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Interface question

 
Bob Young
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Posts: 65
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Consider the following code:
interface I
{
int i = 1, ii = Test.out("ii", 2);
}
interface J extends I
{
int j = Test.out("j", 3), jj = Test.out("jj", 4);
}
interface K extends J
{
int k = Test.out("k", 5);
}
class Test
{
public static void main(String[] args) { System.out.println(K.j); }
public static int out(String s, int i)
{
System.out.println(s + "=" + i);
return i;
}
}
Prints: j=3 jj=4 3. I don't understand how the jj=4 is also printed. Can anyone enlighten me on this? Thanks.
 
Manfred Leonhardt
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Posts: 1492
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Hi Bob,
IMO it appears because the interface j gets loaded. Since all variables in an interface are assumed static then the initialization happens at load time. Since you have requested to print out K.j the class needs to be loaded. Therefore all initialization will take place. Since your init code prints things out you get both j and jj print outs. Then your print goes ahead and prints out the value for you.
Regards,
Manfred.
 
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