env varriables

[Tirthankar Dutta Chaudhuri]

Hi ,
I need a java code that gives me the env varriaales .
Can any one help .

Thanks
Tirthankar

[Joe Ess]

This is an advanced question?

  
Map m = System.getenv();

[Ernest Friedman-Hill]

No, it's not. Off to JiG Intermediate.

[Mani RMK]

Try this code piece.

import java.util.Enumeration;
public class Env {
public static void main(String[] args) {
Enumeration objEnmSys = System.getProperties().keys();
while (objEnmSys.hasMoreElements()){
String strProp = objEnmSys.nextElement().toString();
System.out.println(strProp+"\t:"+System.getProperties().getProperty(strProp));
}
}
}
[ May 21, 2005: Message edited by: Mani RMK ]

[Sol Mayer-Orn]

Unfortunately System.getenv() is deprecated and doesn't work at all.

The documentation recommends to use System.getProperty() , as states in the previous reply.
However, we need to clarify that these are not the same.... you need to manually translate "environment vars" into "java system properties". This is usually done at the command-line executing java.

Example:

1. On the OS level, set an environment var: 
Windows example: 
> set MyVar=foo
 
2. On the java command line, copy your var into a java property "myProp".
Windows example (assuming you class is called MyMainClass, and assuming MyVar does *not* contain any spaces):
> java.exe -DmyProp=%MyVar%  MyMainClass
 
3. In the code of "MyMainClass.java", lookup this system property:
public static void main(String[] args){
  String v= System.getProperty("myProp");
}

Cumbersome as it might seem, it does a good job separating java from the native platform. This approach is used by various commercial products, including Tomcat.

In rare cases when you feel there's no way you can take this approach, you can alwasy use the *platrom dependent* alternative, using Runtime.exec:

// Windows example. 
// Warning: platform dependent , try to avoid it if u can:
Process p=Runtime.getRuntime().exec("cmd  /C echo %DSQUERY%");
p.waitFor();
BufferedReader br=new BufferedReader(new InputStreamReader(p.getInputStream()));
String val=br.readLine();
br.close();
System.out.println(val);

[Sol Mayer-Orn]

sorry, %DSQUERY% is just a system variable. Replace it with %MyVar%.

[Stefan Wagner]

I use:

Map <String, String> m = System.getenv ();
Set<Map.Entry<String, String>> s = m.entrySet ();
for (Map.Entry me : s)
{
System.out.println (me.getKey () + "=" + me.getValue ());
}

Unfortunately System.getenv() is deprecated and doesn't work at all.

does work for me.
From the javadocs:

When passing information to a Java subprocess, system properties are generally preferred over environment variables.
(...)
Since:
1.5

Introduced in 1.5 and deprecated today?

[Ernest Friedman-Hill]

getenv() was present in early versions of Java; then it was deprecated for a few years; then in Tiger, it was un-deprecated, and now there's a shiny new version that returns the whole environment, as Stefan demonstrates.

Sometimes the Javasoft folks give in to a little pressure.

[Sol Mayer-Orn]

Sorry, wasn't aware of that (my company's still using 1.4).
Thanks.