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How to access environment variable from java class

Posted on 2002-04-10
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Last Modified: 2010-03-31

Hi pals,

I have an serious problem. My java program has to get
environment variables from the system. But how,
I tried lots of methods, but ended in vain.

I'm not expecting suggestions, as i tried a lot but i need a perfect solution.

And guys I thank u al in advance.


Regards,
K.J.S.
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Question by:saurav17
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12 Comments
 
LVL 92

Expert Comment

by:objects
ID: 6933064
Perfect solution: there is none :-(
The only way to access environment vars is by using platform dependent solution using JNI or exec().
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Expert Comment

by:msterjev
ID: 6933085
If you are running on Windows I can give you windows solution!
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LVL 92

Expert Comment

by:objects
ID: 6933098
exec("cmd /c set");
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Expert Comment

by:msterjev
ID: 6933269
I mean more sofisticated solution,something like this:

String path=System.Utils.getEnvironmentVariable("PATH");

or,

Enumeration e=System.Utils.getEnvironmentVariables();

saurav17 can decide which one he want to use!
On the other side, last weak I wrote several such solutions for nothing.Not thanks,saurav17 you can use Runtime.getRuntime().exec("cmd /c set")!
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LVL 92

Expert Comment

by:objects
ID: 6933284
Could certainly wrap the exec call in a method to make it more 'sophisticated' :-)

> solutions for nothing.Not thanks

Get used to it, it happens all the time these days.
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LVL 92

Accepted Solution

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objects earned 100 total points
ID: 6933286
Another option would be to pass the environment variable value when you startup the JVM:

java -Dmyenv=$MYENV myclass
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LVL 9

Expert Comment

by:Venci75
ID: 6933306
As objects said - ther is no perfect solution to this problem. This works on windows and unix, but may be there are systems on which this won't work:
public String getEnvVar(String property) throws IOException {
  String command;
  String os = System.getProperty("os.name");
  if (os.startsWith("Windows")) {
      command = "cmd.exe /C SET " + property;
  } else { // assume that the OS is unix
      command = "echo $" + property;
  }
  Process p = Runtime.getRuntime().exec(command);
  BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
  String line = reader.readLine();
  return line.substring(line.indexOf('=')+1);
}



What kind of environment variables do you need. Some of the values of these variables could be accessed by calling System.getProperty();
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LVL 16

Expert Comment

by:heyhey_
ID: 6933360
you can write a simple .bat file / .sh script that passes these variables to your Java program on startup.


> Get used to it, it happens all the time these days.

hehe
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Expert Comment

by:objects
ID: 6933368
> passes these variables to your Java program on startup.

Already mentioned that :-)
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Expert Comment

by:heyhey_
ID: 6933372
sorry, I missed it :)
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Expert Comment

by:Venci75
ID: 7940543
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:
Answered by: objects
Please leave any comments here within the next seven days.
 
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
 
Venci75
EE Cleanup Volunteer
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Expert Comment

by:modulo
ID: 7990735
Finalized as proposed

modulo

Community Support Moderator
Experts Exchange
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