Class blocks won't compile

[Rob Brew]

Copied from the head first Java book, no idea why this won't compile:

StaticTests.java

 class StaticSuper {

	static {
		System.out.println("Super Static Block");
	}

	StaticSuper{
		System.out.println( "super Constructor");
	}
}

public class StaticTests extends StaticSuper {
	static int rand;

	static {
		rand = (int) (Math.random() * 6);
		System.out.println("static block " + rnd);
	}

	StaticTests() {
		System.out.println("constructor");
	}

	public static void main (String args[]) {
	System.out.println("in main");
	StaticTests st = new StaticTests();
	}
}

probably something really obvious, any ideas folks?

Thanks,
Rob.

[Matthew Brown]

Generally speaking, it would help if you told us exactly what error you were getting. That gives us a clue where to look, and what to look for.

In this case, though - take a look at line 7. You're missing some brackets on the constructor.

[Rob Brew]

There was a typing error in the book, brackets in line 7 fixed that.

What i can't understand is why the static field in StaticSuper runs first. What is calling it?

[Rob Brew]

Am i right in thinking the class calls it when main is run?

[Matthew Brown]

Static initialization blocks - which is what you have beginning at lines 3 and 15 - are run when the class is loaded. So that's usually at the first point a reference is made to it. In this case, it will run before the main method does. The StaticTests class has to be loaded before any of its methods can be run, and that causes all its superclasses to be loaded as well.