System programming with java

hi,
i was trying to fetch system related data, like processor usage, through java .. but i couldn't .. i couldn't find any API for the purpose..
finally used some shellscripting...
is there any API for these purpose?
If there are no such APIs then how java.io works?
how it interact with hardware? how it read input from IO devices?

If there are no such APIs then how java.io works?
how it interact with hardware? how it read inputfrom IO devices?
can somebody answer these?Java technology includes an abstraction layer called the Java Virtual Machine. This JVM isolates all system dependencies. Once a JVM exists for a platform, pure Java programs (in bytecode form) will run on that platform.

Similar Messages

OSX 10.4.10, Net beans and Sams Programing with JAVA

I am brand new to Java so I downloaded Net Beans on my MAC. I bought a copy of Teach Your Self Programing with Java in 24 hrs.
So far I got the first three programs to compile on Net Beans but got stuck when they started to talk about arguments. The following will not compile. Starting at line 2
1) System.out.println("The " + arguments [0]
2) + " " + arguments[1] + " fox "
3) + "jumped over the "
4) + arguments[2] + " dog. ")
I get the little red x on each line.
Is the book wrong or am I missing something?
All the tutorials talk about Javac. I can't seem to find it or get to it on my computer. How do I know if I even have it?
And is there such a thing as a "command line" on a MAC?

Hi, you should put any code you post in between code brackets like this:
code here I dont use a mac or netbeans but javac is the java compiler, you would not have been able to compile the first two. The .exe (or whatever mac executable is) is usually located in the lib folder in the java directory. It comes when you download JDK. As for the code, it would help me if you posted the first couple lines of the error message. It looks fine to me, but I would need to see your whole class in order to help you further
and yes there is a command line on a mac...i think its called terminal and usually looks like a little computer
Edited by: jaredL on Sep 20, 2007 7:45 PM
Edited by: jaredL on Sep 20, 2007 7:47 PM

Systems programming in Java

Is it possible to write system programs in java language? where can i find examples?

like writing device drivers or interacting with hardware i.e. ports input/output just like in 'C'..
If it is possible to write device drivers in java.....then we need not to write drivers for Windows, Solaris and linux separately. Just write device driver once and run it anywhere.. i don't know it is feasible or not.
Edited by: arun_maurya on May 7, 2008 2:24 AM

Can i create an exetutable (.exe) program with java???????

I would like to learn how i can create an exetutable (.exe) program with java.
Is there any additional package which i should download or buy it?
Also i would like to write files into CD's direct from my application.
Is there any library which i must download or buy?
Thanks!

check out the free open source GNU gcj native compiler for Java to see if it will do what you want.
http://gcc.gnu.org/java/
for writing data files you could use java.io.BufferedWriter. For sound files, look in the javax.sound package

Never programmed with Java

Hello
I have never programmed with Java, and dont know, what i can do, I use PHP, but, i am only a novice at it.
I was wondering, is it possable to get data from a page, and put it into an image? if there is no data from the page, it will ask for the data to be added, and this will update every so often?
Also, Most of you know about google maps, where you can search for something, well, can i do this same thing in java, have a map, not of the earth, but for a game, and make it easy to add different parts, so that we can search for it, and people can find it easy to look for what they are looking for?

I think Google Maps is programmed in JavaScript using AJAX (short for Asynchronous JavaScript and XML) and is what as known as a web application. Google has released an API (still in beta) for working with Google Maps. The webpage for this API is http://www.google.com/apis/maps/. More about the development facilities Google provides can be found at http://code.google.com/.
I've never read the source code to Google Maps before (a lot of which is available by just viewing the source code of the Google Maps webpage, which can be done by clicking, View > Source in Internet Explorer and View > Page Source in Mozilla Firefox), however I don't think it is a terribly complex application (this does not mean, however, that the source code is easy to read). I think the way it works is by requesting individual images as needed from the Google server and piecing them together on the client side (i.e. in the browser). Basically what you would need to do to use their existing code is to replace all requests made to the Google server with requests to a server of your own and have the server return the corresponding images. This might not be particularly easy to do.
In my opinion, a better approach is just to write your own custom application (probably in Java) which simply mimics the behavior of Google maps, except with your own custom images. This way, you don't have to reverse engineer an entire web application before beginning to write one.
Writing your own application for this purpose is not as difficult as it sounds, especially not in Java. Once understanding the basics, you will not be too far off from being able to write your application.
Let's start with the most basic program (this program would be located in a file called Program.java):
public class Program {
public static void main(String[] args) {
}This program simply starts, does nothing, and exits. I will explain this piece of code line by line, but first, I would like to gauge how much you already know to figure out how best to explain this. Have you used classes in PHP before?

System programming in Java

Hai!!!
Actully I'm working in Automatic distinction between the system progam & application programs. Is there any samples/source code of the system programs available in java???is it possible to distiguish between the system program & Application program by seeing the code??
Cheers!!!

Just curious what is it system programming in java? Can't recall any example...

Embedded system programming in java

I want to know how to do embedded system programming in java.
can anyone give some sample programs and tell me nice book for embedded programming in java

First take a look at Embedded Server forum (http://forum.java.sun.com/forum.jsp?forum=46) and/or OSGi (http://www.osgi.org)

Windows Programming with Java??? Is it possible???

I have a small request from a client (Windows User) who wants a really simple POP3 email checker. I basically need to achieve the same thing that many email clients do, where they show some sort of symbol in the System tray when there is new email. I, however want to do this without the actual email client. All I want is the checker. This program will not download the email, gather information or anything. It will simply check the POP3 account and let the user know if there is new email.
1.Can I get an icon to appear in the system tray and have a program that runs in the background, simply checking the POP3 account for new mail???
2.If it is possible to interact with windows, then how is it done??? If this is too large of a question and you know of some resources that can answer this question for me, that will do.
3.Is it even possible to have Java programs run in the background without appearing in the task bar??
4. Am I trying to do something with Java that it just plain cannot do???

Another really god option is to use the coroutine package from http://www.nevaobject.com/java/index.htm. This allows you invoke COM and Windows API's without having to write the JNI yourself. Its about $695 for a site-wide development license and has no binary distribution costs. A nice, cheap solution to spending lots of hours doing it youself. From the few things I tinkered with, it really does a great job too, but I have not deployed in a real production environment.
Chuck

Is it possible to create java standalone programs with java ME 8

Hi,
Comparing java ME to java SE, I have the impression that midlets are similar to applets.
When working with java SE, I usually make standalone programs.
Now, I wonder if it is also possible to create also standalone programs for java ME, if the classes are only using java ME API's.
I already noticed that netbeans does not allow to build a project that does not contain a midlet, but maybe, it is possible to create a jar file
using the javac and jar commands. Or is there a specific reason why netbeans does not allow to build a project without midlets?
The reason for asking is, that I often make small tools in java that ae then called from a linux script. I imagine that this might be useful on the raspberry pi as well.
Thanks in advance
Jef

Hi Jef -
Comparing java ME to java SE, I have the impression that midlets are similar to applets.
Sort of - similar life cycle methods - so conceptually, yes.
Now, I wonder if it is also possible to create also standalone programs for java ME, if the classes are only using java ME API's.
In a way, yes. If you build an project, you will notice a JAD file and JAR file in the dist directory of the project. JAD is the descriptor for a MIDlet - in mobile devices, the JAD
file is loaded first to determine if the MIDlet has enough privileges to load and run, before the corresponding JAR file is downloaded.
However, the JAD file can also be included in the Manifest of the JAR and the JAR copied to the embedded device manually and run there.
I already noticed that netbeans does not allow to build a project that does not contain a midlet, but maybe, it is possible to create a jar file
using the javac and jar commands. Or is there a specific reason why netbeans does not allow to build a project without midlets?
You can build JAR files and include them into Java ME Embedded projects, but just like Applets, to use the Application Management System (AMS) on the Raspberry Pi, you must have a MIDlet to run.
Perhaps you mean that you would like to launch the AMS and load a MIDlet from the command line on the Pi?
If so, take a look at this section of the Getting Started Guide for the Raspberry Pi.
Tom

System programing using Java

What java class library that i can use for system programing?

Do you mean device drivers and the likes? Java isn't the language for that. You can always interface Java with C and there's also the Micro Edition of Java. It depends on your situation if Java is useful.

System control with java, and networking in jave

Hi, just a couple of questions.
Ill start witht the networking query. Ive been making a basic network chat program using sockets. The text is transfered through the sockets as strings read in from text field on the interface
eg
kkSocket = new Socket("xxx.xxx.xxx.xxx", 80);
out = new PrintWriter(kkSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(kkSocket.getInputStream()));
String fromUser = (ba.text());
out.println(fromUser);
All this works fine, i want to impliment file transfer into the app, but im clueless how to transfer anything other than a basic string over a socket, let alone send it to a specific location on the client computer. Any help / advice would be well recieved.
Also, as i have basic code, that can connect computers, and send messages between them, i was wondering how i control some of the system functions, like executing files, opening / closing cd tray etc through java. As with this, i could create a mini remote control application.
Again, any help on this (or even a pointer to relavent things in the java api) would be fantastic as the more i can understand the more inventive i can be when coding
Cheerz

You seem to manage well even though you're posting to New To Java Technology, I've seen far worse questions in ALT even...
All this works fine, i want to impliment file transfer into the app, but im clueless how to transfer anything other than a basic string over a socket, let alone send it to a specific location on the client computer.To send files/binary data, you would use a BufferedInputStream (remember Streams are for binary data, Readers/Writers are for text) in a similar way you're using PrintWriter and BufferedReader now.
It could go a bit like this (invent your own protocol):
User1 sends a String that says: FILE C:\directory\file
User2 receives the String and prepares to save a file to the specified directory.
User1 sends the binary data to User2.
User2 reads the binary data and writes it in the file.
Controlling system functions in Java can be tricky, so you might not get all the functionality in your program that you want. Running programs can be done through System.exec(), but the CD tray might be impossible even.

How to do a program with java user intarface (internet app) and c++ core

I want to do a program to run on the internet with java
but to run the mathematical core with c++ on a SUN machine.
so, any help will be cool!, any tip about this subjet
will be apreciate!
my mail is [email protected]
and [email protected]
I am doing a Phd on electronics and i want to do
a circuit simuilator online.
thanks!

One option is to use Java Native Interface (JNI).
http://developer.java.sun.com/developer/onlineTraining/Programming/JDCBook/jni.html

Writing Programs with java in 10.3.9

So, I'm trying to teach myself the basics of Java. Here's what I did:
I went to the apple website and poked around until I found what I THOUGHT was the right download. (JavaForMacOSX10.3Update5.pkg). This SEEMS to have created a Java folder (Applications/Utilities/Java) However I can't confirm that it wasn't there before I downloaded and ran the JavaForMacOSX10.3Update5.pkg. Inside this folder are four applications (Applet Launcher, Input Method HotKey and two other PlugIns).
After reading a bunch of stuff about Java it seemed like I needed to be working with the Terminal Application in order to do command line stuff. I wrote a little program in TextEditor, saved it as "HelloApp.java" (like the book told me to) and then went to Terminal to try to compile it.
When I open Terminal, here's what I see:
Last login: Tue Jun 10 19:29:19 on ttyp1
Welcome to Darwin!
[Peter-Booths-Computer:~] peterboo%
I typed in <javac HelloApp.java> and here's what I got back:
error: cannot read: HelloApp.java
1 error
[Peter-Booths-Computer:~] peterboo%
Sooo... my questions:
How do I tell the computer through command line entries exactly WHERE my HelloApp.java file is? On a PC, they do something like cd C:/ to change directories to the location where the file is saved. Is there an equivalent command on a Mac?
I'm not even sure that I've got the Java JDK or JSE or whatever the heck it's called on my computer. Can someone tell me how to figure that out?
Is there a slicker way to compile, run etc. code with Java beside command line stuff in Terminal?
Thanks a TON to anyone who can help me.
Peter Booth
Message was edited by: Peter Booth1

Specify the path in the Terminal; a path will look like ~/Desktop/HelloApp.java if the item is on your desktop; when starting a path, ~ refers to your home folder, while / refers to the top level of the drive. Using 'cd' followed by a path will take you to that location from your current folder unless the path starts with a ~ or /, which work as above.
A path which starts with ../ refers to the folder enclosing the one you're currently looking at.
(32782)

Homgeneous System Copy with Java and DB2 with database tools.

Hello,
we have an single java stack (netweaver 2004s) and tried a system copy with database tools.
Source System: DP2, dp2adm, db2dp2, sapdp2db
Target System: SP2, sp2adm, db2sp2, ???
We followed the documentation "System copy for SAP systems based on sap netweaver 2004s SR1 JAVA. We exported the SDM on the source system made a redirected restore with db tools and tried to install a new target system.
During the import in the target system using sapinst we get in the
phase run java migration tool kit the following error message.
Caused by:
com.sap.engine.frame.core.configuration.ConfigurationException: Error
while connecting to DB.
at
com.sap.engine.core.configuration.bootstrap.ConfigurationManagerBootstrapImpl.(ConfigurationManagerBootstrapImpl.java:49)
... 14 more
Caused by: com.ibm.db2.jcc.a.SqlException: Connection authorization
failure occurred. Reason: userid revoked.
What I didn't understand is, that in the documenation it is mentioned, that you have to use the same java database connect user. But during the installation of the target system (SP2) I cannot change the java database connect user to sapdp2db. I'm only allow to enter sapsp2db. That might then cause the connection problem.
Regards
Alexander Türk
I

Hi Alexander
yes , give it a try , but see note
970518 Hom./Het.System Copy SAP NetWeaver 2004s SR2
and all other related notes , if it matches your environment .
Best regards
dirk

Trying to run programs with java 1.4.2_07 after upgrading Eclipse

Hi All,
I'm using Eclipse version 3.1.0 and java 5.0 (1.5.0_03). I changed the JRE of a program back to 1.4.2_07, but when i try to run it i get this:
Exception in thread "main" java.lang.UnsupportedClassVersionError: controller/Controller (Unsupported major.minor version 49.0)
     at java.lang.ClassLoader.defineClass0(Native Method)
     at java.lang.ClassLoader.defineClass(ClassLoader.java:539)
     at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
     at java.net.URLClassLoader.defineClass(URLClassLoader.java:251)
     at java.net.URLClassLoader.access$100(URLClassLoader.java:55)
     at java.net.URLClassLoader$1.run(URLClassLoader.java:194)
     at java.security.AccessController.doPrivileged(Native Method)
     at java.net.URLClassLoader.findClass(URLClassLoader.java:187)
     at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:274)
     at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
     at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:302)What the %^#@ ? Will appreciate any help.
Regards,
snayit

Also, another thing people may want to try. A coworker was having a problem where she kept getting the unsupported major minor version error from eclipse after upgrading to the latest version of java.
All the configuration settings were correct, pointing to the latest vm. I tried starting eclipse with the parameter
-vm "C:\Program Files\Java\jdk1.5.0_04\jre\bin\javaw.exe"
and it worked just fine. Without this, it was apparently finding some conflict between jdk1.5 and the older jdk1.4.
IDE's are nice, but I find configuring them after an upgrade to be exremely painful.

System programming with java

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