Bit tricky question for ==

[shauank]

Please finish the declaration of variable x in the bold line below so that the next line prints “false”.

public class Reflexive {
public static void main(String[] args) throws Exception {

<typeX> x = <valueX>;

System.out.prin tln(x == x);
}
}

[r035198x]

Please finish the declaration of variable x in the bold line below so that the next line prints “false”.

public class Reflexive {
public static void main(String[] args) throws Exception {

<typeX> x = <valueX>;

System.out.prin tln(x == x);
}
}

<spoiler>
Suppose x is NaN ...
</spoiler>


Edit: Shouldn't the println say
System.out.prin tln(x == <valueX>);

[JosAH]

<spoiler>
Suppose x is NaN ...
</spoiler>


Edit: Shouldn't the println say
System.out.prin tln(x == <valueX>);

Nope, according to the IEEE definition NaN should compare unequal even to itself.
NaN == NaN should result in false.

kind regards,

Jos

[r035198x]

Nope, according to the IEEE definition NaN should compare unequal even to itself.
NaN == NaN should result in false.

kind regards,

Jos

That's why I suggested it for the println to print false but it wont print false with x == x.
As in
[CODE=java]Double x = Double.NaN;
System.out.prin tln(x == x);
System.out.prin tln(x == Double.NaN);
[/CODE]
prints
true
false

[BigDaddyLH]

That's why I suggested it for the println to print false but it wont print false with x == x.
As in
[CODE=java]Double x = Double.NaN;
System.out.prin tln(x == x);
System.out.prin tln(x == Double.NaN);
[/CODE]
prints
true
false

Very cheeky. Try:
[CODE=java]double x = Double.NaN;
System.out.prin tln(x == x);
System.out.prin tln(x == Double.NaN);
[/CODE]
prints:
false
false

[BigDaddyLH]

Edit: Shouldn't the println say
System.out.prin tln(x == <valueX>);

If you're going to do that, you could also play games with Integer pooling:

Integer x = Integer.valueOf(0);
System.out.println(x == x);
System.out.println(x == Integer.valueOf(0));

Integer y = Integer.valueOf(5000);
System.out.println(y == y);
System.out.println(y == Integer.valueOf(5000));

This prints:
true
true
true
false

[JosAH]

Bugger, that autoboxing thingie again ... where's the guy/gal who invented it? The
window on the attic is wide open; please climb those fine stairs now and wave towards
the general direction of the hungry peasants.

kind regards,

Jos

[r035198x]

... where's the guy/gal who invented it? T...
kind regards,

Jos

Probably enjoying their holiday in the Bahamas with the money he got for inventing it.

[JosAH]

Probably enjoying their holiday in the Bahamas with the money he got for inventing it.

Do you remember this thread?

kind regards,

Jos

[r035198x]

Do you remember this thread?

kind regards,

Jos

It came to my mind when I saw this thread.

[denismox]

shauank, I gave you this test for *you* to solve by yourself and did not ask for a public help, didn't I?

ALL: shauank is an applicant for a job ad and he received a Java Quiz test. Just another cheater, I guess.

Please finish the declaration of variable x in the bold line below so that the next line prints “false”.

public class Reflexive {
public static void main(String[] args) throws Exception {

<typeX> x = <valueX>;

System.out.prin tln(x == x);
}
}

[BigDaddyLH]

shauank, I gave you this test for *you* to solve by yourself and did not ask for a public help, didn't I?

ALL: shauank is an applicant for a job ad and he received a Java Quiz test. Just another cheater, I guess.

Didn't I see this fellow posting several of these interview questions on Sun's Java forums in order to elicit solutions?