Shall I move from C to Java?

[dick]

Hi everyone,

I am planning to learn Java.

Can I access HW registers in Java? Or can I call C function from Java
program?

Thanks.

 

[Tim Wescott]

Hi everyone,

I am planning to learn Java.

Can I access HW registers in Java? Or can I call C function from Java
program?

Thanks.

Even though I don't know much about Java, I know these tidbits:

No, you cannot directly access hardware from Java. I would be surprised
to find a serious Java for embedded use that did not include library
functions to do so, however.

Java itself doesn't provide a means to call C functions, but most Java run
time environments provide a means to call external code. Of course, if
you're calling external code then you have to maintain code bases in C
_and_ Java...

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

 

[dick]

Even though I don't know much about Java, I know these tidbits:

No, you cannot directly access hardware from Java. I would be surprised
to find a serious Java for embedded use that did not include library
functions to do so, however.

Java itself doesn't provide a means to call C functions, but most Java run
time environments provide a means to call external code. Of course, if
you're calling external code then you have to maintain code bases in C
_and_ Java...

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

If I design a HW platform, how can I run Java in this bare machine.

 

[Keith Thompson]

If I design a HW platform, how can I run Java in this bare machine.

Your first step should be to find a newsgroup with "java" in its name.

 

[Sheth Raxit]

If I design a HW platform, how can I run Java in this bare machine.- Hide quoted text -

As per my basic understanding, for your hardware platform you need to
Develop or Port Java Run Time Environment <JVM , regret i am not java
guru and This is not Java-news group, regret if you think replying to
OT>

-Raxit

 

[Tim Wescott]

If I design a HW platform, how can I run Java in this bare machine.

You need a Java run-time environment to run Java, at which point the
machine would no longer (by my definition) be "bare".

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

 

[Ivar Rosquist]

Hi everyone,

I am planning to learn Java.

So you can compile programs once in one platform, and run them
nowhere?

Can I access HW registers in Java?

I bet you can't.

Or can I call C function from Java program?

Yes - using JNI. The catch is that the overhead introduce by this
is such that in most cases the resulting code is almost as slow as an all
Java code.

 

[Chris Dollin]

So you can compile programs once in one platform, and run them
nowhere?

Don't be (a) silly (b) atopical.

I bet you can't.

You can't in C, either.

Yes - using JNI. The catch is that the overhead introduce by this
is such that in most cases the resulting code is almost as slow as an all
Java code.

That is, of course, going to depend on how much work the C code does;
"most cases" is sheer handwaving.

 

[Clever Monkey]

If I design a HW platform, how can I run Java in this bare machine.

[Please don't quote signature blocks. I've correct this here.]

This is, of course, getting way off-topic for comp.lang.c. I'm sure
there is an "embedded Java" newsgroup out there, and Google returns a
sick amount of hits for that phrase.

However, it may be instructive to consider that implementing embedded
systems does not have to be all bare-metal bit-banging. There is a
relatively long tradition of interpreted byte-code slinging in the
embedded world.

It really depends on your application and deployment.

 

[Vladimir Vassilevsky]

Hi everyone,

I am planning to learn Java.

Can I access HW registers in Java? Or can I call C function from Java
program?

Thanks.

http://www.microsoft.com/mspress/books/10457.aspx


Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com

 

[Army1987]

http://www.microsoft.com/mspress/books/10457.aspx

It appears to have nothing to do with C <ot>nor with Java</ot>.

 

[user923005]

Hi everyone,

I am planning to learn Java.

http://www.cafeaulait.org/javafaq.html
followed by

Can I access HW registers in Java?
No.

Or can I call C function from Java
program?

Do a web search for "JNI java". It's a bloody pain in the posterior.
As far as I can see, you have no C questions whatsoever in your post.
Probably, Java questions go better in a Java group.

 

[larwe]

http://www.microsoft.com/mspress/books/10457.aspx

What has Microsoft's proprietary closed nonsense got to do with Java?
Or, for that matter, embedded programming?

 

[larwe]

Can I access HW registers in Java? Or can I call C function from Java
program?

Not directly, and yes, respectively.

There is an implementation of a JVM for AVR; I've seen it mentioned
briefly in c.a.e in response to a thread I posted asking something
related.

There is ALSO an implementation of a JVM for the Commodore 64 (a 1MHz
6502-family device, for those who don't know this).

The real question is, do you understand what Java will provide for
you, and what it will cost you (in terms of resources, performance
etc). I had very specific reasons for wanting to use Java in my
project (it was the PC UI side of an embedded system).

 

[Vladimir Vassilevsky]

What has Microsoft's proprietary closed nonsense got to do with Java?
Or, for that matter, embedded programming?

Stupid questions deserve equaly stupid answers.

VLV

 

[rickman]

Stupid questions deserve equaly stupid answers.

VLV

And you are always there to oblige, right? ;^)

Sorry, I couldn't resist...

 

[larwe]

On Aug 15, 10:23 am, Vladimir Vassilevsky

Stupid questions deserve equaly stupid answers.

The question may have been ill-formed but I do not have enough
information to judge that its intent was stupid.