0.6.0-alpha release

This is where you talk about the EV3 software itself, installation issues, and programming talk.

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Re: 0.6.0-alpha release

Postby marcin.kasinski » Thu Feb 20, 2014 8:56 pm

Wifi Issue 1:

First time I choose wifi from menu (just after installing sd) I got message "no access points".
Second time I choose wifi from menu works ok. I can see wifi list

Wifi Issue 2:

When I choose wifi access point , set password and choose OK brick hangs. After "hard" restarting everything works fine. I can see IP from wifi.
Regards.
Marcin Kasiński
http://itzone.com.pl
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Re: 0.6.0-alpha release

Postby roger » Fri Feb 21, 2014 12:06 am

Hi Marcin,
I have had the same experience, but it took more than 2 attempts before any access points appeared. Also, a hard restart was required before the connection was actually made. Perhaps the wiki could mention these difficulties.
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Re: 0.6.0-alpha release

Postby epascual » Sat Feb 22, 2014 2:40 pm

Hi everybody,

Thanks a lot to the leJOS team for the 0.6.0 version, and the cleaning done at classes organisation level. It's a real pleasure to work with this environment, and I'm happily using it with young students in the context of my associative activities.

Just a question, since I could not checked it by myself. I have the feeling that Java programs take longer time to start on the EV3 than it was used to be on the NXT. It this the consequence of using Oracle JVM now in replacement of the tiny one for the NXT ?

Best regards.
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Re: 0.6.0-alpha release

Postby lawrie » Sat Feb 22, 2014 3:07 pm

Yes, a very large number of separate classes are loaded when using the Oracle VM. On the NXT, a single linked binary was loaded.
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Re: 0.6.0-alpha release

Postby epascual » Sat Feb 22, 2014 3:17 pm

And I guess there is nothing that can be done to avoid this :/
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Re: 0.6.0-alpha release

Postby gloomyandy » Sat Feb 22, 2014 8:13 pm

No real effort has been made to optimize program load time so far. However in general with a fully featured JVM and Java system there are additional costs and one of those is the much larger number of classes that end up being loaded. There may be things that can be done to improve this to some degree, but I suspect it will always be slower than on the NXT.
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Re: 0.6.0-alpha release

Postby epascual » Sat Feb 22, 2014 10:47 pm

Thanks for the precision.

Excuse me if the question sounds stupid, but why has the "old" Java environment been replaced by Oracles's one ? The leJOS class ecosystem was already working quite well with this version.
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Re: 0.6.0-alpha release

Postby skoehler » Sat Feb 22, 2014 11:47 pm

epascual wrote:Thanks for the precision.

Excuse me if the question sounds stupid, but why has the "old" Java environment been replaced by Oracles's one ? The leJOS class ecosystem was already working quite well with this version.

The "old" Java environment consisted of a self written JVM, that was designed for very confined environment (e.g. 64KB RAM, embedded system without an OS) and the EV3 is basically a Linux system with 64MB, enough to run a proper JVM. Also, if you're using the NXT version of java.lang.String, you'll notice that some stuff is missing, like the split() method. That's simply because in addition to rewriting a JVM from scratch, we also had to write a basic java runtime library from scratch. On the EV3, you can finally use a fully fledged java runtime.
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Re: 0.6.0-alpha release

Postby epascual » Sun Feb 23, 2014 12:04 am

OK, I see. I suppose that making the home-made NXT targeted Java environment run on the EV3 was too much work compared to migrate to a ready to use JVM and environment.

This will not be that easy to explain to the kids who asked me why programs are now longer to start, although the EV3 has a far more powerful engine inside than the NXT ;)
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Re: 0.6.0-alpha release

Postby skoehler » Sun Feb 23, 2014 12:07 am

epascual wrote:OK, I see. I suppose that making the home-made NXT targeted Java environment run on the EV3 was too much work compared to migrate to a ready to use JVM and environment.
It would be possible. But it would also come with a caveat: namely that many features of modern JVMs would not be available (unless we implement them, which would be a really big amount of work) such as: object serialization, RMI, dynamic class loading, etc.

epascual wrote:This will not be that easy to explain to the kids who asked me why programs are now longer to start, although the EV3 has a far more powerful engine inside than the NXT ;)
After the programs have started, they actually run faster. The old JVM only interpreted bytecode. Oracle's JVM actually compiled the bytecode to machine code.
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Re: 0.6.0-alpha release

Postby epascual » Sun Feb 23, 2014 12:21 am

skoehler wrote:After the programs have started, they actually run faster. The old JVM only interpreted bytecode. Oracle's JVM actually compiled the bytecode to machine code.
This is a very good point.

I'll try to convince them to experiment by themselves with comparative benchmarks. It would be a very educational practice.
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Re: 0.6.0-alpha release

Postby wiso » Thu Mar 06, 2014 5:42 pm

Hello!
How can I run the programs of the samples folder with ssh? I use Putty program and I would execute the programs with extension .jar of my EV3.

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Re: 0.6.0-alpha release

Postby epascual » Thu Mar 06, 2014 5:47 pm

Hi,

You just have to go to their directory (/root/lejos/samples if I remember well - I have no EV3 at hand at this moment) and enter the command :
Code: Select all
jrun -cp <jar-file-name> <main-class-qualified-name>
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Re: 0.6.0-alpha release

Postby lawrie » Fri Mar 07, 2014 6:50 pm

The directory is /home/root/lejos/samples and you only need to do:

Code: Select all
jrun -jar <jar-file>


as the main class name is in the manifest of the jar file.
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Re: 0.6.0-alpha release

Postby wiso » Tue Mar 11, 2014 4:05 pm

Hi,
I did that, but I had this answer "/bin/jrun: exec: line 11: /home/root/lejos/ejre*/bin/java: not found" . Do I have to install on the EV3 something of Java??

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