Logical operator question OCA study guide

[Yik Siew Ngan]

Hi Folks,
   I really appreciate some help on this study guide review question.

What is the output of the following code snippet?

3: boolean x = true, z = true;
4: int y = 20;
5: x = (y != 10) ^ (z=false);
6: System.out.println(x+", "+y+", "+z);

      I could't quite the idea on how Java evaluate the statement on line 5.  How can (z=false) resulted a boolean to be used in the expression?

[Piet Souris]

The expression

z = false

has type boolean and value false. Read more about expressions here: expressions
And so we have in line 5 the exclusieve OR, where the first operand (y != 10) is true, and the second operand (z = false) is false, and so the result is true.

Beware of a possible error here. If the expression was meant to be:

(z == false) // asking whether z is false, but it does not change z

but accidently you write

(z = false)

then you are changing the value of z without getting any warning. Therefore it is wise to always write:

if (z) ...

instead of

if (z == true)

avoiding the possible error of writing

if (z = true) ...