Strange Assertion Behaviour

[Arthur Blair]

In the following example from Dan Chisolm:

    
public class Assertions {
    
    private static int x1;
    
    public void setX(int x) {x1 = x;}
    
    public int getX() {return x1;}
    
    public static void main(String[] args) {
        int i1 = 0, j1 = 0;
        do {
          System.out.print(j1++);
          assert (i1 = j1 + x1) < 6;
        } while (i1 < 3);
    }    
}

I would have thought that this wouldn't compile because the expression i1 = j1 + x1 doesn't return a boolean, it returns an int. I thought that the assert() method needed to receive a boolean. So what is going on here? I'm a little confused.

[marc weber]

The complete expression is (i1 = j1 + x1) < 6; which does return a boolean.
[ February 10, 2006: Message edited by: marc weber ]

[Joshua Smith]

Arthur-

You're right that (i1 = j1 + x1) doesn't return a boolean, but (i1 = j1 + x1) < 6 does. It's saying "assign i1 the value of j1 plus x1 and then compare the result to see if it's less than 6.

(i1 = j1 + x1) < 6

translates to

result of addition assigned to i1 compared with 6

and that evaluates to a boolean.

Josh

[Arthur Blair]

clearly my brain isn't working today. Thanks guys.