Re: [Java-player-users] Problems with laserinterface

[kevinl <liu...@gm...>]

Hi Skuld,
Thank you for your advice, I call runThreaded(-1,-1) before my code and I
can get the data now. And I'm sorry to reply your message so late.  And I am
confused why the fuction of runThreaded(-1,-1) will call an equivalent of
Read. Could you tell me why?

Thanks a lot,
kevin


Skuld wrote:
> 
> What is your version of JavaClient?
> 
> I don't work a lot on JavaClient, but I know that you have to call
> (directly or not)
> a function whose name is Read() (PlayerClient in the c++ native library),
> in order to retrieve data from
> Player/Stage, to fill up fields of your structure, and then you can reach
> data by
> functions like getRanges().
> So your first call of getRanges, "lsri.getData().getRanges();", can't fill
> these fields. It's useless.
> Maybe you have to call readAll() (of the class PlayerClient in javaClient)
> if you're not in threaded
> mode, or call runThreaded(0,0) if you implemented the Runnable interface.
> Those functions will call
> an equivalent of Read.
> I guess that "isDataReady" doesn't ask a reading from Player/Stage, but
> only check if, in the most recent data retrieved, there is data about
> laser. But you
> still have to retrieve it.
> 
> If it doesn't work, check your "robot" creation. Maybe it's your
> nullpointer error' source.
> 
> Do you know the name of the function which cause the error?
> 
> 
> kevinl wrote:
>> 
>> Hi all,
>> I don't know how to use the laserInterface, so I run the following code
>> for a try:
>> lsri = robot.requestInterfaceLaser (0, PlayerConstants.PLAYER_OPEN_MODE);
>> while(lsri.isDataReady());
>> 	lnum=lsri.getData().getRanges_count();
>> 	lsri.getData().getRanges();
>> 	ldata=lsri.getData().getRanges();
>> 
>> I get the error of "NullPointerException". Could you advise me on how to
>> use the laserInterface? And I am confused with the method "public void
>> readData(PlayerMsgHdr header)" , how can I get a PlayerMsgHdr variable?
>> 
>> Thanks a lot,
>> kevin.
>> 
>> 
> 
> 

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