compilation error on boolean expression

Question

This is a snippet of Java code:

static boolean a; // gets false
static boolean b; 
static boolean c;

    public void printA(){

         boolean bool = (a = tru         


        

Answer 1

There's no compilation error for me - this works fine:

public class Test {
    static boolean a;
    static boolean b;
    static boolean c;

    public static void main(String[] args) {
        boolean bool = (a = true) || (b = true) && (c = true);
        System.out.print(a + ", " + b + ", " + c);
    }
}

It prints out

true, false, false

This is because the LHS of the || is evaluated, setting a to true and evaluating to true. As the || is short-circuiting, the RHS of || (which is (b = true) && (c = true)) isn't evaluated.

Note that the expression

(a = true) || (b = true) && (c = true);

is equivalent to:

(a = true) ||  ((b = true) && (c = true))

not

((a = true) || (b = true)) && (c = true)

If the latter were the case, you'd get true, false, true.

This is because && has higher precedence ("binds tighter than") ||. See the Java tutorial for a complete list of operator precedence.