Can someone explain why this happens?

sample quiz question
suppose that the following variable declarations have been made:
int i = 0, int k = 0; String s = "@"; Give the exact output produced by the following code fragments:
(a)
System.out.print(i==3); // I know this won't work
(b)
System.out.println("Ans: "+(j++)+(++j)+(j++)+(++J); // I don't understand why it gives 0224 and not 1234 :confused:
(c)
for (; k<3; k++) {
System.out.print(s);
s = s+s;
}
System.out.println(s); // I need to know why it returns 15 @ signs and not seven :confused:
Thanks for the help :)

Quote:

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System.out.print(i==3); // I know this won't work

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this will work , it will produce boolean value ( equals false . )
this expression means " is ( i == 3 ) true ? "

Quote:

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(j++)+(++j)+(j++)+(++J)

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j++ means do something with j, later increase it.
++j means increase j, later do something with it.

Quote:

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for (; k<3; k++) {
System.out.print(s);
s = s+s;
}

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after 3 steps :
s = @ (1) -->@@ (2)-->@@@@(4) all of them printed..
( now s =@@@@@@@@(8) )
and s printed too.
1+2+4+8 = 15 @