How do I read and write system properties using Java?

1. How do I read and write system properties using Java?

   Read:
   

Properties props = System. getProperties ();

Enumeration prop_names = Props.propertynames ();

while (Prop_names.hasmoreelements ()) {

String prop_name = (string) prop_names.nextelement ();

String property = Props.getproperty (Prop_name);

System. out. println ("property" + Prop_name + "are" + Property + "'");

}

write:

system.setproperties (props);

1. Briefly describe the structure and basic usage of the properties file

   Structure: A file with the properties extension, the content is a mapping of key, value, for example "A=2″

Usage:

Public class Test {

Public static void main (String args[]) {

Try {

String name = "Test.properties";

InputStream in = new bufferedinputstream (new FileInputStream (name));

Properties P = new properties ();

P.load (in);

System. out. println ("A's value = =" + P.getproperty ("a"));

} Catch (Exception err) {

Err.printstacktrace ();

}

}

}

How do I read and write system properties using Java?