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problem with geometry_msgs.Twist on Android

asked 2012-05-15 07:19:29 -0500

Artjom gravatar image

After looking at the in the Honeycomb example I tried to do similar thing on Gingerbread, however I was getting NullPointerException when trying to access currentVelocityCommand variable which is of type geometry_msgs.Twist.

Looking at the code of it turns it's an interface. To implement Twist I also need to implement Vector3, and I'm now stuck with toRawMessage() method.

This is probably the wrong path and surely I'm missing something obvious.

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answered 2012-05-16 03:34:57 -0500

Artjom gravatar image

Turned out I was on the wrong path. Everything is in the documentation. All I had to do was just use the MessageFactory and create the message of the Twist type. Everything works as expected now.

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You should use the convenience methods like Publisher.newMessage() where possible.

damonkohler gravatar image damonkohler  ( 2012-05-21 06:05:10 -0500 )edit

Hi Artjom, I am also having the same null pointer exception problem you had when using Twist. In fact, the null pointer exception occurs even with the sample code "android_tutorial_teleop" provided with android_core. Do you mind letting me know what you did to solve the problem successfully? Thanks.

Tuan gravatar image Tuan  ( 2012-06-02 04:05:53 -0500 )edit

answered 2012-09-23 04:11:48 -0500

JMata gravatar image

Hi, i have the same problem as Tuan. I am running the "android_tutorial_teleop" provided with android_core and having a null pointer exception problem with "currentVelocityCommand" variable. Could anyone help me? Thanks!

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Asked: 2012-05-15 07:19:29 -0500

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Last updated: Sep 23 '12