K- u) O1 g9 v' u1 i        (heatbugList,
2 |; n0 I, e  ]1 R( ], b+ H         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
# P: {5 Y) o3 U/ D& l9 F) j    } catch (Exception e) {
      e.printStackTrace (System.err);
3 h+ l! v- [3 ?) z1 t" [    }
5 d- b& h7 f; }$ r. R1 p  c8 j   
    syncUpdateOrder ();

    try {
1 v: t# j- d/ C$ I' K$ G6 H/ s9 ~      modelActions.createActionTo$message
/ A" l- j* L# a        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
! P! P, r4 Z0 F9 z6 [9 E" Y2 }( f    }
4 ~0 T. V3 j, O0 R* o- o        
    // Then we create a schedule that executes the
) K1 P9 Y/ W# T& b4 Z% _    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
' \* E3 }# g  P, k1 Q    // modelActions ActionGroup at particular times.  This
: F' z$ e) l' N. `    // schedule has a repeat interval of 1, it will loop every
! N" i* y) \: l# `9 ?. k$ l    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

0 Z1 I2 g/ j- \( l1 @9 Y, L9 l    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
/ ~7 o: U1 B8 A- {7 t- E3 z" ~& t    // complicated schedules.
9 G7 [1 G2 c" ~! {" b  
) l. M* K5 [# f. {    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }