assertions

[Tamara Lopez]

Hello
What is the difference between:
java -da com.blah.MyClass
and
java -da:com.blah.MyClass

Why is the first one considered to be with no arguments? (from K&B p378)
Thanks

[Phil Kurian]

Hi,

Syntax for assertions is:

java (-da|-ea)(:class to enable or disable assertions) [class to run]

(items in the '()' are optional).

The first one:
java -da com.blah.MyClass is the same as running java com.blah.MyClass.

Assertions are disabled by default, so the -da by itself is superfluous.

The second one:

java -da:com.blah.MyClass

would not work at all because you need to tell it which class to run if you use the -da: syntax. All -da:<class_name> does is to disable assertions for <class_name>. You still need to tell it which class to run.

i.e. you would need to do somthing like this.

java -da:com.blah.MyClass com.blah.MyClass

Once this is done all the statements below achieve exactly the same thing, in that they disable assertions in the class com.blah.MyClass

java -da:com.blah.MyClass com.blah.MyClass
java -da com.blah.MyClass
java com.blah.MyClass

Hope that helps

[Changchun Wang]

from web page

no arguments
Enables or disables assertions in all classes except system classes.
packageName...
Enables or disables assertions in the named package and any subpackages.
...
Enables or disables assertions in the unnamed package in the current working directory.
className
Enables or disables assertions in the named class

so java -da com.blah.MyClass <no arguments>

java -da:com.blah.MyClass <disables assertions in com.blah.MyClass class >