who can xplain these???

[O Joseph]

Question 13

class A {
  static boolean b;
  public static void main(String[] args) {
    if (b) {
      System.out.print("A");
    } else if (b = false) {
      System.out.print("B");
    } else if (b) {
      System.out.print("C");
    } else if (!b) {
      System.out.print("D");
    } else {
      System.out.print("E");
    }
  }
}

What is the result of attempting to compile and run the above program?
a. Prints: A
b. Prints: B
c. Prints: C
d. Prints: D
e. Prints: E
f. Runtime Exception
g. Compiler Error
h. None of the Above

answer says D, i've tried my best but i still dont understand the logic behind it and similar questions.
secondly: if a variable is declared within an inner class as private. is it visible outside the class? please Explain.
[ edited to preserve formatting using the [code] and [/code] UBB tags -ds ]
[ September 10, 2003: Message edited by: Dirk Schreckmann ]

[Uma Balu]

Hi,

 
class A {
static boolean b;
public static void main(String[] args) {
if (b) { //1
System.out.print("A");
} else if (b = false) { //2
System.out.print("B");
} else if (b) { //3
System.out.print("C");
} else if (!b) { //4
System.out.print("D");
} else { //5
System.out.print("E");
}
}
}
 

Let me try explaining.
A static boolean variable declared and not initialized will get a default value "false".
At 1, the condition is checked for if(b), in sense check if( b==true),
at 2, it is if(b=false), that is value false will be assigned to the boolean variable b and then evaluated as if(b), which is similar to the condition at 1.
Condition at 3 is also similar, all these conditions will be satisfied only if b is true.
At 4, since the condition is if(!b), the expression evaluates to true.
that is,
!b --> true , since b is false.
Hence, D is printed.
Hope this helps,
Uma...

[Praveen Kumar Mathaley]

when if (b=false) statement is executed b is assigned false( note here = operator does not compare the value in java!) in jave to compare the equality operator is ==
The outer class instance can access the private instance variables of its inner class

[Nishu Batra]

Uma is right about the answer.
Two things
default value of b is false.
(b = false ) would assign the value false to b and do a comparison if b is true or not. But since b was false it went to the next comparison.
now when (!b) is dealt with this condition is true and hence we get the output to be 'D'.
--nb--

[O Joseph]

thanks y'll,
please tell me if i'm right to approach it this way:
0 stands for false while 1 for true.
and since 0 and 0 ==0
1 and 0 =1;
b=0;
and any other combination with b that is 0 = false.
so we need !0 to give us true.
which is why D is the correct answer.