Proper usage of Java -D command-line parameters
I suspect the problem is that you've put the "-D" after the -jar
. Try this:
java -Dtest="true" -jar myApplication.jar
From the command line help:
java [-options] -jar jarfile [args...]
In other words, the way you've got it at the moment will treat -Dtest="true"
as one of the arguments to pass to main
instead of as a JVM argument.
(You should probably also drop the quotes, but it may well work anyway - it probably depends on your shell.)
That should be:
java -Dtest="true" -jar myApplication.jar
Then the following will return the value:
System.getProperty("test");
The value could be null
, though, so guard against an exception using a Boolean
:
boolean b = Boolean.parseBoolean( System.getProperty( "test" ) );
Note that the getBoolean
method delegates the system property value, simplifying the code to:
if( Boolean.getBoolean( "test" ) ) {
// ...
}
You're giving parameters to your program instead to Java. Use
java -Dtest="true" -jar myApplication.jar
instead.
Consider using
"true".equalsIgnoreCase(System.getProperty("test"))
to avoid the NPE. But do not use "Yoda conditions" always without thinking, sometimes throwing the NPE is the right behavior and sometimes something like
System.getProperty("test") == null || System.getProperty("test").equalsIgnoreCase("true")
is right (providing default true). A shorter possibility is
!"false".equalsIgnoreCase(System.getProperty("test"))
but not using double negation doesn't make it less hard to misunderstand.