Void class?

[santhosh.R gowda]

hi friends

Please giude me the concept of void class in java.lang package..... with example

[Christophe Verré]

It's used to express the "void" keyword. I use it with the java.util.concurrent.Callable interface, to say that I'm not expecting any returned value from the executed thread.

new Callable<Void>() {
	Void call() throws Exception {
		// do something
	}
}

[santhosh.R gowda]

Christophe Verré wrote:It's used to express the "void" keyword. I use it with the java.util.concurrent.Callable interface, to say that I'm not expecting any returned value from the executed thread.

new Callable<Void>() {
	Void call() throws Exception {
		// do something
	}
}

hi friend ...... as you told it is used to express the void keyword... then what is the difference between keyword void and class void...

[Christophe Verré]

In my example, you need a Class to be used as a generic type. "void" is just a keyword, it cannot be used for generic types. You cannot use "new Callable<void>". To correct this, you must use the Void class instead.

[Rob Spoor]

Also, Void.TYPE is what will be returned from Method.getReturnType() for methods that return nothing (void). That's probably where the entire class was originally created for, since generics didn't exist until Java 5.0, but Void exists since Java 1.1.