Re: [Java-player-users] Player/stage java

[Jorge S. S. <jsa...@gm...>]

Good morning.
Here you have a short "how to", courtesy of Elmer Alexis (thank you, Elmer!)
We will try to launch SpaceWandererExample example


The first step is to be installed:

Player 2.0.5
Stage 2.0

then you have to install version 2.0.1 of JavaClient, for this must
have JDK installed, in my case I have installed version 6.

I have not tested the javaclient examples with javaclient3. I´ll do that
on the following weeks, posting a new version of the examples on the
case there are incompatibilities. By the moment, it will be safer if you
use player/stage/javaclient 2

choose any stage configuration file (that launch player with simulator
Stage used as a plugin)

when trying to run the examples found several errors:

player: error while loading shared libraries: libplayerdrivers.so.2:
cannot open shared object file: No such file or directory

This first error is given by player, player needs to find the
libraries to execute, error is resolved with:

export LD_LIBRARY_PATH=/usr/local/lib

COMPILE EXAMPLES:
other error is to try to compile the program with javac:
by typing: $ javac SpaceWandererExample.java

The error is:

SpaceWandererExample.java:26: package javaclient2 does not exist
import javaclient2.PlayerClient;
                 ^
SpaceWandererExample.java:27: package javaclient2 does not exist
import javaclient2.PlayerException;
                 ^
SpaceWandererExample.java:28: package javaclient2 does not exist
import javaclient2.Position2DInterface;
                 ^
SpaceWandererExample.java:29: package javaclient2 does not exist
import javaclient2.SonarInterface;
                 ^
SpaceWandererExample.java:30: package javaclient2.structures does not exist
import javaclient2.structures.PlayerConstants;
                            ^
SpaceWandererExample.java:129: cannot find symbol
symbol  : class SonarInterface
location: class SpaceWandererExample
       public static String decodeSonars (SonarInterface soni) {
                                          ^
SpaceWandererExample.java:54: cannot find symbol
symbol  : class PlayerClient
location: class SpaceWandererExample
               PlayerClient        robot = null;
               ^
SpaceWandererExample.java:55: cannot find symbol
symbol  : class Position2DInterface
location: class SpaceWandererExample
               Position2DInterface posi  = null;
               ^
SpaceWandererExample.java:56: cannot find symbol
symbol  : class SonarInterface
location: class SpaceWandererExample
               SonarInterface      soni  = null;
               ^
SpaceWandererExample.java:60: cannot find symbol
symbol  : class PlayerClient
location: class SpaceWandererExample
                       robot  = new PlayerClient ("localhost", 6665);
                                    ^
SpaceWandererExample.java:61: cannot find symbol
symbol  : variable PlayerConstants
location: class SpaceWandererExample
                       posi = robot.requestInterfacePosition2D (0,
PlayerConstants.PLAYER_OPEN_MODE);
                                                                   ^
SpaceWandererExample.java:62: cannot find symbol
symbol  : variable PlayerConstants
location: class SpaceWandererExample
                       soni = robot.requestInterfaceSonar      (0,
PlayerConstants.PLAYER_OPEN_MODE);
                                                                   ^
SpaceWandererExample.java:63: cannot find symbol
symbol  : class PlayerException
location: class SpaceWandererExample
               } catch (PlayerException e) {
                        ^
13 errors

to resolve this, use the path where are stored the clasess of JavaClient:

$ export CLASSPATH=”$CLASSPATH:/home/elmerlab/Documentos/Javaclient2-2.0.1/classes:.”

This step solves the problem and generates the .class using the javac.
After trying to run the file with the command:

$ java SpaceWandererExample

appears a new error:

Exception in thread "main" java.lang.NoClassDefFoundError: SpaceWandererExample
Caused by: java.lang.ClassNotFoundException: SpaceWandererExample
       at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
       at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: SpaceWandererExample. Program will exit.

This is why you need the files .jar, this is corrected using the following path:

export CLASSPATH=”$CLASSPATH:/home/elmerlab/Documentos/Javaclient2-2.0.1/jars/javaclient.jar:.”


I hope this help. Please tell me if you have further problems.


> Dear Developer,
> can you tell me after installing the Player/stage javaclient and the player
> also how to run the examples which are the main class to run a simulation
> and how and where to write world and configuration files?? there are 2 test
> examples on your web page but which class in the client is responsible to
> run them thanks in advance

> --
> Bests
> Khaluf