Can't understand the Output

[Dean Jones]

public class TestInterface implements InterfaceA, InterfaceB, InterfaceC{

public static void main(String[] args) {

System.out.println(B+C+A);

}
}
 
interface InterfaceA {
public static final int A = 2 * InterfaceB.B;
}
 
interface InterfaceB {
public static final int B = InterfaceC.C + 1;
}
 
interface InterfaceC {
public static final int C = InterfaceA.A + 1;
}

Can some one please explain why the output changes when we change the order of A+B+C to B+C+A or any other combination

[Sunny Jain]

this problem is actually how constant are initialize and how super interface are called in JAVA, let me try to explain you :

Suppose you write :

System.out.println(B);
now see how things work:

interfaceB(B = 0 ) ----> interfaceC( C = 0) -----> interfaceA( A = 2*B)
                                                               |
( B = C +1 = > 2)<---- ( C = A + 1 =>c =1)<----(A = 2 * 0 )<----

in case when B is called first values are :
B =2, C =1, A =0

Similarly When
System.out.println(A);

interfacea(A = 0 ) ----> interfaceB(B = 0) -----> interfaceC( C = A + 1)
                                                                   |
( A = 2 * B = > 4)<---- ( B = C + 1 =>B =2)<----(C = 0 + 1 )<--------

so A =4,B = 2, C = 1

similarly when C is called first :
C =3,A = 2, B =1

so when you call B+C+A
you get : 2 + 1 + 0 = 3

similarly
A + B + C = 4 + 2 + 1 = 7

[Dean Jones]

Thanks a lot Sunny.